ML19331C233

Draft Site Dependent Response Spectra

ML19331C233
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Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	07/31/1980
From:	WESTON GEOPHYSICAL CORP.
To:
Shared Package
ML19331C227	List: B10051, Forwards Addl Info Re Scope & Status of Seismic re-evaluation Program Including Summary of Program,Update of Criteria Document & Weston Geophysical Corp Draft Site Dependent Response Spectra ML19331C233
References
TASK-02-04.A, TASK-02-04.B, TASK-02-04.C, TASK-03-06, TASK-3-6, TASK-RR NUDOCS 8008140417
Download: ML19331C233 (70)

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SITE DEPENDENT RESPONSE SPECTRA HADDAM NECK SITE DRAFT BEPORT prepared for

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NORTHEAST UTILITIES SERVICE COMPANY

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l July 1980

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l Q) sical

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Weston GeophyCORPORATION 8008140N)h

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TABLE OF CONTENTS Pace l.0 INTRODUCTION 1

2.0 THE SIE DEPENDENT RESPONSE

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SPECTRA METHODOIDGY 6

3.0 EVALUATION OF TE GROUND MOTION POTENTIAL AT TE HADDAM NECK SITE

'7 3.1 Introduction 7

3.2 Regional Tectonic Fra=ework 8

3.2.1 Pied =ont Atlantic Coastal Gravity Province - Site Province 9

3.2.2 Southeastern New England Platfor=

11 3.2.3

• destern New England Fold Belt Province 13

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3.2.4 Northeastern Massachusetts Thrust Fault Complex 15 3.3 Esticated Seismic Intensities at the Haddas l

Neck Site 16 4_

3.4 Reco==endations for Magnitude and Distance of Design Earthquake 18 3.5 Haddas Neck Site Characteristics 22 4.0 DERIVATION OF RESPONSE SPECTRA 23 4.1 Strong Motion Data Rase 23 4.1.1 Data Base Search 24 4.2 Data Processing 26 4.2.1 Strong-Motion Signal Correction 26 4.2.2 Spectra Derivation 28 i

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i TA!3LE OF CONTENTS (CONT'D.)

Page

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4.3 Results

Seismic Response Spectra 29

5.0 CONCLUSION

34 REFERE NCES TABLES FIGURES

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APPENDIX A EARTIIQUAKE CATALOG ii Weston Geophysical

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DRAFT l.0 INTRODUCTION Seismic design values for nuclear power plants are based on two basic decisions:

first, the selection of the size and location of an earthquake which represents a con-servative assessment of the source of maximum vibratory motion at the site; second, a conservative assessment of i

j the resulting ground motion at the site, considering the effects of the local geologic conditions.

The second as-sessment is generally provided in terms of a frequency-l

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dependent response spectrum.

Using'seisric and geologic data, recent investigators (Aki, 1979; Bouchon, 1979, 1980a, b) have successfully computed expected =otions at specific sites using an analytical methodology.

The methodology, based on phy-

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sical principles, models the total earthquake process, including the generation of seismic energy for a partic-ular f ault source configuration and dimension as' well as

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the transmission of the seismic waves to the site.

Such state-of-the-art deterministic methods for

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computing ground motions are not presently applicable to most Eastern United States (EUS) sites, since many of the critical parameters associated with the majority of j

eastern seismic events, e.g.,

fault location, type, and dimension, etc., are not well known.

The basic reason for this lack of information is the absence of any evidence of

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DRAFT recent surface faulting that could be associated with the known seismicity.

In contrast to the Western United States, EUS events are likely occurring at sufficient depth with no surface expression and are not apparently 4

correlated to known surface geology.

In the absence of a i-satisfactory explanation of the seismicity in terms of surface geology, seismic networks and geophysical mapping techniques have been implemented to study the subsurface

.i in order to identify and ultimately quantify the seismo-genic regions in terms of their seismic potential.

To date, sufficient information has been accumulated to formulate several working hypotheses about the causes of seismicity in specific EUS regions, e.g.,

Cape Ann, Massachusetts, Ossipee, New Hampshire, New Madrid, I

Missouri, Attica, New York, etc.

?_

Because the present understanding of EUS seismicity j_

does not permit the discrimination of all active tectonic features, both with respect to past and future activity, the " tectonic province" approach, as defined by the USNRC l

in Appendix A, 10 CFR, Part 100, is the current method for determining the maximum ground motion potential at an EUS site.

MD 1

Weston Geophysical

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DRAFT

__ For most applications, the tectonic province approach i can be unrealistically conservative inasmuch as it assigns to every location a minimum seismic potential equal to the maximum historical earthquake.

