ML14045A394
| ML14045A394 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 12/27/2002 |
| From: | Swan F Pacific Gas & Electric Co |
| To: | Document Control Desk, NRC/FSME |
| Shared Package | |
| ML14045A387 | List:
|
| References | |
| HBL-14-008 TR-HBIP-2002-01 | |
| Download: ML14045A394 (100) | |
Text
Thatcher, Wayne, and Plafker, George, 1977, The Yakutat Bay, Alaska, earthquakes [abs.]:
Seismograms and crustal deformation: Geological Society of America Abstracts with Programs, v. 9, no. 4, p. 515.
Tobin, D., and Sykes, L., 1968, Seismicity and tectonics of the northeast Pacific Ocean:
Journal of Geophysical Research, v. 73, p. 3821-3845.
von Huene, R., Shor, G.G., and Malloy, R.J., 1972, Offshore tectonic features in the affected region in The Great Alaskan Earthquake of 1964, Oceanography and Coastal Engineering, Wash., D.C., Nat. Res. Council, National Academy of Science, p. 266-289.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 2A-10 Appendix2A Rev. 0, August 23, 2002
CiQ o--.._
\\l..
~
68°
\\ c c
(~
166 0
I 0
I 200 200 I
I
~~oo
.... **;t;.::
I 00 tv rles I
600 Kilor eters Figure 2A-1 Tectonic setting of the 1964 Alaska earthquake showing the eastern Aleutian volcanic arc and trench, the earthquake epicenter, and the areal distribution of associated zones of vertical land-level change. The Aleutian arc is an ensimatic island arc west of the end of the Alaska Peninsula, and a continental margin arc to the east. (Plafker, 1969).
.. Humboldt Bay ISFSI Project r!lf&~ Technical Report I & TR-HBIP-2002-01 2A-ll Appendix 2A Rev. 0, August 23, 2002
NORTH AMERICAN PLATE Figure 2A-2 Proposed simplified model for present crustal deformation along Pacific-North American plate boundary in southern and southeastern Alaska. Circled numbers give rate of motion (cm/yr) of Pacific plate, Yakutat block, (YB), St. Elias block (SE), and Wrangell block (WB) relative to North American plate. Numbers next to paired vectors give rate of motion across indicated zone. Dotted bands enclose surface outcrops of major zones of deformation and faulting along the NW and SW margins of the Wrangell block. (Lahr and Plafker, 1980).
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 2A-12 Appendix 2A Rev. 0, August 23, 2002
S:\\51 OOs\\5117\\5117.009\\task_13\\02_1230_s2a\\_fig_02a-03{03).ai Figure 2A-3 Major structural features along the Gulf of Alaska margin and the northeastern end of the 1964 Alaska earthquake rupture zone (yellow) and known or suspected active faults (red). Fault abbreviations are: AM-Aleutian megathrust; TFS-Transition fault zone; FF-Fairweather fault; KIZ-Kayak Island zone; PZ-Pamplona zone; DRZ-Dangerous River zone; PBF-Patton Bay fault; RMF-Ragged Mountain fault; WF-Wingham fault; RMF-Ragged Mountain fault; CSFS-Chugach-St. Elias fault system; CFS-Contact fault system; CMF-Castle Mountain fault; TF-Totschunda fault; DFS-Denali fault system (Plafker and others, 1994).
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Appendix 2A Rev. 0, August 23, 2002
S:\\5100s\\5117\\5117.009\\task_13\\02_1230_s2a\\_fig_02a-04(04).ai 0
I 63 mm/ yr 0
56 mm/ yr l!I!!J..._ 1 9 8 8 500 K I L 0 M ETERS I
I 300 M ILES EARTHQUAKE MAGNIITUDE
<7_0 7.0 - 7.9 8.0 -8.4 e 8.s - s.9 9.0 or larger Earthquake rupture zone 1964 and date of most recent rupture Sl mrn/ yr M a~ itu d e 8. 1 8/ 22/ 1949 Figure 2A-4 Inferred rupture zones of major plate-boundary earthquakes along the northern Gulf of Alaska margin and location of the "Yakataga seismic gap" (white). Modified from Plafker and others {1994).
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Appendix 2A Rev. 0, August 23, 2002
sa*
- 15ft EXPLANATION
--s--............,...
Isobase contour, showing uplift
( +) or stibsidence ( - )in feet D<lshed where a *pp *ro~imat e ty lo-cated; dotted *when l:.,~fer re d
____ _L __
Approximate axis of maximum uplift
+--
Apprmdmate axis of maximum subsidence
\\ \\ \\\\\\\\\\\\\\\\\\\\\\ \\\\\\
Pos.'lihle zone of sligl\\t uplift (less than 2 ft)
U.S. Coast. and Geodetic Survey first order level net.
Active or dormant volcano 152° 150° 0
148°
./"
/
0 50 100 14 2° 150 r*11LES 150 KILOM ETERS SUB ~1Afl 1N E CONTOURS IN FEET Figure 2A-5 Tectonic uplift and subsidence and surface faults at Montague Island associated with the March 27, 1964 Alaska earthquake. Land level change, in meters, is shown by the contours, which are dashed where approximate or inferred. The outer edge of the continental shelf, at -200 m, is shown by the dotted line. Active or dormant arc volcanoes are shown by stars. The profile shows vertical displacements.along line A-A' (dotted where inferred). From Plafker (1965).
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 2A-15 Appendix 2A Rev. 0, August 23, 2002
- ~
(0 0 (0 0
cO N
0 I
Ol
~I N
~I (V)
N
.-I N
.9 (V) :I
(/")
§;
0 0,...;
~
(/")
0 0
~
Vi
,--_:_'r
.,;../:....
' -----~ii;.:;
' '-' -----~=-,..- -~--,---i-r-------;r-----;~ ' '--.----
({
~
/
I I
I I
I I
I I
I I
l_
fTE- / t.I[ Tf RS
. 4'
- Trh1 l ty I Sil' nds *- __.* /*
I
\\
I r,
It
~
/ --
A ll'll tian Trench
- v
~
,.1
~ ~~ - -?
I 2
____,., /
-::J.
10 ProliiP. ;, lo ng line A-.-1',;how1ng 1nferred 10 1t1al wave form-caused by tectontc displacements or the sea lloor
~-----------~--------~-----
EXPLANA T ION Wave travel direction inferred from shoreline damage or eyewitness accounts Calculat.f>d maximum distance trav-elled by iniLial wave
- --+----
Axis of su b~idence
0-------
Zero isobnse contour Dashed whert approximate Epicenter of majol' aftershock ( M ~ 6.0)
Axis of uplift Dashi!d wll~r~ injrrr~d (j)
Station listed in table 2 Figure 2A-6 Submarine extension of the zone of maximum uplift and faulting on Montague Island as inferred from movement directions and calculated travel distances of seismic sea waves generated by the tectonic displacements (Plafker, 1969).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Appendix 2A Rev. 0, August 23, 2002 2A-16
Vi 0
0 A.
12
- E -
8 z
ww u~
<XLU 4
U..<..)
ll::<:(
- >_j 0
C/)o_
en
-2 0
50
~
- X:
PACIFIC PLATE
- X:
1-100 a..
I 150 200 100 0
100 200 DISTANCE PERPENDICULAR TO ZERO ISOBASE (KM)
~ -
8 t-z Ww 4
(..)~
<tw LL.(..)
O::<t 0
- >......1 en~
Edge of
-2 (f)
Axis of a
Peru - Chile E
w Tre nch 0
50
- X:.
I 1-foo Q_
w 0
150 B.
100 o*
100 2.00 DISTANCE PERPENDICULAR TO 7ERO IS 0 BASE ( K M)
Figure 2A-7 Schematic cross sections showing the suggested mechanisms for (a) the 1964 Alaskan earthquake and (B) the 1960 Chilean earthquake. Inferred earthquake faults are shown by solid lines; possible faults by dashed lines; arrows indicate sense of movement. Dotted lines, possible fault boundaries that did not slip.
Profile of vertical displacement above section (A) is the same as in Figure 5 except that it is reversed to have the ocean basin to the left. After Plafker (1972).
Lt.J 0
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Appendix 2A Rev. 0, August 23, 2002 2A-17
- £::~
~ [,
UJ -1 2
'I
~7 -t f[l
.~. t; ro
- ~
J - - -*-------
1J,)II1!.1n
,\\* od 1JI~ fc10 Pn ' l::m f~O *
'; olconi-;
fre rt ~ I I ~IOnd F'a,Jff
.~, -~
~
0
'. + -.:-.:; ___ ~- ~
- ~~ --. _ _ _ N_O_ R_ *_rH_ A_f\\*1_E_R_IC_A_N '-1:.
2 I SEi-"mugcr**--* '", 1-PLATE
~
~
- r. ertnr.e.
~so-PACIFIC PLATE ANID MANTLE - - ---.,------ --..,--------r-- ---..... "_- -. _
HN= 1 1-:o--
100
.:. ] _
___ _ DAi,~rm.<<tion Cltl ngc ir.
Fr*:*t F*>I:J 7~cn ~~
1::
If.
630 -
swl-&
[,20
~
sz 40 _i~
GORDA PLATE AND MANTLE
~0 0
20 Urtle Salrnon P.tull ZonB '*,,
- \\
f.ll ad River Fa ut Zom~
300 400 NORTH AMERICAN PLATE NE Figure 2A-8 Profile and section of coseismic deformation associated with the 1964 Alaska earthquake (location on Figure 2A-5) and a hypothetical great megathrust earthquake across the southern Cascadia margin (north of Humboldt Bay). (A) Profile of horizontal and vertical components of coseismic slip across the region affected by the 1964 Alaska earthquake (above) and inferred slip partitioning between the megathrust and intraplate faults, assuming average intraplate surface fault dip of 40?-60? (below). (B) Hypothetical profile showing possible vertical component a the Little Salmon fault zone (LSF) and Mad River Fault zone (MRZ) assuming minimum megathrust slip of 12m and average intraplate surface fault dips of 40?. Two possibilities are shown for vertical displacement assuming either that all 12 m of mega thrust slip is transferred to the LSF (7. 7 m) or that slip is partitioned between the LSF (6 m) and MRFZ (2 m). Alaska data after Plafker, 1967) and Plafker and others (2000) ; Cascadia data from Carver and others, {1999).
2A-18 m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Appendix 2A Rev. 0, August 23, 2002
Appendix 4A Logs of Earth Sciences Associates (1977) and Woodward-Clyde Consultants (1980)
Site Trenches Revision 0-September 16,2002
Appendix 4A Logs of ESA and wee Site Trenches LIST OF FIGURES Figure 4A-I Geologic log of Trench BP-I (From Earth Sciences Associates, 1977, figures C2 through C34).
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 1I Sheet 12 Sheet 13 Sheet 14 Sheet I5 Sheet I6 Sheet I7 Sheet 18 Explanation of data shown on trench logs Trench BP-I, Station 0+00 to I+ I 0 Trench BP-I, Station 1+IO to 2+20 Trench BP-I, Station 2+20 to 3+30 Trench BP-I, Station 3+30 to 4+40 Trench BP-I, Station 4+40 to 5+50 Trench BP-1, Station 5+50 to 6+60 Trench BP-I, Station 6+60 to 7+70 Trench BP-I, Station 7+70 to 8+80 Trench BP-I, Station 8+80 to 9+90 Trench BP-1, Station 9+90 to 1I +00 Trench BP-I, Station II +00 to I2+ IO Trench BP-1, Station 12+10 to I3+20 Trench BP-I, Station 13+20 to I3+75 Trench BP-1, Station 13+75 to 14+41 Trench BP-1, Station 14+41 to 15+25 Trench BP-1, Station 15+25 to 16+ I 0 Trench BP-I, Station I6+ I 0 to 16+45 Figure 4A-2 Geologic log of northeastern part of trench BP-2 (Modified from Earth Sciences Associates, 1977, Figure C37)
Figure 4A-3 Geologic log of trench BP-3 (Modified from Earth Sciences Associates, 1977, Figure C38)
Figure 4A-4 Geologic log of trench BP-4 (From Earth Sciences Associates, 1977, Figure C35)
Figure 4A-5 Geologic log of trench BP-5 (From Earth Sciences Associates, 1977, Figure C40)
Figure 4A-6 Geologic log of trench BP-6A (From Earth Sciences Associates, 1977, Figure C41)
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 4A-i Appendix4A Logs ofESA and wee Site Trenches Rev. 0, September 16, 2002
APPENDIX4A LIST OF FIGURES (Continued)
Figure 4A-7 Geologic log of trench BP-6B (From Earth Sciences Associates, 1977, Figure C42)
Figure 4A-8 Geologic log of trench BP-7 (From Earth Sciences Associates, 1977, Figure C43)
Figure 4A-9 Geologic log of trench BP-8 (From Earth Sciences Associates, 1977, Figure C44)
Figure 4A-10 Geologic log of trench BP-9 (From Earth Sciences Associates, 1977, Figure C45)
Note:
A geologic log of trench BP-10 is not included in Annex B because "Field inspections of this trench revealed no offsets, but caving and partial flooding by rain water prevented making a detailed geologic log." (Earth Sciences Associates, 1977, Appendix C).
Figure 4A -11 Composite stratigraphic section and lithologic descriptions of trenches 11-T6a, 11-T6b and 11-T6c (Modi.fied.from Woodward-Clyde Consultants, 1980, Appendix C).
Figure 4A-12 Log of Trench 11-T6a (From Woodward-Clyde Consultants, 1980, Figure C-29).
Sheet 1 Trench 11-T6a, Station 0 to 50 Sheet 2 Trench 11-T6a, Station 50 to 103 Sheet 3 Trench 11-T6a, Station 103 to 178 Sheet 4 Trench 11-T6a, Station 178 to 228 Figure 4A-13 Detail of stratigraphy in trench 11-T6a at station 75.5 meters (From Woodward-Clyde Consultants, 1980, Figure C-30a).
Figure 4A-14 Detail of stratigraphy in trench 11-T6a at station 128 meters (From Woodward-Clyde Consultants, 1980, Figure C-30b ).
Figure 4A-15 Detail of stratigraphy in trench 11-T6a at station 200 meters (From Woodward-Clyde Consultants, 1980, Figure C-30c).
Figure 4A-16 Log of trench 11-T6b (Modified from Woodward-Clyde Consultants, 1980, Figure C-33).
Figure 4A-17 Log of trench 11-T6c (Modified from Woodward-Clyde Consultants, 1980, Figure C-35).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 4A-ii Appendix4A Logs ofESA and wee Site Trenches Rev. 0, September 16,2002
Ill
~------~~~~--~------------------------------
a:r*AAlfl' Ez/Ea 1/IUCArtiJI llftrtllff I.IIAAtJt1 rtUICAL
- -...,.!{_,~~~!,~~.'.~*********
(lfOifiZ.,W ClfACifl)
~---------------4----------------------------------P--
UOIStfl.,lfC-~-..........lhl\\~
ll.lfl UMIIIA,flfl
- .*:...* ~*.:.*
-~,,..
~
SlfYE'I STAT/11111/16 AtiiNG TUIICif I
9 +911 I
l
Cz 6lOIIIfl su*rAcE
.A liMIT COIITACT 8
- Til' II TllNC/1 MAIICU 1 CIIITACT c
SUIIIIIT CIIITACT D
E
~
TUNCR UTTIIM X
fUN OliiJ ctUST; 1/AU "MAJICU' UIIIT Ill TlEICII WATt.t UIIEt.
IN£ tiTIIICIGr (6,) &IAIES Til AIIOTIIEI (46) AIIUT Ill TilE A*EA IIF Tit£ trMIIJt.
UIIMA/1,4lE GI.AilATIIIII UTWEEII TWO tiTIIOt061S.
I.
MATUIILS 1M TI.ENCII AU IUIITIFIEIJ 41' UNIT (UTTEI.) Alii (ITNIJtiGP (IIUM4EI.
SUISCIIPT) Alii AlE lEVEl TO TA5U 1, AIIIJ fJESCtiiEIJ IN IETAIL IN TA4tE 2.
Explanation of data shown on Earth Sciences Associates (1977) trench logs (From Earth Sciences Associates, 1977, Figures C2).
Figure 4A Sheet 1 of 18 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
I,.,
I I
I
- +U I
I 1+..
I I 't.,
I o+H I
I 'i,.
I I
o+l*
I
---~*~+:a~----------~-----=~~~~~~~::~~fO!
I
'i"'
I See Figure 4-2 for location of trench.
*~t~*~-----------=*_:_
1
---~~~~-=-;~~:~a 1
1977 figures C4 and CS).
+00 to 1 + 10 (From Earth Sciences AssocJates.
Log of trench BP-1, Statwn 0 d f om the eastern end of trench.
Station numbers are in feet measure r
611/UIIC lH "
T#EIC/t u-1 JT.tTfll,.IS Tl l*ll
,IUAI Cl I
O+H I
Figure 4A-l-Sheet 2 of 18 Humboldt Bay TSFSI Project Technical Report
~
TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
~---~----------------------.:::=::--.-----------...
I.......
I I
I+IJ I
I
. 'i" I
't" I 1+,.
I
'~~
11111~/C II~,
T#EICA' N*l JTATIIN 1*11 71 1*11 1'16111# Cl
- -~-----------
I t+IJ I
I '+"
I I
I+~
I
__................ ---------------------------------------------------.. _____ !!f~-----
- -..'.:*********-:**.:::::::..-***---***-*******--******-;r******--**---------**--******--**************
I....
I
~~~====z:zzzi!.~~~~-~-111/M* IWN H
M.tlln C!lfTAtr liliH.TWIIfr/llfAUIIM
~.,.,,
J.#T.AIITI/1 llt.rfi IMM#CliNT JI&T I
I+U I
I l+t*
I Log of trench BP-1, Station 1 + 10 to 2+20 (From Earth Sciences Associates, 1977, figures C6 and C7). See Figure 4-2 for location of trench.
Station numbers are in feet measured from the eastern end of trench.
Figure 4A-l-Sheet 3 of 18 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
I 1+4#
I I
1+11 I
I H..
I I
1+41 I
I
- +..
I
&Ediii/C td& IF TAE/fCN U*l JTArl#~ r~N r* ~*fl 1'1.11#1 Cl I
I+H I
I
- +~*
I UllHit lll N TIIK~N U.l JT.tT/1111 r*1S Tl ~*H
"~""' c, I.....
I I *r-I
- +..
I I *+*
I I
1+10 I
I 6+**
I I
~+,
I I,.,.
I I,...
I Log of trench BP-1, Station 2+20 to 3+30 {From Earth Sciences Associates. 1977. figures CB and C9). See Figure 4-2 for location of trench.
Station numbers are in feet measured from the eastern end of trench.
I I+H I
I...,.
I Figure 4A-l -Sheet 4 of 18 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
6llli61C 116 II' TIUtK 11-1
~------.... -------------------------~,
_,.,.,/'--------------------------------------------------------------------------------------------
I 1+41 I
______,/
~
I
- +t*
I
.. +**
~----.---------~~~~~--~~~~~----~~.. ~~ ---------
I...,.,
I I..,.
I I
1+ro I
I....
I I..,.
I I
1+#1 I
I.....
I I....
I I
4+41 I
I......
I Log of trench BP-1. Station 3+30 to 4+40 (From Earth Sciences Associates. 1977. figures CJ 0 and CJJ). See Table 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I......
I Gtii.Htt lH II' TN<<N 11-1 I....
I JII*ITM Clf I
I
- fu Figure 4A-l-Sheet 5 ofl8 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
GEHHIC lH N nLiclf.,.,
JTAT/tiN 4#;/l T1 4*H
,.IN/E til
- ---~-------------------------------------------------=---------~-----------------------------------?~-=---==---~-----
~~--------~
I 4+H I
I 4+H I
I 4+H I
I 4+H I
I..,
I
- +**
I..,,
I I
4+10 I
lfEilH" lH If' fiEII'Cif.,.,
JTAfiM ~*II" I*S*
I 4+<1*
I
~~-----------------------------------------'-------------------------__:_~========~~~~~=~===-~~:::=-_:-_=:::::~-=--=-=::::=-----
I 1+41 I
~+**
I.....
I I
I+H I
I I+H I
I,...
I I....
I Log of trench BP-1, Station 4+40 to 5+50 (From Earth Sciences Associates, 1977, figures CJ2 and CJJ). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I I+H I
I 4+H I
Figure 4A Sheet 6 of 18 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
UllHK lll N TNI<<K IY*I JT.tTIM 1*11,. I*H
~=~---~==~----_-_-_-_-__ ~_-_. ___ =-~----
~~~!!.'~~--------------------------------- -
I.
~..
I I
I+H I
I I+H I
I.*..
I I
I+U I
I 6+70 I
-+*-
I 6Ht>
I I
1+11 I
fEilHK lH IF UEIKK IY-1
""'- 1*11 ",.,,
I I+U I
" ~1$
~~~~~~~~~~~~~~~~-~~----------------------------------------~~L----
1 ~~i I *+**
I p f I..,.
I
- +-*
I....
I I
I+A'I I
I
<+H I
Log of trench BP-1, Station 5+50 to 6+60 (From Earth Sciences Associates, 1977, figures CJ4 and CIS). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I..,.
I I.....
I Figure 4A-l-Sheet 7 of 18 m
Humboldt Bay TSFSI Project Technical Report TR-HBIP-2002-01
. Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
r+,.
I I...,.
I I.,.,.
I rf**
I r+u I
I..,
I I.....
I I.....
I I
r+<~l I
I.....
I I
T+4e I
I 'i
I r+1*
I Log of trench BP-1, Station 6+60 to 7 + 70 (From Earth Sciences Associates, 1977. figures CJ6 and CJ7). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I.....
I......
I Gtlllltr tH Ill' T#lllrN U*f
./f~TIIIM 1~61 T# T*IS I
- +u I
"##Itt U#
~lllllft' IN Ill' T#lllrN U*f
./TATII# 1'*" T# T*TI l'ff#lllt'IT I
f +..
I Figure 4A-l-Sheet 8 ofl8 m
Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
~-----..!.-'- -------------------------
I....
I I....
I I
I..,.
I...,
I I 't..
I....
I I....
I,..,,
I Log of trench BP-1, Station 7 + 70 to 8+80 (From Earth Sciences Associates, 1977, figures CJ8 and CJ9). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I,....
I I,.,
I GUlHif lN II' r~Uflf ~1'*1 Jl,IT/6# T*TI T1 ~-11 1'/I,~E til I.....
I
&EilHIC lN IJI' T~EKN N*l JTATIWI I*H n 1*1#
- +u Figure 4A-l-Sheet 9 of 18 rJ Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
- +"
I 'i" I......
I
't" I
>+..
I I '...
I I
P+N I
I t+U I
I 't" Log of trench BP-1, Station 8+80 to 9+90 (From Earth Sciences Associates, 1977. figures C20 and C21). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I, r**
IUlHI( lH N' TI#HN 1'*1 JTATINI,l*ltl Tfl,.,H I 't"
'"'I# ~H IUlltiC lH 4f' TIE#(N U*l JT,,TINf t*.JI 1W,.,,
I 1+..
I
'IIIII Ul I
I.....
I Figure 4A Sheet 10 of 18 m
Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
I "r" I....
I
~+r*
I Ulf I
I.....
I I..,.
I I....
I II+U I
Log of trench BP-1, Station 9+90 to 11 +00 (From Earth Sciences Associates, 1977, figures C22 and C23}. See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
fEiii~IC ill IV TIUNCN 1,_1 JTATINI 1~11 Tl II~
l'lfVIII fll fEiiNI( lll If T#Eif(N P*l JT.tT/IIf I,.H TPI/*11 I'IUAI U4 l.. ft I
Figure 4A-l - Sheet 11 of 18 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
- t**
I
,~... H I
I 1<1+*
I I
N+H I
- +**
I II+N I
J....
I I
"t..
III'N*,_, '"r* *r l*****
Mr*#u """'~,.,. I N*l#
I II+"
I I
u+r*
I Log of trench BP-1, Station 11+00 to 12+10 (From Earth Sciences Associates, 1977. figures C24 and C25). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I H,.
I N+ll I
GUlli/( lH IN' TIIEIIIrK U*l u+u I
1/llHit lH W Til/liCK P*l JTATINI II*# T1 "'II 1'1111/IE tiS I
N+"
I I
11+11 I
Figure 4A Sheet 12 of 18 rJ Humboldt Bay TSFSI Project Technical Report TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
I ti+H I
I 11+11 I
II +H I
II+**
I 18+H I
Log of trench BP-1, Station 12+10 to 13+20 {From Earth Sciences Associates, 1977, figures C26 and C27). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I II+.,.
I
&E#UI/C Ul II' TIL/f&K U*l JT.IT/Nr q*N T1 I~*U I£1LII/C Lll II' THIKK P-1 JTATIIN "'*S TIII*N
,+,.
Figure 4A Sheet 13 of 18 m
Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
,,!~
I I.
I I
I I
I I
I
\\
I
\\
s~t.rr a~,-.l I
I I
I 11+4$
I Log of trench BP-1, Station 13+20 to 13+75 (From Earth Sciences Associates, 1977, figure C28}. See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
IEitHIC lH II' THIIICN IY*I JTATIIJN U_,, 1'1 11-T$
1'11,111 CH I
H+H I
Figure 4A Sheet 14 of18 m
Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 I
II+H I
Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
S:\\51 OOs\\5117\\5117.009\\task_13\\02_0916_s4a\\_fig_ 4A-01-15(40).ai Log of trench BP-1, Station 13+75 to 14+41 {From Earth Sciences Associates, 1977, figure C29), See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
Earth Sciences Associate*
HUMIIOI.DT BAY POWER PLANT $1Tf:
GEOLOGY INVEBTIGATION (19711) tEOt.OGIC Lilt 01' -CH BP-I Figure 4A Sheet 15 of18
I I
I I
"t" I,....
I
... t..
I tf+ll I
I I*+JJ I
&E"HIC lH
- Titli/CK 1/1*1 JT1tr,.,11 ~~~~ r* ~~~
r<<J¥~CM_,....,.~
IT~r/NI ~l*lf T# 14*41 I
U,.HIC t.H
- TALNCJI U*l JT~T/111 N*H T1 IS*~S
'IUIAt r~t Log of trench BP-1. Station 14+41 to 15+25 (From Earth Sciences Associates, 1977, figures C30 and C31}. See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
I fl+<ff Figure 4A-1 -Sheet 16 of 18 10 Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
,l..
I I
IIH*
I
- +*
I II+U I
l I
ll+q I
I
~~r**
I 1>+..
I
~lll~ll l.M IF TIEJI~/1 U*l JTITHII 11"'1 Tl II~S "Hill Ul I
IHJI I
I tS+rJ I
~liiiC~ lU N Tll/HN U*l JTIT/111 IS*U,, If" II I
JStn Log of trench BP-1, Station 15+25 to 16+10 (From Earth Sciences Associates, 1977. figures C32 and C33). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
Figure 4A Sheet 17 of 18 m
Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
I#+*
I "t"
I N.f.N I
Log of trench BP-1, Station 16+10 to 16+45 (From Earth Sciences Associates, 1977, figure C34). See Figure 4-2 for location of trench. Station numbers are in feet measured from the eastern end of trench.
Figure 4A-1 -Sheet 18 oflS m
Humboldt Bay ISFST Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
NE I
- +~I I
I
- +I.J I
I *t'*
mw tiiiTIEASr I
- +16 I
I sw Log southwest of here not shown Geologic log of northeastern part of trench BP-2 (Modified from Earth Sciences Associates, 1977. Figure C37 (colors added for emphasis}].
See Figure 4-2 for location of trench. Station numbers are in feet.
Figure 4A-2 m
Humboldt Bay TSFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
~
Spoil pile contacts not shown ~
(
,.,.,_, lllltrrOO II N **,
Ull.. INIItl f
lllll. "'"a",.,.,....,.. n~~t Mtl ""ta*tNtuJJt.tl.fl(.
- =..~U.fiO/fi.M.I*
,..,tt.,
rll'l/
WEST Geologic log of trench BP-3 [Modified from Earth Sciences Associates. 1977. Figure C37 (colors added for emphasis)}.
See Figure 4-2 for location of trench. Station numbers are in feet.
See Plate 4-1 for location Figure 4A-3 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
~-.....
D 5
LIIIE lAIIt' 6UrfL lltl.:
,IILV CEIIEUU lfA*
fUt'fL IICLIS/1111 tltAUV UAJELU IA/10; IILL; llllf 11 lflllt; 'IA611EIITI IF III.TI tlAV Alii IIIIIITU MAflt tiCK TIIID-ItiT 5
III~IITU SEI.HNTIIIf All' ltRISTIIE liCK FU611fiiTS 15 rtEW EAST
--r--.....:::=='!ii~fKTf lAIIt,UETS,
J~:;::::::;::;;;o-l.fiSfl; ttstiMTIIIIIDIS Geologic log of trench BP-4 (From Earth Sciences Associates, 1977; Figure C35).
See Figure 4-2 for location of trench. Station numbers are in feet.
q IElT Figure 4A-4 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
Z!~'-'**=,,. **"'*'*""'*-~..
(lllfl*
- Uri, riEW IIDlTIWtST Geologic log of trench BP-5 {From Earth Sciences Associates, 1977; Figure C40}.
See Figure 4-2 for location of trench. Station numbers are in feet.
Figure 4A-5 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
FA*nr 11nm*m cur Alii SlT; llllf.
,IC/tW Ill (IAtt IILUIGS " IIU/111 Ifill rt LNif SAil,
- ~::;'j#r~:j,::~:~ IIIII
~~lll~~~.m*r*
~t:ru.~ w~~""
lUI STAUI, CUm LICALLf.
6Uf ctAVEf SILT, 111¥U IIIII STAIN.
t5 II 1111 llllf ITA/lEI IAIIIS Geologic log of trench BP-6A (From Earth Sciences Associates. 1977; Figure C41}.
See Figure 4-2 for location of trench. Station numbers are in feet.
ss so Figure 4A-6 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
Ill/IT FA(( IISI'W IUf*UAr II*
IWIIU lifE UMCM CIIT lD
~~-/
(IIA/11 Tli/IC/1)
FILL TUICUU tfiiU All :
jf'::;~r ;,':!~ i FUCTIU,.. ISI'W i UIII/UTU !ItT Alii curn mr
---~~:-~:~.:~:----:::7,-.......... ------=------~~....... ;*_=_::=:::;:;;;::;==-
1/tTV CUV ll.lfflij um a*a~
~YUf NMD~
- -----~
- .,~
15 Ill VIEW EAST Geologic log of trench BP-68 (From Earth Sdences Associates, 1977; Figure C42).
See Figure 4-2 for location of trench. Station numbers are in feet.
- r.:rti.AIII, !Alii, lila !ItT
'UIU IIWIWAU fO, Figure 4A-7 m
Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 55 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
SltrtTIISIK;IIISE;IlUIIC*
AICI IAU 111111 ZD
,,... ( __ _
W..W/1/H/t//IIQ#'I/d//HI
"" "" U*lrtflrn currr liLT l,.E; CIIJI CIITACT WIAr/111[.
llf£,
IICI IUIIIEIIITS
- fiACrfll WIEI lltiiAifl.,IJIIIT ffli/CAI IIII<ACEMtMr.
Geologic log of trench BP-7 (From Earth Sdences Associates. 1977; Figure C43).
See Figure 4-2 for location of trench. Station numbers are in feet.
fS IITUIIIIlltRr,CIAf..SAII1-IItT111111llt!SWdl IAII,.ATIIIS AMI Ifill!.
mrr UMIIATIIII
""'-., IFrrm llfEtrU flEW IF _,IlliTE WALl lr TIE/ttl AT STAT/Oil 10 Figure 4A-8 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
45
/Mf',.,..,..
"-"#f lilT-- '
-llfTl-U 15 zs Zl 14 VIEW NOll Til WfS T Geol~gic log of trench ~P-8 {From Earth Sciences Associates, 1 977; Figure C44).
See Frgure 4-2 for location of trench. Station numbers are in feet.
Figure 4A-9 Humboldt Bay TSFSI Project
~ Technical Report TR-HBIP-2002-01
/l'l/1111 tJI' M.tiN TIE<<N w... &/,..cw...
l Apendix4A Logs of Site Trenches Rev. 0, September 16, 2002
I I+.,.
I I
1+11 I
I...,.
I YIHt 1/0ITI I
$ -+41 I
Geologic log of trench BP-9 (From Earth Sciences Associates, 1977; Figure C45).
See Figure 4-2 for location of trench. Station numbers are in feet.
I S+.ll I
I 1+11 I
Figure 4A-10 I
1+11 I
rJ Humboldt Bay lSFSl Project Technical Report TR-HBlP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
Depth (meters)
Trench 11-T6a Trench 11-T6b
-olrturbed Soil
-unitS Trench 11*T6b
-unit7
-unitS z
0 f-Z g~
- r:::;;
crcr wo
- u..
g Trench 11*T8c
-unlt5
-unit5 21--
-unlt4 Trench 11*T6c
-Unconformity
-unlt3 Unexposed Section
-oinurbed Soil
-unit2
-unlt1
-Unconformity
-unitF
- za--==
[3]
[f2 E£1 r:t:ill1
~
EXPLANATION SMd (s)
Slit (sltl Silty clri/ciiYeY silt (slt-cl/cl*slt)
Gravel (Gr)
Composite stratigraphic section and description of lithologic units exposed in Site trenches 11-T6a, 11-T6b, and 11-T6c (Modified from: Woodward-Clyde Consultants, 1980, Appendix C).
LITHOLOGIC DESCRIPTIONS UNIT 8: GLEYED SIL TV AND SANDY CLAY Light gray to gray (10 YR 6/1 moist) and strong brown (7.5 YR 5/8 moist); some pebbles; moderately developed ped structures.
UNIT7: SAND Brown to dark brown (10 YR 4/3 moist), dark yellowish brown (10 YR 4/6 moist), and yellowish red (5 YR 4/6 moist); fine-to medium-grained; subrounded; contains some discontinuous silty clay laminae and very thin beds (1 to 5 em).
INTERBEDDED AND INTERMIXED SILT. SAND, AND SIL TV CLAY Pale brown (10 YR 6/3 moist), strong brown (7.5 YR 5/8 moist), and dark gray (2.5 Y N/4 moist).
SILT Strong brown (7.5 YR 5/8 moist), light olive-brown (2.5 Y 5/4 moist), and dark gray (2.5 Y N/4 moist); discontinuous interbeds and lenses of silty clay and fine-grained quartz sand.
SILTY CLAY I CLAYEY SILT Dark gray (2.8 Y N/4 moist); slightly sticky and slightly plastic; many organic fragments, some pyritized.
INTERBEDDED AND INTERMIXED SILT AND SAND Unit fines upwards. Yellowish red (5 YR 5/8 moist) and strong brown (10 YR 5/8 moist); sediment deformation common.
UNIT 6: SILT, SILT WITH SAND LAMINAE, MEDIUM, AND COARSE SAND Unit fines upwards. Strong brown (7.5 YR 5/8 moist), yellowish brown (10 YR 5/8 moist), light olive brown (2.5 Y 5/4 moist). Sediment
. deformation in uppermost silts. Basal pea-sized gravel.
UNIT 5: SILT. SILT AND SAND, FINE AND MEDIUM SAND Unit fines upwards. Light olive-brown (2.5 Y 5/4 moist), and grayish brown (2.5 Y 5/2 moist). Basal pea-sized gravel or sand interfingers with underlying silt.
UNIT 4: SILTY, PEATY SIL TV SAND, SILTY SAND WITH SOME PEBBLES, GRAVEL Unit fines upwards. Dark yellowish brown (10 YR 4/6 moist), yellowish red (5 YR 4/6 moist), light olive-brown (2.5 Y 5/4 moist). and grayish brown (2.5 Y 5/2 moist); abundant organic material at base of silt and within peat layer. Gravel is subangular, poorly sorted and poorly graded; coarse sand size to 30 em; 46 percent chert, 37 percent quartz-rich metavolcanic and metasedimentary rocks, 13 percent quartz, 4 percent graywacke sandstone, 2 percent clay balls, rare sand lenses.
UNIT 3: SAND Olive-brown (2.5 Y 4/4 moist); medium-grained; subrounded to subangular; contains discontinuous thin (2 mm to 4 em) silt lenses.
UNIT 2: SAND WITH SILT INTERBEDS Yellowish brown (10 YR 5/6 moist) and light brownish gray (2.5 Y 6/2 moist): fine* to medium-grained; laminated, some sediment deformation and cross-bedding.
UNIT 1: INTERBEDDED SAND AND GRAVEL Gravel: 1 mm to 15 em; poorly sorted and poorly graded; thinly bedded; 53 percent chert, 23 percent metavolcanic and metasedimentary rocks, 11 percent quartz, 11 percent graywacke sandstone, 2 percent clay balls.
Sand: strong brown (7.5 YR 4/6 moist); massive; medium-grained; subangular.
UNIT F: SILTY CLAY Very dark gray (10 YR 3/1 moist); slightly sticky and slightly plastic; rare shattered sea shells. Grades to interbedded and intermixed silt and sand, sand. Unit fines upwards. Interbedded and intermixed silt and sand is dark brown (7.5 YR 3/4 moist) and dark grayish brown (1 0 YR 4/2 moist). Sand is olive-brown (2.5 Y 4/4 moist); medium-grained; subrounded to subangular; contains some discontinuous, thin (2 mm to 4 em) silt lenses.
Figure 4A-11 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
... "' ~
.r-----------
r--------------~~-~- ----------------
r-------~.-.--- *-------"1..---------'""L..
h~::z-I
~ Q 1
1
- *** * * ***** * **~ ~ ~ * ** *** * "' ' " '
~:>-<-:--:._;.,.c=-------.:~=~~*-"" '" '~'=*:~~~=............... j
{!)o101..,...,.,_
(!).attr....,....
.................. :.::.::::.:::..-""'\\::.:;:;*
<!) _..,...... _
....................... **---.-.. -.. -.. -.. -.<.~.*.**.~*:*~*:*~-~
.:~.*:*~*:_
- ~*:*.~.*:*~*:*~
-:r.-
- '~.~-~.*:...~
- ~.**.**.~.*.:...
-.:.:_.:~~.:.:_.:_~
. *... ~.;.:~:;;_:: I h
- ~:~.~~:~2:-~:*::*~::*:
\\Y Q)oOt Log of trench ll-T6a (From Woodward-Cly de Consultants, 1980, Figure C-29).
See Figure 4-2 for location of trench. Station numbers are in meters.
EXPLANATION lithologic Contact; 101id line~
molutlon Is 1e11 than 2 em. dMhecl line where 2-6 em. clottad line *~
s-1sc.n.
Soil Contact Disturbed Soil Contact Feult;10lld line where mo~tlon
...... /
lsi* t111112 em, dMheclline ~
N=
2-15em,clon.dllne~l-11cm ;
strike end dip of fiUit pi-lndlcatld; al'l'OWIIndicate *n* of relative_.
l'lllllt.
N70W 51'!..--
Strike llld Dip of jointi111
~ She..
Figure 4A Sheet 1 of 4 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
- ~
_r-----
-- L i
- ~-
W w
i i
i I
i r------..:--------------
-~----~-------~--~-----~_[-~~--.:-::.;:::~-==7--~~=~~~~~~r:-::;~:==~~-~~~:~
- -------=~-----~-~~-=- --:-=---;_~~~~~-::~~==i;~~~::~~~=:~~~:~~~~'
l-------
0-"'~"'.,
~'-<i)?i,;:~............................................................. ~
~""'*'*:::c*::::::*. : :'G~=*:::=:::::I
..........r;: ::7:: ::::::*::::::::::*-::.~:*::::: ::*:::::::::::~:::.':'..............................................................................................................
0- ~..
(!)....,..........
! *:::*::: ::::: *;;:.~*;:::\\b.:..... ~*";;;:;7"*
- ?:!/7?:::7:.*'!?5:*::::*:::x:::.:*
- §::::::: :::~:::~.:::: :: ::: ::*:::
Log of trench 11-T6a (From Woodward-Clyde Consultants, 1980, Figure C-29).
See Figure 4-2 for location of trench. Station numbers are in meters.
(!)**.,...,
EXPLANATION Lithologic Contact; solid line w11era molutlonla lea ttl., 2 em, dllhed line.....,. 2-5 em, dofllld line wMra 5-15cm.
Soli Contact
.. --- Disturbed Soil Contlet
- FMIIt;oolld line whe,...solution
...... /
Is *- ttl., 2 em, dllhed line.....,.
N~W 2-5 em, don.d line w11era l-15 em; strike Md dip of fMIIt P'- lndlce1M;
.,_lndlcote senw of,.leti.. -
ment.
N70W
"~
Strike end Dip of joint!,.
~ Shein Figure 4A Sheet 2 of 4 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
i I
I T
T 7
--1
.i T
7 I
T T
i
~ ~-=+/-~~~~-===~--=~~-
' -l (!)~-......
__ j
(!)_...., ________ _
--"!.-----""'1
~.... - *~-********** ***** <!>--
T T
. j T
i
- T I
'i
't I
I :
................................... ~......,
(!)...,.,....
............ *::::::*................. ~................. _............... -....................... ~------------------------
j'~-~~:~=:::~~~::::~;~:::~ :~.-~~~"-~-~-:~=~;;: ::=~~-~=-~:-:;~:: ~,
(!).....,'"'
- .*.::::.:::::~::::'.::~:::.-.:::.~::: ::::::::::~::~~ ~:~*;;,-;~:-....
- 1'""'""""""'""'"**~~~-*"""""' """"**............ _...........
(!)......
.......................... &;.;;;*.;;*~~*-* " " " "'
i i
i
'T *-
1 T
T -
T T
i T
I T
I T
T 7
=~
- --l,,..
F
_r.::/
-=- ---.- -
- .rl ---..,~~---1
--- -'""" ----1
~
fiL __,
---* 0-- I i"'=i
{
L ---------*
(!)-..,..;
I I
I
~~-----=~~~~------........-----------~~-~
.............................................................. _'-----------------i~
~~r~;)
'.!I Log of trench 11-T6a {From Woodward-Clyde Consultants, 1980, Figure C-29}.
See Figure 4-2 for location of trench. Station numbers are in meters.
- r ION N70W A!:!--
EXPLANATION Lithologic Contlet; solid line where resolution is less th1n 2 em, dllhed line whir* 2-5 em, dotted lin. where 5-15em.
SoiiContlet Disturbed Soli Conuc:t F.ult; solid line where resolution Is less then 2 em, d8lhed line where 2-6 em, dotted line where 5-16 em; ltrilce 1nd dip of f.ult plene lndlcat8d; arrowslndlcatB *me of relltlve I'IIOW-ment.
Strike lnd Dip of Jointing Shtn Figure 4A Sheet 3 of 4 rJ Humboldt Bay JSFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
Log of trench 11-T6a {From Woodward-Clyde Consultants, 1980, Figure C-29).
See Figure 4-2 for location of trench. Station numbers are in meters.
EXPLANATION Lithologic ContiCt; solid line.....,.
rosolution Isle* INn 2 em, dashed line.....,. 2-5 em, donod line wlllre 5-15cm.
Soil ContiCt
- - **--- Disturbed Soil Contoct Foult; solid line whoro resolution it I-then 2 em, dashed linowlllre 2-5 em, dotted line whore 5-15 em; strike end dip of I lUll plono indicolod;
- rrowslndlcatt sen* of rttetlve mow*
~'*
N*'~
Strike~ Dip of jointing
- jfo She..
Figure 4A Sheet 4 of 4 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
"<<i 0,_
(;:)
L!)
Vi 0
0
~
<ii 200
~
Q) 1i).s
- r:
I-C..
w Cl Grading to sandy silt.
REFERENCE LEVEL LINE 201 Gray silt and silty clay.
HORIZONTAL DISTANCE (meters) 202 203 Clayey silt with sandy silt small lenses and irregular laminae.
204 Silt with fine sand and silty clay laminae and lenses.
- Clay lnc.reases downward.
Dark gray clayey silt, nor major textural change up or down, slight increll5e in clay content, dark color possibly due to
- organic material." Very diffuse contacts, some pyritlzed organic material.
Figure 4A -13 Detail of stratigraphy in trench 11-T6a at station 7 5. 5 meters (From Woodward-Clyde Consultants, 1980, Figure C-30c).
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
126 127 HORIZONTAL DISTANCE (meters) 128 129 130
.,.~_..,.__.._,.....,.,..--T...,..,...-::::::::::--r-r---~D;Isturbed soil 1
Disturbed soil I
- . 1
~......t**---.1.. *-**---**~ -+---*.---- _........
I I* *: : *.. :*.I I
Silt lens"" 1 an thick*. I L * * * * ' :
.:I I
~
- .*~.*
- Mn02 concentrations.
- I I
.* *~*.;..~~J
- r I * *. * * *1 Strongly oxldiztd zone 3 an from contact.
Fine t~ medium sands, Indistinct bedding.
Nearly horizontal laminae of silt, silty elay 111d fine sand wl1h some Intermixed silt and fine 'lind. S.Od laminae lncreue towards bottom.
Dark gray clayey silt with some silt and
---*bund.llnt organic material (roots, fibrous material, pyritlzed grass).
Figure 4A-14 Detail of stratigraphy in trench 11-T6a at station 128 meters (From Woodward-Clyde Consultants, 1980, Figure C-30b).
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
<i: d
_.I CIJ
""" :I
~I 10 9
M 74 Mn02 concentrations.
Strong oxidation in this horizon.
75 HORIZONTAL DISTANCE (meters) 76 I
I L
GROUND SURFACE I
Disturbed soil 1
1 Disturbed soil I
I 77 78
~~-.. --**--**--**--
Fractures with roots. Material reduced around roots.
Massive silty clay with fine sand. Some COI!rse sand grains and very few small rounded chert pebbles.
Massive silty clay; slightly more clay and slightly* less sand, oxidation, and induration than overlying silty clay.
Same as above but with a distinctive decrease in silt and fine sand and Increase in clay.
Silty fine sand with thin sandy silt beds and lenses. Abundant well preserved grass.
Very thinly laminated clayey silt and silt.
- 1 Figure 4A-15 Detail of stratigraphy in trench 11-T6a at station 200 meters
~
(From Woodward-Clyde Consultants, 1980, Figure C-30a).
(j) 0 0 r-:
m Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
'/-
NOTE:
lOUTH WALL
-M40E See facing page for lithologic descriptions EXPLANATION Lithologic Contact; solid line where resolution is less than 2 em, dashed line where 2-5 em, dotted line where 5-15cm.
Soil Contact Disturbed Soil Contact
~
Fault; solid line where resolution is less than 2 em, dashed line where N75W 2-5 em, dotted line where 5-15 em; 60N strike and dip of fault plane indicated; arrows indicate sense of relative move*
N70W 55N_..,..
ment.
Strike and Dip of jointing Log of trench 11-T6b (From Woodward-Clyde Consultants. 1980, Figure C-33).
See Figure 4-2 for location of trench. Station numbers are in meters.
CD*****
,IN
{!)IINW,Ih (i)........
(!)........
<!>~~ZZW~.tn utw....
Gj1111W,BI Oat*.m
@1*.... -
0*c"...
e...... ~
e.._...
f8..,.., fH
~....... "
8*u-...
SillltW.NI SOUTH WALL
-IJMOE
~......
e*n.**
611tn,101 ftUR,II t 8........
8**-.u*
e*aw,aa 8......
8....,..
8.... -
8....,4ft
@llllft,MI e.......
8*.......
e*.-.**
s.......
- e...._,.,,
8ttt.....
Onn.***
811J.......
8**"'***
e.......
8........
8.,,_,.,,.
@IIII... Ut a.......
e.........
8t~~TW, IIt s...o-.**
8..., *.*.*
8.,.*.*,.
@IU4w,ns Qlf4N,UI 8.,.....
0 IINW,Nl 8 ***.a*
8..... ~.
8........
lOUTH WALL
--N401!
Figure 4A-16 rJ Humboldt Bay TSFST Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
10UTMWAL4.
- ow--..*
--L ______ _
EXPLANATION Lithologic Conuet; solid lirie whtrt rnolution is leu thll'l 2 em, dashed line whlrt 2-5 em, dotted line where 5-15 em.
Soil Conuet Disturbed Soil Contect
~Jii N711W ION N70W 511~
FIUit; tolid line where resolution is less then 2 em, dnhld line where 2-5 em, dotted line where 5-15 em; strike end dip of fault plane indicated; arrows indicete sense of relative move*
rnent.
Strike 1nd Dip of jointing
~,
She..
Log of trench 11-T6c {From Woodward-Clyde Consultants, 1980, Figure C-35).
See Figure 4-2 for location of trench. Station numbers are in meters.
Figure 4A-17 m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Apendix 4A Logs of Site Trenches Rev. 0, September 16, 2002
Seismic Source Characterization of Cascadia Subduction Zone INTRODUCTION Interpretations of the tectonic framework of the Mendocino triple junction region have evolved rapidly during the past few decades as new geologic, seismologic, and crustal structure information has become available. In particular, the characterization of the Cascadia subduction zone has changed dramatically. Prior to the mid 1980s, the Cascadia subduction zone was judged not to be seismically active by the majority of seismologists and geologists, and was interpreted not to have the capability of producing significant earthquakes. As new geologic evidence was identified during the mid and late 1980s, the perception of the capability of the subduction zone changed, and by the mid 1990s, a new scientific consensus that the subduction zone is capable of generating great earthquakes had evolved (Atwater and others, 1995).
Because the scientific community increasingly accepted the Cascadia subduction zone as a potential source for earthquakes, the California Seismic Safety Commission, along with the California Department of Transportation (Caltrans) and the Oregon Department of Transportation, sponsored studies to define the characteristics and assess the consequences of a Cascadia subduction earthquake. In California, the California Division of Mines and Geology (CDMG) prepared a Cascadia earthquake scenario analysis (Toppozada and others, 1995). The CDMG scenario earthquake was defined as a "Gorda segment" rupture, involving slip on the southern 240 kilometers of the Cascadia interface and generating a magnitude 8.4 earthquake 1*
Additionally, the CDMG scenario event included slip on the Little Salmon fault zone that was triggered by slip on the subduction interface. The Little Salmon fault zone was interpreted to be a crustal thrust fault above the Cascadia interface. The scenario earthquake was also considered to be a source for generating a local tsunami.
1 Earthquake magnitudes are moment magnitudes, M, unless otherwise stated.
.. Humboldt Bay ISFSI Project
~&~
Technical Report TR-HBIP-2002-01 5A-1 Appendix SA SSC - Cascadia Subduction Zone Rev. 0, December 27,2002
Since publication of the CDMG Cascadia earthquake scenario (Toppozada and others, 1995),
additional evidence pertaining to the tectonics and seismic source characteristics of the Cascadia subduction zone and the Mendocino triple junction has been discovered, and is either published or in the process of being published. The most significant characteristics that are departures from the previous source characterization models are the following:
The Cascadia subduction zone appears to have ruptured repeatedly from Humboldt Bay north to at least northern Washington (about 1,100 km), producing earthquakes of magnitude 9 (Figure 2-1 ). Several similar great earthquakes have occurred during the past several thousand years, with the most recent one occurring in January 1700 AD.
The Little Salmon fault zone appears to be structurally and kinematically associated with other thrust faults offshore of northern California and southern Oregon (Figure 2-3). This fault system, which is referred to as the Little Salmon fault system in this report, is interpreted to accommodate much of the up-dip slip of the subduction zone, and thus slips simultaneously with subduction zone slip during a great Cascadia earthquake.
The Little Salmon thrust system produces surface deformation consistent with a fault dip of about 45 degrees at depth, and thus can cause large amounts of vertical seafloor displacement capable of generating large, local tsunamis.
Additional sources of large subduction zone earthquakes are interpreted to include the Eel River and Petrolia subduction zone segments south of Humboldt Bay (Figure 2-3, 2-5 and 2-6). The 1992 Petrolia earthquake apparently was independent of the larger and more northerly Cascadia events.
MAIN CASCADIA INTERFACE As described in Section 2.0, there is a consensus among the scientific community that the interface between the Gorda and North American plates (i.e., the Cascadia interface) is seismically active and is capable of generating great subduction zone earthquakes. The Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 5A-2 Appendix 5A SSC - Cascadia Subduction Zone Rev. 0, December 27,2002
occurrence of the 1992 Petrolia earthquake at the southern end of the interface may represent the first observation of a Cascadia interface earthquake (Oppenheimer and others, 1993).
The southern end of Cascadia interface is segmented forming the main Cascadia interface plus two smaller subplates, the Eel River subplate and the Petrolia subplate. The Table Bluff fault is not considered to be an independent source, but rather it is interpreted to be an imbricate thrust in the Little Salmon fault zone at the southern edge of the main Cascadia plate onshore. The Little Salmon fault system is considered to be part of the main Cascadia interface.
Source Geometry The total length of the Cascadia subduction zone from the Mendocino triple junction to the Explorer plate is about 1,100 kilometers (Figure 2-1 ). The main Cascadia interface ends about 50 kilometers north of the triple junction (Figure 2-6).
In the southern part of Cascadia, the main Cascadia interface has an average dip of about 7 degrees. The Cascadia interface becomes the Table Bluff fault, which forms a thrust wedge in the upper several kilometers where it has a southwest dip of about 35 degrees. At greater depth it is northeast dipping. (Figure 3-4).
The discussion of the tectonic framework in Section 2.0 presents evidence that suggests that earthquakes on the main Cascadia zone have had very long ruptures that extend from northern California to at least central Washington or possibly farther north. Currently, there is no data on the timing of past Cascadia earthquakes north of Central Washington. Two rupture segment lengths are considered: a rupture from the Table Bluff fault to Central Washington (700 km), and a rupture from the Table Bluff fault to the Explorer plate (1,050 km). Because there is no evidence to favor one rupture length over the other, these two rupture lengths are assigned equal weight.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 5A-3 Appendix 5A SSC-Cascadia Subduction Zone Rev. 0, December 27,2002
Earthquake Recurrence Intervals The main Cascadia interface has been seismically quiescent during the historical period, thereby precluding the use of seismicity data to constrain the recurrence rate. Consequently, we relied on paleoseismic evidence for earthquake recurrence intervals to estimate recurrence rates on the plate interface.
In previous studies, the recurrence rate has been estimated by balancing the moment rate on the subduction zone, as is typically done for crustal faults; however, the locking factor, "a", needs to be specified. The only data available from which a can be constrained are the paleoseismic data.
This approach does not add any new information that is not already considered from the paleo seismic data directly; therefore, it was not used in this study.
Geologic studies of the timing of coastal subsidence and tsunami deposition are discussed in Sections 2.0, 3.0, and 9.0. These studies provide information on the timing and recurrence intervals between earthquakes. Table 5A-1 gives the dates of the last eight events along the southern part of the Cascadia subduction zone. The mean recurrence interval is 500 years +/-1 00 years. However, the events appear to occur in triplets, with each triplet defining one megacycle.
The total time interval for one megacycle is about 1,400 years. Each megacycle includes an initial event following a long (800 to 900 year) interval and then two events preceeded by short (200 to 400 year) intervals.
PETROLIA SUBPLATE Source Geometry The geometry of the Petrolia subplate is defined by the rupture zone of the 1992 Petrolia earthquake, which had a length of about 18 kilometers, a down dip width of 14 kilometers, and dip of 10 degrees.
Characteristic Earthquake Magnitude The 1992 magnitude 7.1 Petrolia earthquake provides an estimate of the characteristic magnitude for the Petrolia subplate.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 5A-4 Appendix SA SSC - Cascadia Subduction Zone Rev. 0, December 27, 2002
Earthquake Recurrence Intervals Tanioka and others (1995) estimate that it would require 48 years to accumulate the strain that was released during the Petrolia earthquake at their preferred strain rate of 5.6 centimeters per year.
EEL RIVER SUBPLATE Source Geometry The Eel River subplate has a length of about 80 kilometers. The down dip extent is limited by the Eel River syncline (Figure 2-6). The seismogenic thickness is 15 kilometers, the dip angle is 45 degrees, and the down-dip width is 21 kilometers.
Earthquake Recurrence Intervals There is no independent evidence of the recurrence rates of earthquakes on the Eel River segment of the Cascadia interface. Therefore, the recurrence interval of the Eel River segment is assumed to be the same as the main Cascadia interface.
LITTLE SALMON FAULT ZONE AND LITTLE SALMON FAULT SYSTEM Source Geometry The down dip seismogenic width of the Little Salmon fault zone is defined by its average dip and the thickness of the seismogenic crust. Exploratory trenches across two traces of the Little Salmon fault indicate an average dip near the surface of about 25 degrees (Carver and Aalto, 1992). This relatively low dip persists to a depth of at least two kilometers, based on the intersection of the fault in a borehole at the Tompkins Hill gas field (Carver and Aalto, 1992).
However, as described in Section 4.0, the dip of the fault at depth is interpreted to be greater than 45 degrees. The dip at depth controls the width of the fault. Therefore, the following estimates for the average dip of the Little Salmon fault zone were assigned: 40 degrees (0.2), 45 degrees (0.6), and 50 degrees (0.2).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 5A-5 Appendix 5A SSC - Cascadia Subduction Zone Rev. 0, December 27,2002
The thickness of the seismogenic North American crust varies along the length of the fault zone.
At its seaward end, the depth of the seismogenic crust is about 5 kilometers; it gradually increases to 25 kilometers at the southeastern end of the Little Salmon fault. The average seismogenic depth along the entire length of the fault, then, is about 15 kilometers.
The Little Salmon fault zone is considered to be part of an upper plate thrust system that is associated with the Cascadia subduction zone. This thrust system is called the Little Salmon fault system. Offshore, the fault system bends northward, trending parallel to the deformation front (Figure 2-5). The fault system continues north to the Thompson Ridge fault, which demarks a change from oblique crustal shortening on en echelon thrust faults to strike slip bounded rotational blocks. The Little Salmon fault system has a total length of 310 kilometers.
The full length of the Little Salmon fault system is assumed to rupture during the maximum earthquake because it is assumed to be part of a larger Cascadia interface rupture.
The Little Salmon fault zone has several traces in the region near the ISFSI, which affect the assessment of the fault-to-site distance (Figure 2-5). The Little Salmon and Bay Entrance faults are considered to be the primary fault traces that accommodate the main slip. The Buhne Point and Discharge Canal faults are minor splay faults in the hanging wall of the Bay Entrance fault (Section 4.0). They are not considered to be main elements of the Little Salmon fault zone.
Displacement per Event The displacement on the Little Salmon fault zone was computed using the Megathrust model assuming 100 per cent interseismic locking between the plates, and the total strain accrued by convergence of 30 to 40 mm/year was evenly divided among the three events for each megacycle. The Little Salmon fault zone is considered to accommodate half of the total slip on the subduction zone. During a 1400 year megacycle the total subduction zone slip for the three events would be 42 to 56 meters, or 14 to 18.6 meters per event. Slip per event on the Little Salmon fault zone is assigned half of these values, or 7 to 9.3 meters per event.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 5A-6 Appendix 5A SSC - Cascadia Subduction Zone Rev. 0, December 27,2002
Rupture Synchronous with Plate Interface Events Studies of the timing of individual displacement events on the Little Salmon fault zone and comparisons with episodes of subsidence and uplift elsewhere along the Humboldt coastal region led Clarke and Carver (1992) to postulate that the Little Salmon fault zone may undergo slip in conjunction with the plate interface.
The Little Salmon fault system is considered to be part of the Cascadia interface and always ruptures with the interface event (weight for synchronous rupture= 1).
Earthquake Recurrence Intervals The recurrence rates developed for the plate interface are assumed to apply to the Little Salmon fault zone and the Little Salmon fault system.
MAD RIVER FAULT ZONE Source Geometry The Mad River fault zone is a zone up to 10 kilometers wide consisting of at least five major, northwest-trending, northeast-dipping imbricate thrust faults. Field studies focusing on displacement of marine and fluvial terraces have shown them to have a history of late Quaternary slip (for example, Carver, 1987a; 1992; Kelsey and Carver, 1988). Recent preliminary studies have identified a fault, called the Greenwood Heights fault, which intersects the northernmost tip of Humboldt Bay. This fault marks the southern boundary of the Mad River fault zone. The northwestern extent of the zone is based on seismic reflection data (Clarke, 1992), and the southeastern limit of the zone is based on the approximate location of a cluster of seismicity about latitude 40.5°N that appears to crosscut the Mad River trend. The Mad River fault zone extends for a total distance of about 80 kilometers.
The dips of individual faults in the Mad River zone are assumed to be the same as those of the Little Salmon fault zone.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 5A-7 Appendix SA SSC-Cascadia Subduction Zone Rev. 0, December 27,2002
Event Future "Y"
"W" "U"
"S" "N"
"L" "P"
"0" Table SA-l RECURRENCE INTERVALS AND SLIP PER EVENT FOR THE CASCADIA SUBDUCTION ZONE Pacific Gas and Electric Company Humboldt Bay ISFSI Accumulated Strain Slip/event Interseismic Age Interval (ybp)
(yr)
Megacycle W-Future (1 event and counting)
?
300+
300 800 N-W (3 events) 1100 200 1300 300 1600 900 0-N (3 events) 2500 400 2900 200 3100 800
?-0 3900
?
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1
- Megacycle Interval (yr) 1100+
1400 1400
?
SA-8 At 3 cm/yr 33+
9 24 42 6
9 27 42 12 6
24 (m)
(m)
At At At 4 cm/yr 3 cm/yr 4 cm/yr 44+
12 9+
12+
32 24 32 56 14 18 8
6 8
12 9
12 36 27 36 56 14 18 16 12 16 8
6 8
32 24 32 Appendix SA SSC-Cascadia Subduction Zone Rev. 0, December 27, 2002
9 of 8
EMPIRICAL RELATIONSHIP BETWEEN TSUNAMI RUNUP AND EARTHQUAKE SOURCE PARAMETERS by George Plafker, Ph.D.
Plafker Geohazard Consultants 23 5 Highland Terrace Woodside, CA 94062 Prepared for Pacific Gas and Electric Company George Plafker 09/01/02 Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-1 Appendix 9A Rev. 0, August 23,2002
CONTENTS INTRODUCTION.................................................................................. *........................... 4 Purpose.................................................................................................................................................................... 5 Terminology............................................................................................................................................................ 5 Methods................................................................................................................................................................... 6 NEAR-SOURCE TSUNAMI GENERATION.................................................................... 7 CASE HISTORIES FOR SELECTED TSUNAMIGENIC EARTHQUAKES.................... 7 1960 Chile Earthquake........................................................................................................................................... 7 1964 Alaska Earthquake........................................................................................................................................ 9 1991 Costa Rica Earthquake............................................................................................................................... 11 1992 Nicaragua Earthquake................................................................................................................................ 12 1992 Flores Earthquake....................................................................................................................................... 12 1992 Hokkaido Earthquake................................................................................................................................. 14 1994 Mindoro Island Earthquake....................................................................................................................... 15 1998 Aitape (Papua New Guinea)....................................................................................................................... 16 1946 Aleutian Earthquake................................................................................................................................... 16 1994 Java Earthquake.......................................................................................................................................... 17 2001 Southern Peru Earthquake......................................................................................................................... 18 RESULTS..................................................................................................................... 19 Moment Magnitude vs Slip for Tsunamigenic Earthquakes........................................................................... 19 MOMENT MAGNITUDE VS TSUNAMI RUNUP HEIGHTS.......................................... 20 Events Showing Linear Tectonic Tsunami (Truax) Run up/Magnitude Trend............................................... 20 Earthquakes Having Relatively Large Tsunami Run up Peaks (Tpeak) of Unknown Origin....................... 20 Tsunamis with Relatively Large Tsunami Run up Peaks (Tpeak) of Known or Probable Landslide Origin20 Summary............................................................................................................................................................... 21 Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-2 Appendix 9A Rev. 0, August 23, 2002
CASCADIA IMPLICATIONS......................................................................................... 22 Comparison of Model Cascadia event with Historic Tsunamigenic Earthquakes......................................... 22 Tsunamigenic Submarine Landslides on the Cascadia Margin?.*............*...................................................... 22 FIGURE CAPTIONS............................................ ERROR! BOOKMARK NOT DEFINED.
TABLE CAPTIONS.............................................. ERROR! BOOKMARK NOT DEFINED.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-3 Appendix 9A Rev. 0, August 23,2002
EMPIRICAL RELATIONSHIP BETWEEN TSUNAMI RUNUP AND EARTHQUAKE SOURCE PARAMETERS INTRODUCTION
Background
The general association of some earthquakes with tsunamis has been known since ancient times.
Tsunamis have been known in Japan since the beginning of recorded history and a catalog of 177 Japanese tsunamis between 684 and 1984 A.D. provides data on tsunami run-up heights, travel times, damage, and earthquake damage and intensity (Watanabe, 1985). In the Pacific northwest, including northern California, American native oral histories recount earthquake and tsunami events, the last of which was in 1700 (Carver and Carver, 1996), and the context of the histories makes it clear that these peoples were aware of the link between earthquakes and tsunamis long before the last event.
Recently, predicting the amount of tsunami inundation has become a concern as modern society relies more and more on coastal facilities for commerce and living. Estimating potential runups as a hazard is now done for all major coastal installations, such as nuclear power plants, liquefied natural gas loading facilities, and major harbor installations. To help address the problem scientists and engineer s have gathered physical information on historical tsunamis and on prehistoric tsunamis (paleotsunamis ). Recently computer models have been designed to assess the potential hazards, either regionally, such as Bernard and others, 1994, Meyers and others, 1999, or for specific coastal facilities, harbors, and communities.
In order to help assess the potential tsunami at PG&E' s Humboldt Bay ISFSI site in Humboldt Bay, data for historical earthquakes worldwide was reviewed and the important events summarized. The data was then analyzed for empirical relationships and the results used to assess the potential run up heights for tsunamis generated by the Cascadia subduction zone on the northern California coast at Humboldt Bay.
The Cascadia subduction zone is a potential source of large tsunamigenic earthquakes related to slip on the megathrust and on subsidiary faults within the upper plate. Paleoseismologic data along the northern California coast have been interpreted as indicating at least 6, and possibly 7, tsunamis in approximately 3,000 years before present, with the last event about 300 years ago (Carver and others, 1998). Geologic estimates by Carver and others (1998) further suggest maximum run up heights for these tsunamis of 8-19 m in northern California and about 10 m along the coast at the ocean side of the Humboldt Bay spit.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-4 Appendix 9A Rev. 0, August 23, 2002
The potential tsunami hazard to facilities at the Pacific Gas & Electric Company Humboldt Bay Power Plant site can be modeled, but the runup and current velocities obtained at coastal sites from modeling depend heavily on input parameters used for the tsunami source. In particular, the fault slip and the area affected by vertical coseismic displacements of the sea floor, together with the bathymetry, control tsunami runup at specific sites on the adjacent coasts. Because there have been no large historic tsunamigenic earthquakes on the Cascadia subduction zone, appropriate assumptions have to be made regarding earthquake mechanism, size, and expected sea floor deformation.
Purpose This study was undertaken to help constrain input parameters for a plausible tsunami source in southern Cascadia by comparison with all large historic tsunamigenic earthquakes worldwide since 1943. Included in this group are those events for which the faulting mechanism is understood, the moment magnitude and fault slip have been calculated, and for which observational data are adequate to characterize the tsunamis such as local tsunami runup, arrival times, and coseismic shoreline displacement.
For most of the tsunami genic earthquakes, the associated tsunamis are primarily generated by large-scale coseismic vertical tectonic displacement of the sea floor. However, in some events, such as the 1946 Aleutian, 1964 Alaska and 1991 Flores island earthquakes, by far the highest runup was from local waves associated with earthquake-triggered submarine landslides. Other tsunami genic earthquakes in which there are local areas of very high run up but no known underwater landslides, most notably the 1992 Hokkaido earthquake, are clearly anomalous when compared to the majority oftsunamigenic events for which good data are available. For some earthquakes considered to be tsunamigenic most notably the 1994 Mindoro Island strike-slip earthquake, both the earthquake mechanism and the wave distribution and runup point to a landslide, rather than tectonic, origin. Analysis of the worldwide data supports the hypothesis that large submarine slides that occur as a secondary effect of earthquake shaking are probably far more common than has been generally recognized.
Terminology The term tsunami does not have universal meaning, something that has resulted in a remarkable amount of confusion and imprecision in the literature because it has been applied to waves generated by a host of sources. As used here, tsunami refers to the general class of impulsively generated waves that are usually, but not necessarily, associated with earthquakes. Seismic sea wave is a term that specifically refers to long-period tsunami caused by large-scale earthquake-related displacement of the sea floor and characteristically propagate for hundreds to thousands of kilometers. The term landslide-generated wave is used to describe more local tsunami generated by submarine or subaerial landslides.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-5 Appendix 9A Rev. 0, August 23,2002
A tsunamigenic earthquake is any earthquake that generates a tsunami. Tsunamigenic earthquakes are most commonly caused by slip on thrust faults in arc subduction zones and in back arc tectonic settings. The terms "slow" or "tsunami" earthquake are used to describe earthquakes for which the moment magnitude is significantly greater than the shear wave magnitude due to slow rupture velocity. These have been attributed to generating tsunamis that have disproportionately higher run up than "normal" earthquakes of comparable shear wave magnitude (Kanamori, 1972). However, this relationship can only be confirmed for two events in my analysis.
Terms used for wave height are also ambiguous. Rigorously defined, wave height is the distance from crest to trough of the wave before it runs up on the land. Runup height or elevation is the highest altitude above tide level or some other datum (such as mean sea level or extreme high tide level) that the water reaches as it runs up on the land. Comparison of run up heights requires information on the tide stage at which the wave arrived and the vertical coseismic displacement of the shoreline at that site, information that is seldom available. Tsunami maps show graphical or numerical plots of measured wave runup for tsunamigenic earthquakes at near-source coastal sites.
Methods For this study, I have compiled near-field tsunami runup data, coseismic vertical displacement data, and seismologic data for selected better-described large tsunamigenic earthquakes.
Included are:
o Compilation of unpublished tsunami run up maps, and relevant data on coseismic vertical shoreline displacements, and wave arrival times for the 1960 Chile, 1964 Alaska, and 1991 Costa Rica earthquakes (Tables 1-3; Figures 1-3) and a new tsunami runup map for the 1946 Aleutian earthquake (Fig. 9).
o Analysis of tsunami histories and tsunami run up maps for the 1946 Aleutian, 1960 Chile, 1964 Alaska, 1991 Costa Rica, 1992 Nicaragua, 1992 Flores Island, 1994 Hokkaido, 1993 Mindoro Island, 1998 Papua New Guinea, 1946 Aleutian, 1994 Java, and 2001 Peru earthquakes (Figs. 1-11 ). These events were chosen for analysis because they include some of the largest and best-studied earthquakes, or because they illustrate the effects of complexities on tsunami generation and runup, such as landslides, "slow" earthquakes, differential slip at the earthquake source, intraplate faults, and topography.
o Summary of critical earthquake source parameters, particularly calculation of seismic moment and seismically determined slip for 35 of the largest tsunamigenic earthquakes since 1943 (Table 4; Figure 12)
Synthesis of relevant data on tsunami runup for 35 tsunamigenic earthquakes (Table 5) and derivation of and empirical relationship between maximum tsunami run up versus earthquake magnitude (Fig. 13).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-6 Appendix 9A Rev. 0, August 23,2002
The data used focus on tsunamis generated by tectonic displacement and on submarine landslides. Data for tsunamis generated by other sources such as subaerial landslides, meteorites, underwater explosions, and volcanic explosions are not included because they do not apply to the potential for tsunamis generated by earthquakes on the Cascadia subduction zone.
NEAR-SOURCE TSUNAMI GENERATION The rate and amount of vertical displacement of the seafloor, whether by tectonic displacement or gravitational sliding, are the critical factors in generation of earthquake-related tsunamis.
Unfortunately, the vertical component of displacement in offshore subduction zones and back arc settings have rarely been well defined by fieldwork, geodetic data, or seismologic data. Recent advances in the capabilities of the WWSN and GPS networks, have resulted in greatly improved capabilities for determining fault parameters in most parts of the world.
Among the earthquake source parameters evaluated by Geist (1998), the magnitude of slip and the spatial variations of slip have the dominant effect on excitation of near-source tectonically-generated tsunamis. Our data indicate that both average fault slip and maximum regional tsunami runup correlate generally with earthquake size as measured by seismic moment or earthquake magnitude-but only after removal of those tsunamis caused by large earthquake-triggered submarine landslides.
CASE HISTORIES FOR SELECTED TSUNAMIGENIC EARTHQUAKES In this section we briefly review data for selected tsunamigenic earthquakes that provide insights regarding mechanism of tsunami generation and, in particular, problems involved in distinguishing between tectonic versus landslide or other origins for the near-source waves.
Tsunamigenic events discussed are the 1960 Chile, 1964 Alaska, 1991 Costa Rica, 1992 Nicaragua, 1992 Flores Island, 1994 Hokkaido, 1993 Mindoro Island, 1998 Papua New Guinea, 1946 Aleutian 1994 Java, and 2001 Peru (Figures. 1-11).
1960 Chile Earthquake The 1960 Chile Mw 9.5 earthquake was the greatest instrumentally recorded earthquake in the world. It occurred near the southern end of the Peru-Chile continental margin arc where it ruptured a segment of the megathrust between 900 and 1200 km long and 150 to 300 km wide down dip (Figure 1). The earthquake produced the largest and most destructive trans-Pacific tsunami modern times and a near-source tsunami with runups of 10 to 15m along some 550 km of the Chilean (Sievers and others, 1963; Platker and Savage, 1970). Within Chile, the earthquake and tsunami took more than 2,000 lives and caused an estimated $550 million in property damage. The transoceanic seismic sea waves killed an additional230 people and caused an estimated $125 million in Japan, Hawaii and the Philippine Islands.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-7 Appendix 9A Rev. 0, August 23, 2002
The 1960 main shock was the culmination of a complex seismic sequence that lasted 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br />.
Details on the 1960 earthquake mechanism and, in particular, the dip angle, down dip extent, and slip on the causative fault and seismic moment are poorly determined (Table 4 ). Kanamori and Cipar (1974) estimated the seismic moment to be 2.7 x 1023 Nm with an average dislocation of 24m; the main shock moment was later revised by Kanamori (1977) to 2.0 x 1023 Nm* In summary, the geodetic data suggest average slip between 8 and 20 m and a seismic moment close to 1.0 x 1023 Nm whereas More recent seismologic investigations indicate average slip in the range of 19 to 32m and moment of 1.0 to 3.2 x 1023 Nm depending upon assumptions regarding dip and width of the fault surface (Cifuentes, 1989; Linde and Silver; 1989).
A best-fit uniform slip dislocation model of the horizontal and vertical tectonic displacements suggests average slip of about 20m on a fault plane 850 x 130 km, dip ~20° and moment 0.6 to 1.2 x 1022 Nm (Plafker and Savage, 1970). Using a variable slip dislocation model for a fault 900 km long and 150 km wide, Barrientos and Ward (1990) obtained average slip of8 m, local concentrations of slip to 41 m, average dip of 15° to 25°, and total moment release of 9.5 x 1022 Nm; a uniform dislocation model for these same data yields 17 m average slip and a moment of 9.4 x 1022 Nm. In summary, the geodetic data suggest average slip between 8 and 20 m whereas the seismologic data indicate average slip in the range of 19 to 32 m and maximum slip is 40+ m.
The earthquake was accompanied by regional coseismic uplift of at least 5. 7 m, subsidence of as much as 2.3 m, and large transverse horizontal displacements in a seaward direction (Figure 1 ).
The tsunami was generated by tectonic uplift of roughly 10,000 km2 of the continental shelf and slope. In the near field, measured tsunami runup heights of 4 to 15 m were measured along some 850 km of the outer coast, on offshore islands, and in the southern archipelago (Fig. 1, Table 1 ).
Wave run up was 3 m or less in inland waters of the Golfo de los Chonos adjacent to the southern part of the earthquake source region (Nos. 1-3, 5, 6).
The 15 m maximum tsunami run up height is within the range of geodetically calculated average slip on the megathrust (8-20 m) and it is considerably less than the range of seismologically determined slip (19-32 m). The vertical component of slip, assuming it is all on the megathrust and average near-surface dip is 20°, about 3 to 11 m. Dislocation modeling of the coseismic vertical displacement data suggests that a subsidiary reverse fault, with an average dip of approximately 40° splays off the southern part of the megathrust and breaks through the upper plate to the surface near the edge of the continental shelf in the southern part of the tsunami source region (Plafker and Savage, 1970). For a subsidiary fault that accommodates most 75%
of the dip slip (as occurred in 1964 Alaska earthquake), the vertical component of uplift near the shelf edge could be 5.5 to 19m and for maximum slip and (or) steeper dips it could be twice as much. Uplift at the tsunami source in the upper part of this range is capable of producing the runup observed.
Hatori (1966) used the tsunami energy calculated from circum-Pacific tide gages to derive an average vertical displacement at the tsunami source of 5.7 to 10m over a source area of 138,000 km2 (based on the offshore focal region). These results are significant because they indicate that large submarine uplifts of the type postulated for the southern part of the source region must have occurred over most of the region to generate the tsunami that was recorded throughout the Pacific Ocean basin.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-8 Appendix 9A Rev. 0, August 23,2002
Surprisingly for the size of this event, no landslide-enhanced tsunamis are evident in the data. In part this may be because sediment supply to the continental shelf and slope is low and deep water near shore is unusual. Any slide-generated waves that originated off the shelf were likely to be obscured by the ubiquitous tsunami that was generated there by tectonic uplift. Submarine slides that have gone unreported may have well have occurred in the sparsely inhabited southern archipelago area where very few measurements of wave run up were made.
Although many puzzling aspects of the 1960 Chile earthquake remain to be resolved, it is clear that the tsunami generated by the largest earthquake in recorded history was tectonic in origin and that the 15 m measured maximum runup heights are reasonably compatible with known and inferred tectonic uplift on the continental shelf.
1964 Alaska Earthquake The great 1964 Alaska Mw 9.2 earthquake, the second largest instrumentally recorded earthquake in the world, was located at the eastern end of the Aleutian arc where the arc extends obliquely onto the North America continental margin (Figure 2; Table 2).
The earthquake and waves took 129lives and caused more than $300 million damage. In Alaska, nine deaths were attributable to structural failures and subaerial landslides. The other deaths and property damage in Alaska were from slide-generated waves (85) and seismic sea waves (20). In coastal areas from British Columbia to northern California the seismic sea waves took 15 lives and caused extreme damage locally.
The earthquake was generated by rupture of a segment of the Aleutian megathrust that is about 650 km long and 175 to 290 km wide down dip. Displacement occurred along the megathrust at least two subsidiary splay thrust faults that broke through the upper plate at Montague Island and the adjacent continental shelf to the southwest. Dip of the megathrust averages 9° and average dip slip has been estimated from seismological data as 8.6 and 12.1, with maximum slip of 18m (Table 2). Two splay faults exposed on Montague Island dip 50 to 85° and have maximum measured dip-slip of 7.9 and 6.0 m. At least one additional active splay fault is inferred near the edge of the continental shelf based on 3.5 m coseismic uplift and landward tilting of Middleton Island. The measured horizontal and vertical coseismic displacements, together with faulting, suggest that maximum slip is more than 20 m, and possibly as much as 30 m in the northern part of the displacement field (Plafker, 1972).
Seismic Sea Waves Coseismic uplift over some 120,000 km2 of the continental shelf and slope generated a major seismic sea wave train (tsunami) having a period of about 50 minutes (Plafker, 1969).
The first wave arrivals at inhabited sites along the Gulf of Alaska coast were recorded by residents some 19-20 minutes after start of the earthquake. Arrival times indicate that the wave source corresponds with a well-defined zone of intraplate splay faults and maximum uplift that extends SW from Montague Island offshore at least 450 km to the southern Kodiak Islands.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-9 Appendix 9A Rev. 0, August 23, 2002
Near field measured run up heights, corrected for vertical tectonic displacements that accompanied the earthquake, range from 3 to 12.7 m, and runup of 10 to 12.7 m occurred at widely separated sites along some 500 km of this sparsely inhabited coast (Fig. 2, Table 2).
Maximum runup height of 12.7 m is close to the probable average slip on the megathrust. This is also close to the measured vertical component of coseismic uplift at the tsunami source (11.3 m) and its inferred offshore extension. Along Shelikof Strait on the inland side of the Kodiak Islands group, recorded runup was 2.8 m or less indicating significant damping of the wave amplitudes in the more enclosed water bodies. Compared to the 1960 Chile earthquake, runup was more variable, possibly reflecting the considerably more irregular bathymetry and configuration of the glaciated outer coast of the Kenai Peninsula and Kodiak Islands.
Submarine Slide-Generated Waves The 1964 Alaska earthquake triggered numerous submarine and subaerial landslides and associated short-period local waves ("tsunami") along the walls of the steep-sided fiords that indent the shores of Prince William Sound and the coastal mountains to the southwest of the sound (Kachadoorian, 1965; Coulter and Migliacci, 1966: Lemke, 1967; Plafker and others, 1969). Comparable underwater slides and waves also occurred in some of the large glacial lakes, most notably in Kenai lake (McCulloch, 1966). The slides were concentrated mainly in unstable, poorly consolidated delta and glacial deposits, but undoubtedly involved bedrock at some localities.
The resulting waves, which were the main cause of earthquake-related damage and loss of life from the earthquake, were generated during or immediately after the earthquake. These landslide-generated waves had completed their destruction long before arrival of the seismic sea waves generated by coseismic uplift of the continental shelf. Run up was extremely variable with heights at scores of localities above 10 m, tens of sites above 30 m, and the highest measured run up was close to 52 m in Valdez Arm. This slide-generated runup is as much as 4 times higher than the highest runup (12.7 m) attributable to the tectonically generated tectonic tsunami (#2, Fig. 2) and it is the highest runup documented for a submarine slide wave.
Lessons learned from the Alaska earthquake include:
Splay faults are an efficient mechanism for generating regional tectonic tsunamis and that the steeper the fault dip the higher the tsunami for a given amount of slip; Maximum wave runup along irregular open coasts approximates measured maximum tectonic uplift and the calculated average slip on the fault source from seismologic data; Earthquake-triggered landslides near shore are ubiquitous is poorly consolidated deposits and areas of steep underwater slopes such as are present in fiords and rugged mountainous coasts; Waves generated by submarine slides can be violently destructive within a few kilometers distance of their origin and they attenuate rapidly away from the source; Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-10 Appendix 9A Rev. 0, August 23, 2002
Submarine slide generated waves can be almost any height up to a maximum of 4 times the highest runup of a tectonic tsunami; and Both the submarine slide failures and the waves they generate are inherently extremely dangerous to coastal residents and property because they commonly occur in unstable fiord deltas which are the preferred areas for locating coastal communities and port facilities; Because landslide-generated waves can strike so quickly after start of an earthquake, the opportunity for residents to escape to higher ground is drastically reduced relative to the tectonic tsunamis-in Alaska, they accounted for 85 of the 105 deaths attributable to waves.
1991 Costa Rica Earthquake The 1991 Costa Rica Mw 7.5 earthquake occurred by rupture of a back arc thrust fault 80 km long and 40 km wide that dips about 30° landward on the Caribbean Sea side of the Middle America arc (Figure 3; Table 3). The earthquake and tsunami caused 75 deaths, 563 injuries, and left nearly 10,000 people homeless along the Caribbean coast of Costa Rica and northern Panama. This earthquake is of interest here because the generally smooth and gently sloping sea floor together with a dominantly linear low-lying coast precludes the possibility of large earthquake-triggered landslide waves and large wave amplification effects of topography. In addition, coseismic vertical displacements have been measured along the coast so that corrections for tectonic displacement could be made for the measured runup heights (Fig. 3, Table 3) and tidal fluctuations are so small that they need not be considered.
The earthquake occurred on a shallow back arc thrust fault that dips southwest beneath the coast of Costa Rica and the Middle America arc (Plafker and Ward, 1992). Combined geodetic and seismologic data suggest that the main rupture is 40 km 80 km long by 40 km wide and that it dips landward at 30-38°. Measured vertical uplift along the coast increases gradually from 30-40 em in the south to 1.6 m near the northern end near where the fault trace intersects the coast at a structural and topographic high. The dislocation models suggest 2.2 m average slip on the causative fault, and the average vertical component of slip averages 1.1 to 1.4 m.
Measured tsunami runup heights range along 80 km of coast near the earthquake source for all measurements except one range from 0.65 to 1.55 m-equal to, or less than, the maximum measured shoreline uplift of 1.6 m. At one locality, runup reaches 2 meters, 1.25 maximum measured uplift or 1.4-1.8 times the calculated average coseismic uplift (Table 3).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-11 Appendix 9A Rev. 0, August 23,2002
In summary, the 1992 event is of interest because if provides data for the relationship of maximum run up to the vertical component of fault displacement for a tectonic tsunami that is not unduly complicated by landslides, unusual bathymetry, or irregular configurations of the coast.
Like the great 1960 Chile and 1964 Alaska earthquakes at the opposite end of the magnitude scale for tsunamigenic earthquakes, run up heights are is less than average fault slip and they are close to maximum measured uplift.
1992 Nicaragua Earthquake The 1992 Mw 7. 7 earthquake, which was generated by slip on the Middle America arc megathrust off the coast of Nicaragua, is shown as an example of a "slow" earthquake for which excellent source and runup data are available (Fig. 4). Seismologic data indicate average fault slip ranging from 0.5 to 1.3 m, maximum slip of 10m, and a fault dip of 10° (Table 4). Average near-source tsunami run up averages about 6 m with two broad peaks of run up to about 8 and 1 0 m (Table 5).
For this event, maximum vertical displacement is 1.8 m, based on the maximum value for slip and the fault dip. Thus, runup is 4 to 6 times larger than the vertical component of displacement at the tsunami source, assuming that the slip is entirely on the megathrust. This large difference between vertical component of slip and run up height contrasts markedly with those deduced for the 1960 Chile, 1964 Alaska, and 1991 Costa Rica events described above for which the run up height of the tectonic tsunamis is close to vertical tectonic displacement.
One proposed explanation for this discrepancy is non-uniform slip distribution along strike so that areas of highest moment release along the fault would match the somewhat bimodel distribution of the highest tsunami run up (Geist, 1998) much more than the 10 m maximum displacement on the megathrust. Alternative explanations for the runup heights and distributions are that two or more very large earthquake-triggered submarine landslides occurred on the continental slope or that partitioning of slip onto steeply dipping splay faults in the upper plate occurred in the areas of high moment release. Existing data do not allow for a choice between the various alternatives.
1992 Flores Earthquake The 1992 Flores Island Mw 7.5 tsunamigenic earthquake accompanied rupture of a segment of the Flores fault in the backarc region of the Indonesia island arc (Fig. 5). The shaking and tsunami resulted in 1,974 deaths, 2,126 injuries, and $80 to $100 million property damage; about half of the death toll and damage is attributed to the shaking and half to the tsunami.
The earthquake involved rupture of a segment of the Flores thrust fault about 100 km long by 40 km wide that dips southward beneath the Indonesian arc. Coseismic vertical shoreline displacements of as much as 1.05 m help to constrain the earthquake mechanism, and the tsunami run up heights have been well determined from field studies (Fig. 5). Dip of the causative fault is about 40° and average slip is about 3.2 m. The calculated maximum vertical component of slip is about 2.4 m assuming uniform slip on the Flores thrust (Plafker, 1997).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-12 Appendix 9A Rev. 0, August 23,2002
The tsunami exhibits both a regional component (tectonic) of observed run up heights ( <5 m) roughly compatible with computed run up heights, as well as local areas of higher run up (to 26 m) that are significantly larger than computed heights (Fig. 5). The lower runup occurs in the western part of the source region where topography both onshore and offshore is relatively subdued and at most offshore islands. Much more variable and higher runup occurs in areas of rugged submarine and subaerial topography that characterize much of the coast of Flores Island and Babi island in the eastern half of the affected area.
Most of the anomalously high run up areas in the extreme eastern part of Flores island are known to result from submarine landslides or combination submarine and subaerial landslides (Y eh and others, 1993; Plafker, 1997) and many other slides for which nearshore evidence is lacking undoubtedly occurred elsewhere. Along these coasts, fringing coral reefs up to a few hundred meters wide drop precipitously into water depths of 200 meters or more and there was abundant evidence for earthquake-related rock falls, extensional cracks, and landslides along the reef fronts (Plafker, 1977). Maximum runup in the western region is about twice as large as average vertical fault displacement (2.4 m), whereas for known landslide-generated waves it is nearly 11 times higher (Fig. 5).
Evidence for a landslide origin of the highest run up on Flores and adjacent islands typically includes one or more of the following features in the immediate vicinity:
Visible landslides and rock falls occurred along shorelines having steep subaerial and submarine slopes; Local segments of fringing coral reefs were visibly cracked or destroyed by landslides; Shoreline vegetation and facilities showed directional damage, indicating that waves radiated away from point sources at or near the shoreline; Eyewitness's reports of movement of large waves parallel to the shoreline during or immediately after the earthquake; High and destructive waves arrived at coastal communities during or immediately after the earthquake. SCUBA divers mapped areas of extensive damage to the generally sheer reef walls ofBesar, Babi, and nearby small islands north of Flores Island that they attribute to underwater rock falls and landslides at the time of the earthquake.
For this event, the data suggest that the local high (to 26m) and variable tsunami runup throughout the eastern half of the source region was caused by numerous submarine and combination subaerial and submarine slides that were triggered by earthquake shaking. These slide-generated waves were subsequently followed by a tectonically generated wave train that had run up less than ~5 m throughout the region.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-13 Appendix 9A Rev. 0, August 23, 2002
1992 Hokkaido Earthquake The I992 Hokkaido Mw 7.7 to 7.9 tsunamigenic earthquake ruptured a complex of at least 3 thrust fault segments that total I 00 to I20 km long by 30 to 60 km wide in the backarc region of the northern Japan island arc (Satake and Tanioka, I995; Somerville, I995). The earthquake and tsunami caused 23I fatalities on Okishiri Island of which 208 deaths were attributed to the tsunami. Property losses on Okishiri and Hokkaido Islands have been estimated at $1 billion primarily due to tsunami and fire damage (Bernard, Gonzales, and Sigrist, I995).
\\
Based on seismological data, the fault zone trends north-south and has variable dip directions and angles; the northern segment dips east at a low angle and has 2 m of average slip whereas two longer southern segments dip west and have average slip of 2-6 m (Satake and Tanioka, I995). Dip of the causative fault, as interpreted by several investigators from seismological data, range from 25 to 45°. Assuming maximum values for slip and dip, the average vertical component of sea floor displacement at the tsunami source can be no more than 4 m.
Detailed studies indicate that tsunami run up along the coast of Hokkaido and all but a small segment of Okushiri Island and western Hokkaido Island had wave runup of I2 m or less. This is up to 3 times larger than the maximum vertical component of slip at the tsunami source (Fig.
6). By contrast, a 20 km long portion of the south end of Okushiri Island was swept by waves that had runup of I5 to 32 m, or 8 times the vertical slip component.
The exceptionally high run up has been attributed to the close proximity of the wave source to the south end of Okushiri Island and to near-shore wave amplification by submarine and subaerial topography (Matsuyama and Tanaka, 200I; Satake and Tanioka, I995; Titov and Synolakis, I997). The wave directions from the northeast and east at the southeast tip of the island were attributed by investigators to refraction of waves as they propagated around the south end of the island from a source region west of the island (Hokkaido-Nanseki-Oki Earthquake Reconnaissance Team, I995).
Experimental flume modeling of the pocket beach where maximum run up occurred (Matsuyama and Tanaka, 200 I) and numerical analysis of the entire region using a shallow water wave approximation model (Titov and Synolakis, I997) appear to adequately reproduce the regional tsunami run up for a source wave of about 4 m. If the assumed source uplift and the modeling are valid, this is the only tsunamigenic earthquake for which run up height is as much as 4 times maximum coseismic vertical displacement at the source.
Despite the intensive investigations into this event, some of the data suggest to me that submarine slide-generated waves probably caused some or all of the exceptionally high run up on southern Okishiri Island. A possible landslide origin is indicated by the following:
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-I4 Appendix 9A Rev. 0, August 23, 2002
The highest runup areas coincided with unusually steep coastal and offshore topography; Large onshore landslides were triggered by the earthquake in the same general area; Shorelines in areas of highest run up were inundated within minutes after the earthquake suggesting a nearby sources; and Reports by investigators that the early waves that struck the southeast tip of Okishiri Island came from the NE, on the opposite side of the island from the tsunami source and with the opposite sense of predicted movement for tectonically-generated waves.
1994 Mindoro Island Earthquake The 1994 Mindoro island Mw 7.1 earthquake occurred within the Philippines island arc by rupture of at least 35 km of the Aglubang dextral strike-slip fault on northern Mindoro Island and offshore beneath Verde Island Passage (Fig. 7). The earthquake generated a tsunami that devastated several small villages on northern Mindoro Island and on several offshore islands with loss of at least 58 lives (PHIVOLCS, 1994; Wells and Porazzo, 1994).
Measured onshore fault slip was 3.45 m horizontal with a local vertical component of as much as 1.2 m near the southern end of the rupture. Shortly after the earthquake, a tsunami struck parts of the coast of northern Mindoro Island, local areas of southern Luzon Island, and small islands in the intervening Verde Island Passage. Data on run up heights, which reach 7.3 m on Baco Island, and inferred direction of wave travel are shown on Figure 7. There are no reports of coseismic vertical tectonic displacements of shorelines, and none are to be expected for this small dominantly strike-slip event.
The data indicate to me that the tsunami that followed the earthquake were caused by multiple submarine landslides, the largest of which was located near the epicenter in South Pass off the Aglubang River delta. Other possible submarine landslide sources could account for the tsunami runup on Luzon Island near Lobo and possibly in Batangas Bay.
A landslide interpretation is supported by:
Topography characterized by steep and irregular volcanic shorelines along which large subaerial landslides were triggered by the earthquake; Reports by fishermen of upwelling water and bubbles after the earthquake offshore from Baco suggesting that one or more submarine slides from river deltas in the area released methane entrapped in the sediments; The generally radiating pattern of wave movement directions from an offshore area southwest of Baco Island, that suggests one or more point sources as would be expected for submarine landslides on the Aglubang River delta; and Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-15 Appendix 9A Rev. 0, August 23, 2002
(4) Arrival of the waves within 2-5 minutes of the earthquake indicating near-shore wave sources.
There are no data to support the interpretation that the tsunami was somehow directly related to tectonic displacement on the Aglubang fault as suggested by Imamura and others (1995).
1998 Aitape (Papua New Guinea)
The 1998 Mw 7.1 Aitape earthquake (also referred to as Papua New Guinea earthquake) occurred south of the New Guinea Trench that marks the plate boundary between the Australian plate on the south and the obliquely underthrusting ocean crust of the North Bismark Sea plate to the north. The seismologic data indicate that this was a "slow" earthquake on a 40-km long reverse fault with steep south dip and average slip of 2.15 m (Geist, 1998).
The earthquake was followed within 11 to 19 minutes by the arrival of three successive waves along a 40-km segment of the northern coast ofNew Guinea (Fig. 8). Maximum runup of 10 to 15 m in a 14-km segment of coastline was centered on the villages of Arop, Warapu, and Nimas along the margins of Sissano Lagoon (Fig. 8). The tsunami obliterated all three villages, resulted in about 2,200 deaths, 1,000 serious injuries, and left some 10,000 people homeless; there were no casualties reported due to earthquake shaking.
Tsunami run up for this event is unusually large for the magnitude. Despite intensive research into all aspects of this event, the source of the tsunami remains controversial. It has been attributed to either a steep offshore fault (Geist, 1998; Hurukawa and others, Satake and Tanioka, 1999; etc.) or a massive sediment slump (Tappin and others, 2001; Synolakis and others, 2002; etc.). Results of extensive marine surveys reveal a recently active submarine landslide with an area of ~25 km2 offshore from Sissano Lagoon that can account for the tsunami arrival time and runup distribution along the adjacent coast. In contrast, the surveys in the possible tsunami sour9e area have not found any evidence of faulting adequate to generate the observed tsunami runup heights and in a location consistent with the wave arrival time.
1946 Aleutian Earthquake The 1946 Aleutian earthquake (Mw 8.6) was situated ~ 150 km offshore from Unimak Island along the inner wall of the Aleutian Trench (Fig. 1 ). This event is unique among tsunamigenic earthquakes in that it generated both very high near-field runup (to 43 m) and a very large and destructive trans-Pacific tsunami that caused extensive damage and casualties in the Hawaiian Islands (to 16 m) and other South Pacific islands (Shepard and others, 1946). With an Mw of 8.2 and Ms of only 7.4, it is a classic "slow" or "tsunami genic" earthquake (Kanamori, 1972).
Aftershock data indicate that the earthquake was generated by rupture of a segment of the Aleutian megathrust about 90 km long by 115-160 km wide down dip (Johnson and Satake, 1997). The earthquake mechanism is poorly known but most likely involves slip that averages about 7.6 mona gently-dipping (6°) segment of the Aleutian megathrust (Johnson and Satake, 1997).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-16 Appendix 9A Rev. 0, August 23,2002
An alternative interpretation is that a gigantic landslide on the upper continental slope caused both the local and transoceanic tsunamis and may even have been the mechanism of the earthquake (Fryer and Watts, 2001 ). This hypothesis is based on identification of large sea floor topographic features interpreted as one or more landslide scars and a possible mound that is inferred to be a landslide deposit. The near-field tsunami obliterated a reinforced concrete lighthouse and its crew of five Coast Guardsmen at the Scotch Cap Station on the southwestern end ofUnimak Island (Fig. 9). The wave arrived 48 minutes after start of the earthquake, as reported by survivors at the station who were in a communications facility on a bench above the lighthouse. This timing places the source of the wave near the continental shelf break or uppermost slope and above the inner margin of the aftershock zone; from the Coast Guard Station the inferred source is less than half the distance to the main shock epicenter (Fig. 9, inset).
Figure 9 shows new data on tsunami runup heights and movement directions that were obtained along ocean-facing coasts between Unimak Pass on the west and Sanak Island on the east by measuring the height of driftwood deposited by the tsunami (Plafker, Synolakis, and Okal, 2001). Maximum runup is 42.7 mat the Coast Guard Station and is close to 40 m high for about 50 km east of the station. The wave attenuated rapidly east and west of this headland on Unimak Island and maximum runup on seaward-facing shores of Sanak Island was 23m. East ofUnimak and Sanak Islands runup did not reach above the high tide level along the Alaska Peninsula and offshore islands; we have no information on runup heights west ofUnimak Pass. For this event, maximum near-field runup is about 5.5 times larger than the total computed average dip slip (7.6 m) at the tsunami source and it is 11 times larger than the vertical component of displacement at the fault source even for an average megathrust dip as steep as 30°.
The near-field runup data support the concept that the tsunami was generated by one or more large-scale landslides on the upper continental slope south of Unimak Island, although the exact location of the causative slide or slides has yet to be determined. Only a landslide mechanism can account for the wave arrival time at Scotch Cap, run up heights, inferred movement direction of the wave suggestive of a point source, and rapid wave attenuation away from the source. In addition, the slide mechanism is compatible with unconfirmed anecdotal reports by fishermen of local large postquake increases in water depth near the shelf edge.
Neither the near-field wave runup data nor the earthquake mechanism data are adequate to evaluate the relative contributions of tectonic displacements and submarine landslides towards generating the transpacific tsunami.
1994 Java Earthquake The 1994 East Java earthquake (Mw7.8) occurred 250 km south of the east end of Java Island along the inner wall of the Java Trench (Fig. 1 0). Seismic shaking was weakly felt or not felt at all on eastern Java and Bali Islands and it did not cause any damage. The earthquake was followed about 40 minutes after the main shock by a tsunami that severely damaged several villages and killed 223 people (Tsuji and others, 1995).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-17 Appendix 9A Rev. 0, August 23, 2002
Seismologic data indicate that the earthquake ruptured a segment of the Java megathrust 140 km long by 100 km wide with average slip of only about 1 m (Table 4 ). This apparent low slip is derived using an improbably high rigidity of 4 x 1010 Pa. Slip can be increased by a factor of about 4 if appropriate low rigidities are assumed for these very shallow near-trench events (Bilek and Lay, 1999). With an Mw of 7. 8 and Ms of only 7.2, it is another example of a classic "slow" or "tsunamigenic" earthquake (Kanamori, 1972).
Tsunami runup on the south coast of eastern Java Island ranged up to 14m and it was up to 5 m on west Bali Island and the 40 minute travel time was consistent with a source at the earthquake focal region (Fig. 10). On Java and Bali Islands, regional maximum runup is between 3 and 6 m except in a 60 km length of the eastern Java coast where peaks of run up occur between 9 and 14 m high (Tsuji and others, 1995; Synolakis and others, 1995). Attempts to model the tsunami runup, assuming an entirely tectonic origin, have not met with great success (Synolakis and others, 1995). Even with improbably large vertical displacements ( ~ 10 m) at the earthquake source, the models obtain run up of 8.3 to 9.3 m but not the peak run up heights observed. Such large vertical displacements would require dip slip displacements of as much as 20 m even for a fault dip as steep as 30°.
Both the regional and peak run ups for this earthquake have yet to be reconciled with a purely tectonic origin at the source because of the extraordinarily large slip and vertical displacement that would be required. It is of interest that the highest run up recorded occurs near the mouth of a river which suggests the possibility of a local submarine slide-generated wave. However, earthquake-triggered submarine landslides re unlikely considering the weak seismic shaking caused by the earthquake and it is incompatible with the reported wave arrival time at the coast 40 minutes after the main shock.
2001 Southern Peru Earthquake The Peru earthquake (8.4 Mw} on 06/23/01 is of special interest because it has provided some of the most complete seismological and tsunami data for a large and relatively uncomplicated tsunamigenic event along a continental margin arc. Shaking damage killed at least 57 people and destroyed or seriously damaged more than 60,000 homes (US AID 2001) and the associated tsunami resulted in an additional24 dead and missing people (INDEC, 2001).
The earthquake ruptured a segment of the Peru-Chile megathrust 300 km long by 125 km wide (Fig. 11, from Okal and others, in press). Most focal solutions indicate a thrust mechanism with a slight component of left-lateral strike-slip on a gently east-dipping fault plane that strikes roughly parallel to the coast. Average slip on the fault surface is ~2.6 m with a maximum of 4.5 m, centered offshore ~65 km ESE of Camana (Kikuchi and Yamanaka, 2001 ). The earthquake rupture was somewhat slow, but does not exhibit the deficiency in high frequencies characteristic of a truly slow, "tsunami earthquake" (Okal and others, in press).
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-18 Appendix 9A Rev. 0, August 23, 2002
Distribution and maximum height of tsunami run up along the Peru coast, as reported by Okal and others (in press), is shown on Figure 11. The tsunami produced wave heights well above high tide for about 150 km from Atico to Quilca, and damaging waves along the 35 kilometers of coast straddling the Rio Camana. The average run up height is ~5 m and maximum runup height is 7.25 m, excluding a few higher values that record eyewitness reports of heights to which water splashed against the sea cliffs. Maximum runup is approximately 1.5 times the maximum slip inferred from source tomography (Kikuchi and Yamanaka (2001). Both the absolute amplitude of the average maximum run up height and lateral extent of the 2001 tsunami are compatible with the seismologically derived dislocation source (Okal, and others, in press). The narrow peak of run up to 7.25 m off Camana is a few meters too high for the model and may indicate some complication of wave runup due to slumping of the Camana River delta, submarine bathymetry, or some other unknown cause.
RESULTS In this section data for all events in the catalog of larger tsunamigenic earthquakes (Tables 4 and
- 5) since 1943 are summarized and the relevance of these data for forecasting run up for a great tsunamigenic earthquake on the southern Cascadia subduction zone is considered.
Moment Magnitude vs Slip for Tsunamigenic Earthquakes The relevant seismologic and geodetic data in this catalog suggest that as suggested by Geist (1998), average fault slip scales reasonably well with earthquake magnitude with the notable exception of the 1960 Chile for which slip estimates vary widely (Fig. 12). Furthermore tectonic slip for "slow" (or "tsunami") earthquakes is not significantly larger than normal tsunami genic earthquakes of comparable magnitude, assuming constant rigidity as was done for this compilation. "Slow" earthquakes tend to occur along the shallow part of the interplate megathrust near the trench. In this tectonic setting, their slow rupture velocity, relatively low shear wave magnitude, and high average slip have been attributed to a combination of rupture within relatively weak accreted sedimentary rocks and a shallow rupture that intersects the sea floor (Kanamori, 1972; Geist, 1998).
Conditions for generating "slow" earthquakes could be present in the distal part of the Cascadia margin that is underlain by an extensive accretionary prism of Cenozoic age. However, dislocation models based on the configuration of the mega thrust from seismologic data, surface geodetic data, and the distribution of coseismic tectonic subsidence from paleoearthquakes, suggest that slip on the Cascadia megathrust is likely to be deeper and further landward than for a typical "slow" earthquake (Hyndman and Wang, 1993, 1995; Clague, 1997). Thus, the slip versus magnitude relationship in Figure 12 should be applicable for a great Cascadia subduction zone tsunamigenic event.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-19 Appendix 9A Rev. 0, August 23, 2002
Moment Magnitude vs Tsunami Runup Heights Moment magnitude is plotted in Figure 13 against maximum tsunami runup height for the major near-field tsunamigenic earthquakes since 1943; data and sources are given in Table 5. For purposes of discussion, the tsunami genic events are divided into three groups shown by distinctive symbols (Fig. 13).
Events Showing Linear Tectonic Tsunami (Tmax) Runup/Magnitude Trend Group "A" includes 33 events for in which the regional upper limit ofrunup (Tmax) shows a roughly linear relationship with magnitude (Fig. 13). Within this group are seven tsunamigenic earthquakes that occurred in continental margin arcs since 1943 including four of the largest recorded events (1960 Chile, 1964 Alaska, 2001 Peru, and 1979 Columbia). The first three of these events are discussed in more detail in the section on Case Histories.
Earthquakes Having Relatively Large Tsunami Run up Peaks (Tpeak) of Unknown Origin Group "B" includes seven events in which peaks of uncertain origin occur that are larger than maximum regional tsunami runup height (Fig. 13). Two of the five "slow" earthquakes in the catalog are in this group (1994 Java and 1992 Nicaragua), five are "normal" tsunamigenic events. For all of these events the attached blue symbol indicates the maximum runup height based on the general highest levels over long stretches of coast. The red symbols indicate maximum heights of anomalously high run up for the same events the case of which is uncertain.
Except for Hokkaido, the heights of the peak run up is up to 2.25 times higher than the regional run up height. For the Hokkaido event, peak local run up is 4 times that of the regional tsunami maximum height (see Fig. 6 and discussion in the section on Case Histories).
The cause of the relatively high run up above regional levels for these events is uncertain. They may be attributable to peculiarities of wave amplification due to interaction of the tsunami with the sea floor and shoreline, to differential fault slip for near-shore sources, or to earthquake-triggered submarine landslides.
Tsunamis with Relatively Large Tsunami Run up Peaks (Tpeak) of Known or Probable Landslide Origin Group "C" includes five events for which landslide-generated waves occur that are larger than maximum regional tsunami runup height (Fig. 13). Historically, the highest waves associated with non-volcanic tsunamigenic earthquakes have been generated by earthquake-triggered submarine and subaerial landslides. Although waves generated entirely by earthquake-triggered subaerial landslides have produced by far the highest runups (524 m during the 1958 Lituya Bay, Alaska Mw 7.8 earthquake), they are not considered further in this report because they do not constitute a major hazard in coastal Cascadia.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-20 Appendix 9A Rev. 0, August 23, 2002
This group includes five events (shown on Figure 13 and discussed in the section on Case Histories) in which local tsunamis were generated by multiple large near shore earthquake-triggered submarine landslides ( 1964 Alaska, 1992 Flores, and 1994 Mindoro) or by gigantic offshore earthquake-triggered landslides ( 1998 Aitape and 1946 Aleutians). Scores of submarine landslides during the great 1964 Alaska earthquake generated runups generally up to 30 m but locally up to 52 m or 4 times higher than the 12.7 m highest runup generated by tectonic displacement (Fig. 2). The Flores Island earthquake had several high local runup peaks to a maximum height of 26 m that can be directly related to earthquake-triggered slides or suspected slides and more than 3 times estimated regional runup height (Fig. 5). The tsunami associated with the 1994 Mindoro strike-slip earthquake is inferred to be entirely generated by near shore earthquake-triggered landslides (Fig. 7). The destructive tsunami associated with the 1998 Aitape earthquake is interpreted by most workers to be mainly, if not entirely, the result of an enormous earthquake-triggered landslide some 25 km offshore (Fig. 8). New field data for the anomalous 1946 Aleutian event suggest that the near-field tsunami runup to 42 m high was generated by one or more submarine landslides located about 80 km offshore near the edge of the continental shelf (Fig. 9).
Summary Analysis of the well-documented cases oftsunamigenic earthquakes and their associated runups from submarine causes, as shown in Figure 13, leads to some interesting results outlined below.
Tsunamigenic earthquakes can be grouped into three types Group A, B, and C.
o Group "A" has a roughly linear magnitude/run up relationship, the larger the earthquake the larger the run up. Tsunamis in this group are considered to be dominantly of tectonic origin.
o Group "B" are events that have both a tectonic regional tsunami component and local peaks of run up that are larger for a given magnitude than those in Group A.
The cause of these local peaks of run up is uncertain.
o Events in Group C are local run ups that result partly or entirely from submarine landslides. These can be up to 4 times as high as the background measurements of the tectonic component of run ups, and the maximum run up height increases linearly from about 15m to 52 min the magnitude range 7.1 to 9.2, respectively.
There is a roughly linear relationship for typical maximum run ups in Group A from about one meter for magnitude 7.5 earthquakes to 15 meters for magnitude 9 earthquakes.
The maximum tsunami runup is approximately equivalent to both average fault slip and to maximum vertical component of slip for tectonic tsunamis that are not complicated by landslides, unusual bathymetry, or irregular configurations of the coast.
"Slow" tsunamigenic earthquakes occur in all three groups in the magnitude range of7.5 to 8.4.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-21 Appendix 9A Rev. 0, August 23, 2002
Factors that may control the susceptibility of earthquake-triggered submarine landsliding include:
o Submarine slope o Availability of thick sediment accumulation on deltas, glacial margins. and offshore basins o Size and frequency of large earthquakes. Large number of large events may keep the slopes "clean", so only some events cause a significant slides o Occurrence of subsea zones of structural weakness such as shear zones and bedding planes CASCADIA IMPLICATIONS A plausible tectonic model of a subduction zone earthquake for southern Cascadia subduction zone would have a maximum Mw of ~8.5-9.1. Magnitude is based on rupture of the entire Cascadia megathrust with 12m slip, assuming ~4 cm/yr orthogonal convergence rate and 300 years since the previous great subduction zone earthquake (Clague, 1997).
This model is probably conservative because slip is likely to be no more than 8 m in the southern segment of Cascadia due to non-orthogonal convergence, possible loss of elastic strain due to permanent deformation, small earthquakes, and aseismic creep. The vertical component of slip at the sea floor is a major unknown. It would be a function of how coseismic slip is partitioned between the megathrust and splay faults within the upper plate.
Comparison of Model Cascadia event with Historic Tsunamigenic Earthquakes The tectonic setting for Cascadia is similar to other subduction zones at continental margin arcs and very large earthquakes on it are expected to be similar to the 1960 Chile and the 1964 Alaska earthquakes (See Appendix 2A). Therefore, an event for using the Cascadia model is reasonably compatible with the empirical results for historic tsunamigenic events that are not complicated by large submarine slides (Group "A", Fig. 13). For these events, maximum near-field tsunami run up is likely to be in the range of 1 to 1.1 times of the vertical component of fault displacement. For Cascadia, this is about 4 to 6 m.)
Tsunamigenic Submarine Landslides on the Cascadia Margin?
Tsunamis generated by submarine landslides could be generated during major Cascadia earthquakes by massive slides along the lower continental slope and along the steep walls of submarine canyons that cross the continental shelf and slope. The sediment accumulation at the mouths major rivers and the steeping continental slopes from sediment being piled at the front of the subducting slab are the major sources.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-22 Appendix 9A Rev. 0, August 23,2002
Recent Sea Beam bathymetry and multichannel seismic reflection records of the Cascadia continental margin off the Oregon coast have revealed enormous landslide masses with features interpreted as indicative of catastrophic large movement of thousands of square kilometers of the lower continental slope (Goldfinger and others, 2000). Comparable geophysical data are unavailable for the southern Cascadia margin although possible gigantic submarine landslides 5 to 10 km wide and up to 30 km long have been identified at the base of the continental slope on side-scan sonar records Data on rate of slip and age of these landslides is too sparse to determine whether they generated paleotsunami deposits or how much of a hazard they pose for future tsunamis in Cascadia. The limited data available, however, suggest that submarine slide events capable of generating tsunamis on the Cascadia continental slope are rare based on sedimentation rates on the landslide deposits and evaluation of their geomorphic appearance. These slides appear to be tens of thousands to millions of years old compared to the recurrence times for tsunamigenic earthquakes a few hundred to a few thousand years old) in this same region (Goldfinger and others, 2000).
The steep walls of submarine canyons are commonly sites of submarine landslides at all scales and could present a potential hazard in Cascadia. An especially well documented historic case of a destructive non-seismic tsunamigenic slide in a submarine canyon occurred on 1 0/16/79 in the Var River submarine canyon that intersects the Mediterranean Sea coast at Nice, France. A large sediment slump in the canyon, which is estimated to consist of several hundred million cubic meters, generated a tsunami that had a maximum amplitude (from tide gages) of 3m along approximately 12 km of the coast (Seed and others, 1988). The tsunami triggered slumps in shallow water at the Port of Nice, caused loss of several lives, and resulted in considerable property damage. No comparable slides in submarine canyons are known to have accompanied tsunamigenic earthquakes although they undoubtedly have occurred..
In southern Cascadia, the Eel River submarine canyon is probably the only canyon with sufficiently steep topography and high with a high sediment deposition rate to be a possible source of a tsunamigenic slide. High-resolution bathymetric and geophysical data are not available for assessing their probable hazard.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-23 Appendix 9A Rev. 0, August 23, 2002
REFERENCES CITED Abe, K. (1989), Estimate of tsunami heights from magnitudes of earthquake and tsunami: Bull.
Earthquake Res. Inst. Tokyo University, v. 64, 51-59. (Japanese with English abstract).
Abe, Katsuyuki. 1995, Modeling of the runup heights of the Hokkaido-Nansei-Oki tsunami of 12 July 1993: in Tsunamis: 1992-1994, K. Satake and F. Imamura, eds, Pure and Applied Geophysics, v. 144, no. 3/4, p. 735-745.
Abe, Ku., Abe, Ka., Tsuji, Y., Imamura, F., Katao, H., Iio, Y., Satake, K., Bourgeois, J.,
Noguera, E., and Estrada, F. (1993). Field survey of the Nicaragua earthquake and tsunami of September 2, 1992. Bull. Earthq. Res. Inst. 68, 23-70.
Baptista, A.M., Priest, G. R., and Murty, T. S.: 1993, Field survey of the 1992 Nicaragua tsunami, Marine Geodesy 16, 169-203.
Bernard, E., Madher, C., Curtis, G., and Satake, K., 1994, Tsunami inundation model study of Eureka and Crescent City, California: National Oceanic and Atmospheric Administration Technical Memorandum ERL PMEL-1 03, 80 p.
Bilek, Susan, and Lay, Thome, 1999, Rigidity variations with depth along interplate megathrust faults in subduction zones: Nature, v. 400, p. 443-446.
Bourgeois, J., and Reinhart, M.A., 1989, Onshore erosion and deposition by the 1960 tsunami at the Rio Lingue estuary, south-central Chile (abs.): EOS, Transactions of the American Geophysical Union, v. 70, no. 43, p. 1331.
Clague, John, 1997, Evidence for large earthquakes at the Cascadia Subduction Zone: Reviews of Geophysics, v. 35, no. 4, p. 439-460.
Carver, G. A., Abramson, H. A., Garrison-Laney, C. E., and Leroy, T., 1998, Investigation of paleotsunami evidence along the north coast of California: Final Report for Pacific Gas and Electric Company, 164 p. plus appendices.
Carver, D. H., and Carver, G. A., 1996, Earthquake and thunder-native oral histories of paleoseismicity along the southern Cascadia subduction zone (abs): Geological Society of America, Cordilleran Section, Abstracts with Program, Annual Meeting, v.28, no. 5, p. 54.
Davies and others, 2001 Coulter, H.W., and Migliaccio, R.R., 1966, Effects of the earthquake of March 27, 1964, at Valdez, Alaska: U.S. Geological Survey Professional Paper 542-C, 36 p.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-24 Appendix 9A Rev. 0, August 23, 2002
Fryer, G.J., and Watts, Philip, 2001, Motion of the Uganik Slide, probable source ofthe tsunami of 1 April1946: ITS 2001 Proceedings, session 6, no. 6-6, p. 683-694.
Furumoto, A. S. (1991). Source parameters of destructive tsunamis: Science of Tsunami Hazards, no. 9, p.95-113.
Geist, E.L., 1998, Local tsunamis and earthquake source parameters: Advances in Geophysics, v.
39, p. 117-209.
Geist, E. L., 1998, Source characteristics of the July 17, 1998 Papua New Guinea tsunami: EOS, Transactions of the American Geophysical Union, v. 79 (supplement), p. 571.
Goldfinger, Chris, and Watts, Philip, 2001, Tsunamigenic mega-slides on the southern Oregon Cascadia margin: ITS 2001 Proceedings, session 3, no. 3-3, p. 501.
Hatori, T., 1968, Study on distant tsunamis along the coast of Japan; Pt. 2, Tsunamis of South American origin: Tokyo University Earthquake Research Institute Bulletin, v. 46, p. 345-359.
Herd, D.G., Youd, T.L., Hansjurgen, Meyer, Arango C., G.L., Person, W.J., and Mendoza, Carlos, 1981, The great Tumaco, Colombia earthquake of 12 December 1979: Science, v. 211, p.
441445.
Hidayat, D., Barker, J.S., and Satake, K., 1995, Modeling the seismic source and tsunami generation ofthe December 12, 1992 Flores Island, Indonesia, earthquake: in Tsunamis:
1992-1994, K. Satake and F. Imamura, eds., Pure and Applied Geophysics, v. 144, no. 3/4, p.
537-568.
Hokkaido-Nanseki-Oki earthquake reconnaissance team, 1995, Hokkaido Earthquake Reconnaissance Report: Earthquake Spectra, R.M. Chung, ed., Pub. 95-01, 166 p.
Hurukawa, N., Tsuji, Y., and Waluyo, B., in press, The Papua, New Guinea earthquake and its fault plane estimated from relocated aftershocks: ITS 2001 Proceedings, session 2, no. 2-3, p.. @
Hyndman, R.D., and Wang, K., 1993, Tectonic constraints on the zone of major thrust earthquake failure: The Cascadia subduction zone: Journal of Geophysical Research, v. 98, p.
2039-2060.
Hyndman, R.D., and Wang, K., 1995, The rupture zone of Cascadia great earthquakes from current deformation and the thermal regime: Journal of Geophysical Research, v. 100, p.
22,133-22,154.
Imamura, F., Gica, E., Takahashi, To., and Shuto, N. (1995). Numerical simulation of the 1992 Flores tsunami: interpretation of tsunami phenomena in northeastern Flores Island and damage at Babi Island. Pure and Applied Geophysics, v. 144, p. 555-568.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-25 Appendix 9A Rev. 0, August 23, 2002
Imamura, Fumihiko, Synalokis, C.E., Gica, Edison, Titov, Vasily, Listanco, Eddie, and Lee, H.J., 1995, Field survey of the 1994 Mindoro Island, Philippines tsunami: in Tsunamis:
1992-1994, K. Satake and F. Imamura, eds., Pure and Applied Geophysics, v. 144, no. 3/4, p.
875-890.
INDEC (2001). Resumen final de dafios en distritos afectados por el sismo del23-06-01 Y sub-siguintes ocurridos en el sur del pais, Instituto Nacional de Defensa Civil, Lima, Peru, http://www.indeci.gob.pe/resumdist27nov08h.htm Johnson, J.M. and Satake, Kenji, 1997, Estimation of seismic moment and slip distribution of the April 1, 1946, Aleutian tsunami earthquake: Journal of Geophysical Research, v. 102, p.
11,765-11,774.
Kachadoorian, Reuben, 1965, Effects ofthe earthquake of March 27, 1964, at Whittier, Alaska:
U.S. Geological Survey Professional Paper 542-B, 21 p.
Kanamori, Hiroo, and Kikuchi, Masayuki, 1972, The 1992 Nicaragua earthquake: a slow tsunami earthquake associated with subducted sediments: Nature, v. 361, p. 714-716.
Kikuchi, M., andY. Yamanaka (2001). EIC Seismological note Number 105, http:/ /wwweic.eri.u-tokyo.ac.jp/EIC/EIC _ news/1 05E.html.
Koshimura, S., and V. Titov (2001). Preliminary model results for the 23 June 2001 Peruvian tsunami, Proceedings of the International Tsunami Symposium 2001 (ITS 2001) (on CD-ROM),
Pacific Marine Environmental Laboratory, NOAA, Session 2, No. 2-2, 379.
Lemke R.W., 1966, Effects of the earthquake of March 27, 1964, at Seward, Alaska: U.S.
Geological Survey Professional Paper 542-E, 43 p.
Lockridge, 1985 McCulloch, D.S., 1966, Slide-induced waves, seiching, and ground fractures caused by the earthquake of March 27, 1964, at Kenai Lake, Alaska: U.S. Geological Survey Professional Paper 543-A, 41 p.
Myers, E.P., Baptista, A.M., and Priest, G.R., 1999, Finite element modeling of potential Cascadia subduction zone tsunamis: Science of Tsunami Hazards, 17, (1 ), 3-18.
Pelinovsky, Efim, Yuliadi, Dede, Prasetya, Gegar, and Hidayat, Rahman, 1997, The January 1, 1996 Sulawesi, Island tsunami: Tsunami Hazards, v. 15, no. 2, p. 107-120.
PHIVOLCS Quick Response Team, 1994, Philippine Institute of Volcanology and Seismology Special Report No. 2, 11 p.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-26 Appendix 9A Rev. 0, August 23, 2002
Plafker, George, 1997, Catastrophic tsunami generated by submarine slides and backarc thrusting during the 1992 Flores Island, Indonesia earthquake [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p.
Plafker, George, and Kachadoorian, Reuben, 1966, Geologic effects of the March 1964 earthquake and associated seismic sea waves on Kodiak and nearby islands, Alaska: U.S.
Geological Survey Professional Paper 543-D, 46 p.
Plafker, George, 1969, Tectonics of the March 27, 1964, Alaska Earthquake: U.S. Geological Survey Professional Paper 543-I, 74 p.
Plafker, George, Kachadoorian, Reuben, Eckel, E.B., and Mayo, L.R., 1969, Effects of the earthquake of March 27, 1964, on various communities: U.S. Geological Survey Professional Paper 542-G, 50 p.
Plafker, George, 1972, The Alaskan earthquake of 1964 and Chilean earthquake of 1960; Implications for arc tectonics: Journal of Geophysical Research, v. 77, no. 5, p. 901-925.
Plafker, George, and Savage, J.C., 1970, Mechanism of the Chilean earthquakes of May 21-22, 1960: Geological Society of America Bulletin, v. 81, p. 1001-1030.
Plafker, George and Ward, S.N., 1992, Backarc thrust faulting and tectonic uplift along the Caribbean Sea coast during the April22, 1991 Costa Rica earthquake: Tectonics, v. 11, no. 4, p.
709-718.
Plafker, George, 1997, Catastrophic tsunami generated by submarine slides and backarc thrusting during the 1992 Flores Island, Indonesia earthquake [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p.
Richter, C.F., 1958, Elementary seismology: W.H. Freeman & Company, Inc., 768 p.
Satake, K., and Imamura, F., 1995, Introduction to Tsunamis: in Tsunamis: 1992-1994, K.
Satake and F. Imamura, eds., Pure and Applied Geophysics, v. 144, no. 3/4, p. 373-380.
Satake, K., and Tanioka, Y., 1999, The July 1998 Papua New Guinea earthquake and tsunami: a generation model consistent with various observations [abstract]: EOS, v. 80, F750-F751.
Seed, H.B., and Rahman, M.S., 2001, Wave-induced pore pressure in relation to ocean floor stability of cohesionless soils. Marine Geotechnology, v. 3, p. 123-150.
Shepard, F.P., MacDonald, G.A., and Cox, D.C., 1950, The tsunami of April1, 1946: Bull.
Scripps Inst. Oceanography, Univ. California, no. 5, p. 1956-1962.
Sievers C., H.A., Villegas C., Guillermo, and Barros, Guillermo, 1963, The seismic sea wave of 22 May 1960 along the Chilean coast: Bulletin of the Seismological Society of America, v. 53, no. 6, p. 1125-1190.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-27 Appendix 9A Rev. 0, August 23, 2002
Synolakis, C.E., J.-P. Bardet, J.C. Borrero, H.L. Davies, E.A. Okal, E.A. Silver, S. Sweet, and D.R. Tappin (2002). The slump origin of the 1998 Papua New Guinea tsunami, Proc. Roy. Soc.
(London), Ser. A, 458, 763-789.
Tappin, D.R., Watts, Philip, McMurty, G.M., and Matsumoto, Takeshi, 2001, Offshore evidence on the source of the 1998 Papua New Guinea tsunami: A sediment slump: ITS 2001 Proceedings, session 2, no. 2-3, p. 381-388.
Tsuji, Y., and Matsutomi, H., 1993, Damages due to the tsunami: Report of the field survey on the Flores Island earthquake-tsunami of December 12, 1992: Rep. Grant in aid no. B-4-4, p.
70-87.
Tsuji, Y., Imamura, F., Matsutomi, H., Synolakis, C. E., Nanang, P. T., Jumadi, S., Harada, S.,
Han, S.S., Arai, K., and Cook, B., 1995, Field survey of the east Java earthquake and tsunami of June 3, 1994: in Tsunamis: 1992-1994, K. Satake and F. Imamura, eds., Pure and Applied Geophysics, v. 144, no. 3/4, p. 839-854.
USAID (2001), Peru Earthquake Fact Sheet #6 (FY 2001), U.S. Agency for International Development, ReliefW eb http:/ /www.reliefweb/int.
Watanabe, H., 1985, Catalog of hazardous tsunamis in Japan: University of Tokyo Press, Tokyo, 206 p.
Wells, D.L. and Porrazzo, V.F., 1994, The 15 November 1994 M 7.I mindoro Island earthquake in the Phillipines: unpublished report to EERI, 12/15/94).
Yamashita, T. (1976). On the dynamical process of fault motion in the presence of friction and inhomogeneous initial stress, Part I. Rupture propagation. Journal of the Physics of the Earth, v.
24, p. 417-444.
Yeh, Harry, Imamura, Fumihiko, Synalokis, Costas, Tsuji, Yoshinobu, Liu, Philip, and Shi, Shaozhong, 1993, The Flores Island tsunamis: EOS, Transactions, American Geophysical Union,
- v. 74, no. 33,p. 369-373.
Yeh, Harry, Titov, Vasily, Gusiakov, Viacheslav, Pelinovsky, Efim, Khramushin, Vasily, and Kaistrenko, Victor, 1995, The 1994 Shikotan earthquake and tsunami: in Tsunamis: 1992-1994, K. Satake and F. Imamura, eds, Pure and Applied Geophysics, v. 144, no. 3/4, p. 855-874.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 9A-28 Appendix 9A Rev. 0, August 23, 2002
Table 1. May 21, 1960 Chile earthquake (Mw = 9.5) near-field tsunami data and coseismic vertical displacements. [Tsunami data from Sievers and others, 1963; coseismic displacements from Plafker and Savage, 1970; Table 4]
No.
(Fig. 3) 2 3
4 5
6 7
8 9
10 11 12 rJ Maximum Location run up height (m)
Aysen 1.0 Puerto 3.0 Aguirre Melinka
?
Isla Guafo 10.0 A chao 2.5 Puerto Montt 0
An cud 5-6 Gulf of 1.5 Quetalmahue Playa 15-20 Chauman Maull in 14 Caleta Mansa 12 Puerto de 8.5-10 Corral Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Coseismic displacement (m) 0?
0.0 to+ 1.0
-1.1 to -1.3
+3.6
-0.9 0.0 to +Yz
-1.3
-1.5 to -1.8
-1.0 to -1.5
-1.6 to -1.7
-1.3 to -1.6
-2.1 Comments 3 waves reported First wave arrived 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 10 minutes after the earthquake; second wave 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 20 minutes later. Wave height estimated Lighthouse keepers report 3 waves and wave damage, but no wave heights Sea withdrawal began about 1 0 minutes after earthquake and was soon followed by first wave from the west. 4 waves reported 3 waves reported; highest wave reached to high tide line; no damage No tsunami observed First wave about 20 minutes after earthquake; large wave struck 50 1ninutes after earthquake. 4 waves reported; initial rise approximately 1 m First wave seen offshore 18-20 minutes after earthquake about 800 m off coast; wave height estimated by lighthouse keeper (height estimate not included on Figure 1)
First wave arrival about 20 minutes after earthquake followed by withdrawal. 8 waves reported; 2d and 4th waves highest First wave 15 minutes after earthquake. 3 waves reported; 3d wave highest. Wave height corrected for tide stage First wave crest about 40 minutes after earthquake was preceded by withdrawal. At least 3 waves; 2d and 3d highest 9A-29 Appendix 9A Rev. 0, August 23, 2002
No.
(Fig. 3) 13 14 15 16 17 18 Ia Location Caleta Mehuin Caleta Queule Puerto Saavedra Isla Mocha Lebu Lota Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 8.5 4+
7-8 15 3-4 1.5
-1.6
-2.0
-1.2 to -1.6
+ 0.9 to +1.8
+0.9 to +1.0 0.0 Table 1 (Continued)
Comments Rapid initial withdrawal of water followed by rapid rise beginning about 15-20 minutes after earthquake. 3 waves reported; 3d wave highest Heavy damage First wave followed withdrawal beginning about 25-30 minutes after earthquake. 3 waves reported; 3d wave highest 3 waves reported; 1st wave highest and preceded by withdrawal beginning about 1 0 minutes after earthquake 3 waves reported First wave at about 50 minutes after earthquake followed withdrawal. 5 waves reported 9A-30 Appendix 9A Rev. 0, August 23,2002
Table 2. March 27, 1964 Alaska earthquake (Mw = 9.2) near-field tsunami data and coseismic vertical displacements.
[After Lemke, 1967; Plafker, 1969; Plafker and Kachadoorian, 1966, fig. 18; Plafker, and others, 1969]
No.
1 2
3 4
5 6
7 8
9 10 11
!I
- Maximum Location run up height (m)
Sitkinak Island 0
Kaguyak 5.2+
Sitkalidak 7.5 Island Port Hobron 4.3+
Old Harbor 3.7 Shearwater 4.4 Bay UgakBay 6.1+/-0.6 (Pasagshak Bay)
Sacramento 12.7 River Myrtle Creek 5.7 Cape Chiniak 12.2 Womens Bay 3.9 Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Coseismic displacement Comments (m)
KODIAK ISLANDS REGION
+0.3
-0.6
+0.2
-0.9
-0.8
-0.9
-0.9
-0.6
-1.5
-1.2
-1.6 1st wave arrived 3 8+/-5 minutes after start of earthquake 1st wave arrived 48 tninutes after start of earthquake. 3d wave between 8:30 and 9:30P.M. highest and most destructive.
1st wave arrived at Saltery Cove, U gak Bay, about 30 minutes after start of earthquake Assumes measured run up was for 1st wave 6 waves recorded on streamflow gage about 1,600 m above stream mouth. 1st wave arrived 70 minutes after start of earthquake 1st wave arrived 38 minutes after start of earthquake. Height assumes measured run up was for 1st wave 10 waves reported. 1st wave crest at 6:35P.M. 63 minutes after start of earthquake; 2d wave at about 7:40 P.M.was highest and most destructive 9A-31 Appendix 9A Rev. 0, August 23, 2002
No.
12 13 14 15 16 17 18 19 20 21 22 23
!I Location Afognak Kitoi Bay Cape Current Port William Terror River U ganik River UyakBay Karluk Rocky Bay Seward Whidbey Bay Puget Bay
- Maximum run up height(ni)
~ ~
..).
..)
2.7+
3.7+
1.5+
2.8 1.9 1.3 0.5 2.7 9-12 12.2 8.5 Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 Coseismic
. displacement (m)
Table 2, continued Comments KODIAK ISLANDS REGION
-1.4
-1.7
-1.3
-1.2
-1.2
-1.0
-0.6
-0.3 3d wave between 8:30 and 9:30P.M. highest and most destructive 5 waves reported on streamflow gage 1,127 m above stream mouth. Probably includes seiche waves 3 waves recorded on streamflow gage 800 m above stream mouth KENAI PENINSULA
-1.5 1st wave arrived approximately 30 minutes after start of earthquake (run up about 2.7 m). Highest and most damaging wave at midnight near high tide (runup about 1.5 m above tide level)
-1.1 1st wave arrived about 28-29 minutes after start of earthquake. 3d wave probably highest
+0.45 to 0.6 1st wave arrived 1912 minutes after start of earthquake (runup about 10.7 m).
2d wave at about 30-32 minutes after start of earthquake was highest
+ 1.5 1st wave arrived about 20 minutes after start of earthquake (run up about 5.5 m). 3d wave at about 212 hours0.00245 days <br />0.0589 hours <br />3.505291e-4 weeks <br />8.0666e-5 months <br /> after start of earthquake was highest and most destructive 9A-32 Appendix 9A Rev.O,August23,2002
No.
24 25 26 27 28 Location Phipps Point Hook Point Cordova Cape St. Elias Cape Yakataga Maximum run up height (m) 8.5 10.7 4.8 Coseismic displacement (m)
Table 2 (Continued)
Comments PRINCE WILLIAM SOUND
+1.8
+1.8
+1.9 Highest and most damaging wave, which almost coincided with high tide at 12:30 A.M. on 3/28/94, was 4.8 m above tide level ISLANDS & MAINLAND COAST EAST OF PRINCE WILLIAM SOUND
+2.4 3.0 0.0 1st wave arrived from southeast about 39 minutes after start of earthquake.
Immediately followed by 2d wave which was the highest wave 8 waves reported
- Corrected for stage of tide where known; "+" sign after numeral indicates uncorrected value m
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 9A-33 Appendix 9A Rev. 0, August 23,2002
rJ Table 3. April 22, 1991 Limon, Costa Rica earthquake (Ms =7.5) tsunami data and coseismic vertical displacements [From Plafker and Ward, 1992].
No.
Location (Lat./Long).
10°02' 18"N./83 °07' 54"W.
2 10°00' 16"N./83°05'55"W 3
09°56'59"N./83°00'57"W 4
09°54'06"N./82°58' 42"W 5
09°43'15"N./82°49'00"W 6
09°39'29"N./82°45'31"W 7
09°38'42"N./82°41' 12"W 8
09°38'06"N./82°39'33"W 9
09°38' 15"N./82°39' 15"W 10 09°35'55"N./82°36'24"W Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Maximum runup height (m) 1.35 0.65 to 0.71 1.30+
0.65 to 1.70 1.16 1.55 2.00+
1.30 0.83 1.25+
Coseismic displacement (m) 0
+1.27
+0.74
+0.52 0.73
+0.38
+0.40 to +0.45
+0.30
+0.40
+0.30 to +0.40 9A-34 Comments 1st wave arrival 5 minutes after start of earthquake 1st wave arrival 3 to 5 minutes after start of earthquake 1st wave arrival 1 0 minutes after start of earthquake 1st wave arrival 5 minutes after start of earthquake Appendix 9A Rev. 0, August 23, 2002
Table 4. Selected source parameters for post-1943 tsunamigenic earthquakes for which runup ~ 2 m. Tsunami runup data associated with these events are given on Table 5.
No.
2 3
4 5
6 7
s 9
10
!I Date Region
(*slow eq.)
05/22/60 Chile (Fig. 1) 03/2S/64 Alaska (Fig. 2) 02/04/65 Rat Islands 03/09/57 Aleutian 06/23/2001
- S. Peru (Fig. 11) 10/04/94 Shikotan 12/12/79 Colombia 12/20/46 Nankaido 05/16/6S Tokachi-Oki 02/17/96 Irian Jaya Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Mo (1020Nm) 2000.
630 630.
140.
ss.
- 47.
- 30.
- 29.
- 39.
2S.
- 24.
Mw 9.5 9.2 S.7 S.6 S.4 S.3 S.3 S.2 S.2 S.2 a Average Maximum Slip (m)
Slip (m) 24 20.3 54 sb 41b S.6 1S
~12.1 20+/-5b
~9.7 12.0
~1.3 7.0
~2.6 4.5
~4.3
~3.2 5.S
~1.5 2.4
~4.7
~3.4 9A-35 Length Width (km)
(km) 920 300 900 150 500 300 650 200 600 60 1100 150 300 125
~220
~so 230 100 360 1SO 150 100
~1SO
~so References Kanamori and Cipar ( 197 4 );
Kanamori ( 1977)
Linde and Silver (19S9)
Barrientos and Ward (1990)
Johnson and others (1996)
Plafker (1969);
Beck and Christensen ( 1991)
Johnson and Satake (1993)
Okal and others (in prep.); Mw and Mo from Harvard CMT Yeh and others (1995). Mw and Mo from Harvard CMT Beck and Ruff(19S4)
Satake (1993)
Kanamori (1971); Mw from Abe (1995)
Imamura and others (1997); Mw and Mo from Harvard CMT Appendix 9A Rev. 0, August 23, 2002
Table 4 (Continued)
No.
Date Region Mo Mw a Average Maximum*
Length Width References
(*slow eq.)
(1020Nm)
Slip (m)
Slip (m)
(km)
(km) 11 04/01/46
- Aleutian
- 23.
8.2
-7.6 95 80 Johnson and Satake (1997)
(Fig. 9) 12 08/01/69 Kurile
- 22.
8.2
-3.6 180 85 Abe (1973) 13 12/07/44 Tonankai
- 20.
8.2
-0.8 1.6 270 180 Sa take (1993) 14 08/16/76 Mindanao
- 19.
8.1
-3.7 160 80 Stewat1 and Cohn ( 1979 15 03/04/52 Tokachi-Oki
- 17.
8.1
-9.4 90 50 Hatori (1966); Mw and Mo from Kanamori (1972) 16 07/30/95 Chile 14.2 8.1
-2 3.5 195 90 Delouis and others (1997) 17 03/03/85 Chile
- 15.
8.0
-1.6 2.9 200 120 Mendoza and others ( 1994) 18 10/09/95 Mexico 14.2 8.0
-2.1 3.5 185 90 Zobin ( 1997) 19 01/01/96 Sulawesi 7.8 7.9
-7.5 65 40 Pelinovsky and others (1997); Mw and Mo from Harvard CMT 20 06/17/73 Nemuro-Oki 6.7 7.8
-2.8 100 60 Shimazaki (1974) 21 10/13/63
- Kurile
- 6.
7.8
-3 110 45 Beck and Ruff(1987); Mw from Pelayo and Wiens (1992) 22 06/02/94
- Java 5.34 7.8
-1 140 100 Tsuji and others (1995); Mw and Mo (Fig. 10) from Harvard CMT 23 12/12/92 1992 Flores I.
5.1 7.7
-3.2 100 40 Back arc thrust. Y eh and others (Fig. 5)
(1993); Mw and Mo from Harvard CMT Ia Humboldt Bay ISFSI Project Technical Report 9A-36 Appendix 9A TR-HBIP-2002-01 Rev. 0, August 23, 2002
No.
24 25 26 27 28 29 30 31 32 33 m
Date Region
(*slow eq.)
07/12/93 Hokkaido (Fig. 6) 05/26/83 Akita-Oki 06/16/64 Niigata 09/02/92
- Nicaragua (Fig.4) 04/22/91 Costa Rica (Fig. 3) 09/21185 Mexico 02/21196 N. Peru 06/10/75
- Kurile 04/01/68 Miyazaki-Oki 02/01/74 Solomon Is.
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Mo Mw (1020Nm) 4.6 7.7 4.55 7.7 7.6 3.4 7.6 3.3 7.6 2.5 7.5 2.2 7.5
- 2.
7.5 1.8 7.4 1.4 7.4 Table 4 (Continued) a Average Maximum Length Slip(m)
Slip (m)
(km)
~2.6 6.0 150
~3.2 7.6 120 b~6 10
~90
~1.1 160
~2.2 75
~1.3 2.00 70
~1.3 110
~0.8 100
~2.5 56
~1.2 40 9A-37 Width (km) 30 30
~40 50 50 70 40 60 32 75 References Back arc thrust. Hokkaido-Nanseki-Oki earthquake Reconnaisance Team (1995); Mw and Mo from Harvard CMT Fukuyama and Irikura (1986); Mw and Mo from Harvard CMT Nakamura and others (1964); Hatori (1965);
Kikuchi and Kanamori (1995); 1998);
Mw and Mo from Harvard CMT Back are thrust. Plafker and Ward (1992); Mw and Mo from Harvard CMT Mendoza (1995); Mw and Mo from Harvard CMT Ihmle and others (1996); Mw and Mo from Harvard CMT Pelayo and Wiens (1992)
Shono and others (1976)
Lay and Kanamori (1980)
Appendix 9A Rev. 0, August 23, 2002
No.
Date Region
(*slow eq.)
34 01/01/94 Mindoro I.
(Fig. 7) 35 07/17/98 Aitape (PNG)
(Fig. 8) a Calculated assuming Jl = 4x1010 Pa b From onshore surface deformation II Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 Mo Mw (1020Nm) 7.1 7.0 Table 4 (Continued) a Average Maximum Slip(m)
Slip (m) b3.4 1-2 9A-38 Length Width (km)
(km)
~30
~40
~15 References PHIVOLCS (1994). Mechanism is dominantly dextral strike-slip on a steeply-dipping N-S fault.
Geist (200 ); NOAA website.
Mechanism probably dip-slip on a steeply dipping offshore E-W trending fault. Earthquake triggered a large submarine landslide Appendix 9A Rev. 0, August 23, 2002
Table 5. Large tsunami genic earthquakes and near-source tsunami run up, 1943-2001. Tmax is the regional upper limit of run up caused by tectonic deformation or very large landslides. Tpeak refers to local peaks ofrunup 0.75 2 times Tmax that may be generated by landslides or by amplification of the tectonic tsunami due to bathymetry, shoreline configuration, or wave reinforcement.
Earthquake source data for these events are given on Table 1.
No.
2 3
4 5
6 7
8 9
m Date Region
(*slow eq.)
05/22/60 Chile (Fig. 1) 03/28/64 Alaska (Fig. 2) 02/04/65 Rat Island 03/09/57 Aleutian 06/23/2001
- S. Peru (Fig. 11) 10/04/94 Shikotan 12/12/79 Colombia 12/20/46 Nankaido 05/16/68 Tokachi-Oki Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 Mw Tmax (m) 9.5 15.0 9.2 5--12.7 8.7 10.7 8.6 15 8.4 5
8.3 5-7 8.3 3.8 8.2
~4 8.2 3.5 Tpeak (m) 52 7
10.0 4.8 Tsunami Comments Data Sources Sievers and others (1963)
First tsunami waves reached outer coast 15-59 minutes after start of earthquake with measured regional run up of 10 to 15 m along 600 km of the coast.
Lemke, 1967; Plafker (1969); Tectonic tsunami struck 19~+/-~ minutes after start of Plafker and Kachadoorian (1966); Plafker and others (1969); McCulloch (1966)
Stover and Coffman ( 1993)
Stover and Coffman (1993)
Okal and others (200 1)
Yeh and others (1995)
Herd and others (1981)
Abe, (K.), (1989)
Abe, (K.), (1989) 9A-39 earthquake; Tmax 7.5 to 12.7 m along 550 km of coast.
Scores of highly destructive landslide-generated waves in fiords and lakes with Tpeak 20--52 m 10.7 m on Shemya I; flooding at Amchitka I. No other local runup data available 15m runup at Scotch Cap, Unimak 1.; 8 mat Sand Bay, Great Sitkin I. No other local runup data available Inundation along ~300 km of coast First wave arrival 10-15 minutes after start of earthquake.
1.5 m coseismic subsidence at site of highest run up Appendix 9A Rev. 0, August 23, 2002
No.
10 11 12 13 14 15 16 17 18 19 20 21 rJ Date Region
(*slow eq.)
02/17/96 Irian Jaya 04/01/46
- Aleutian (Fig. 9) 08/01/69 Kurile 12/07/44 Tonankai 08/16/76 Mindanao.
03/04/52 Tokachi-Oki 07/30/95 Chile 03/03/85 Chile 10/09/95 Mexico 01/01/96 Sulawesi 06/17/73 Nemuro-Oki 10/13/63
- Kurile Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 Mw 8.2 8.2 8.2 8.2 8.0 8.1 8.1 8.0 8.0 7.9 7.8 7.8 Tmax Tpeak (m)
(m) 4.5 7.7
~42 4.5 5.9 5.0 5.0 4.0 2.8 2.4 3.5 3.5 5
3.4 4.5 4.2 4.4 Table 5 (Continued)
Tsunami Data Sources Comments Imamura and others (1997)
Peak runup, located on opposite side ofBiak Island from the tectonic tsunami source inferred to be generated by a near-shore submarine landslide Shepard and others (1950);
Fryer and Watts (200 1 );
Plafker and others (200 1 ),
Okal and others (in prep)
Lockridge and Smith (1984)
Abe, (K.), (1989)
ITIC Newsletter Abe, (K.), (1989)
Ramirez and others ( 1997)
Lockridge (1985)
ITIC Newsletter Pelinovsky and others ( 1997)
Abe, (K.), (1989)
Iida and others (1967) 9A-40 First and highest tsunami, with 42 m runup at Scotch Cap, was probably landslide-generated. A major transoceanic tsunami of uncertain origin caused damage and deaths in Hawaii and elsewhere in the south Pacific Ocean Appendix 9A Rev. 0, August 23, 2002
No.
22 23 24 25 26 27 Date Region
(*slow eq.)
06/02/94
- Java (Fig. 10) 12/12/92 1992 Flores I (Fig. 5) 07/12/93 Hokkaido (Fig. 6) 05/26/83 Akita-Oki 06/16/64 Niigata 09/02/92
- Nicaragua (Fig.4)
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-01 Mw 7.8 7.7 7.7 7.7 7.6 7.6 Tmax Tpeak (m)
(m) 3-6 13.9
~5 26 8
32 4.0 7.5 6.4 6
10.0 Table 5 (Continued)
Tsunami Data Sources Tsuji and others (1995)
Yeh and others (1993); Tsuji and Matsutomi (1993); Tsuji and others (1995); Hidayat, Barker, and Satake (1995);
Imamura and others (1995);
Plafker (1997)
Hokkaido-N anseki-Oki Earthquake Reconnaisance Team (1995); Abe, (K.),
(1989)
Abe, (K.), (1989)
Abe, (K.), (1989)
Abe, (Ku) and others (1993);
Baptista and others ( 1993) 9A-41 Comments First wave arrival 40 minutes after start of earthquake.
Regional inundation of ~300 km of coast 3 to 6 m with local peaks of9 to 13.9 m.
Tmax ~ 5 m in western part of source region. Numerous subaerial and submarine landslides. Probable and known landslide-generated waves in the Babi Island area and eastern Flores Island had peaks of 11-26 m. First Tpeak waves struck coast in less than 3 minutes from start of earthquake First waves arrived 3-5 minutes after start of earthquake at Okushiri Island with Tmax of 5-15 m. Three local peaks of 20-32 m near the southern tip of the island. Tmax on Hokkaido Island ~5 m with local peaks up to ~9.5 m.
Appendix 9A Rev. 0, August 23, 2002
No.
28 29 30 31 32 33 34 35 rJ Date Region
(*sloweq.)
04/22/91 Costa Rica (Fig. 3) 09/21/85 Mexico 02/21/96
- N. Peru 06/10/75
- Kurile 04/01/68 Miyazaki-Oki 02/01/74 Solomon Is.
01/01194 Mindoro I.
(Fig. 7) 07/17/98
- Aitape (PNG)
(Fig. 8)
Humboldt Bay ISFSI Project Technical Report TR-HBIP-2002-0 1 Mw 7.6 7.5 7.5 7.5 7.4 7.4 7.1 7.1 Tmax Tpeak (m)
(m) 2.0 1.9 2.5 5
4.0 5.9 4.5 6.8 3.4 4.5 7.3 15 Table 5 (Continued)
Tsunami Data Sources Plafker and Ward (1992)
Farreras and Sanchez (1991)
Bourgeois and others (1999)
Pelayo and Wiens (1992)
Abe, (K.), (1989)
Geist (1998)
Imamura, and others (1995)
Int. Tsunami Survey Team (1998); Tappin and others (200 1 ); Davies and others (2001) 9A-42 Comments Back arc thrust fault source. First wave arrivals 3-10 minutes after start of earthquake.
Runup 2-5 m from go to 10° S.
Numerous subaerial landslides. Waves struck coast 2-5 minutes after the earthquake in areas of large deltas and steep topography. Data suggest probable multiple slide sources for the tsunami Waves arrived 10-25 minutes after the earthquake. Most likely main tsunami source is a gigantic submarine slide ~5 x 5 km in area that has been identified on the continental slope by marine geophysical surveys Appendix 9A Rev. 0, August 23, 2002