Equivalently stated, the approach assumes that active faults with dimensions sufficient to support the maximum historical event are ubiquitous throughout the region.

This assumption contradicts the reality of the earthquake process which involves failures of crustal rocks along zones of weakness.

The presence of weaker zones necessarily implies the coexistence of zones of strength, which indeed are observed as aseismic stable blocks.

The clustering distributions of earthquakes in the EUS, as well as in other regions, support this contention.

Although the source of seismic potential for an EUS site cannot be more specifically answered than with those estimates made by application of the tectonic province methodology, the expected vibratory motion, can be more l~

realistically addressed with a site-specific approach than with the established practice of using generalized i

response spectrum shapes.

Current practice defines'the ground motion associated with the maximum earthquake Weston Geophysical w

_ ~ __. _

1 DRAPr

_4 potential by a standard response spectrum shape, e.g.,

USAEC Regulatory Guide 1.60, scaled to a "zero period" t

peak ground acceleration empirically determined for a maximum intensity estimated for a site.

Such practice involves questionable scaling procedures wherein strong motion records representing a wide range of magnitudes, i

intensities, distances, and site conditions are used to abstract a generalized spectral shape which is linearly scaled to model a wide range of seismic potentials.

This procedure provides unrealistic ground motion estimates except in those few cases in which the seismic setting is similar to the average conditions represented by the data set upon which the shape was based.

Thus, scaling standard response spectra shapes to model a seismic scenario which is not well represented by the original data set should-be avoided whenever possible.

The site-specific approach develops response spectra based on strong motion data selected under criteria that 1

closely model the parameters used to describe the occur-i rence of the maximum earthquake potential, as well as the

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plant site conditions.

Of the various parameters availa-ble to quantify an earthquake and, more specifically, the-W MD l

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d' 1

I DRAFT j

effects of a hypothetical earthquake at a site, those

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determined instrumentally are more reliable than any others based on noninstrumental evaluations.

For instance,-the magnitude and location of an earthquake-are i

i computed from instrumental-recordings.

Similarly, the strong ground motions observed at specific sites are f

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recorded on accelerographs, and the local geologic l

conditions at the sites can be well determined using geophysical surveys.

On the other hand, the Modified Mercalli intensity at an accelerograph site is not easily evaluated and generally is assigned the intensity level i

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j prevalent in the surrounding region.

By using accelerograms selected according to three

criteria, e.g.,

the magnitude of the event, the distance to the site, and the type of local geology, a range of expected ground motions at a site can be reasonably well

-established.

It should be noted that many more parameters i

influence the resulting site ground motion.

These include the fault mechanism, azimuthal directivity of the seismic 4

wave radiation pattern, stress drop, etc.

Therefore, I

ground motion estimates determined on the basis of only three parameters will exhibit significant scatter, which J

can be interpreted as a probability density function.of

.=

1 DRAFT

_ expected motions.

Consequently, the specification of the 4

design ground motion at the site will involve choosing I

from'the density function a probability-level that

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i adequately accommodates the uncertainty of the metho-dology.

The present' analysis used to predict ground motions at the Haddam Neck site follows the considerations outlined above and utilizes a site-dependent response spectrum approach.

l 2.0 THE SITE-DEPENDENT RESPONSE SPECTRUM METHODOLOGY f

The approach used to develop site-dependent response spectra for the Haddam Neck site is based on the evalua-

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tion of the seismic ground motion potential at the site, 4

i within the context of tectonic provinces and structures I

(10 CFR, Pa r t 100, Appendix A), in terms of magn'itude and

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'ocation (distance to the site) of the maximum earth-quake.

Accelerograms that approximate the magnitude and distance characteristics for the maximum earthquake, that l

were recorded at sites.similar to the Haddam Neck local site geology, are used for the computation of response spectra.

l j

Weston Geophyscal

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DRAFT, -.

Statistical processing of the response spectra data yield spectra that typify the ma<imum earthquake poten-tial.

Normalization or scaling of the data to peak

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acceleration or peak velocity is avoided, since the statistical processing is performed on the real response spectra computed from observeil time histories (accelerograms).

3.0 EVALUATION OF GROUND MOTION POTENTIAL AT THE HADDAM NECK SITE 3.1 Introduction The results of comprehensive investigations concerning the geologic history and seismicity of Eastern North America have been compiled in recent reports entitled

" Eastern United States Tectonic Structures and Provinces Significant to the Selection of a Safe Shutdown rarth-quake" (Weston Geophysical Corporation, 1979a), and 4

" Geology and Seiswology, Yankee RGwe Nuclear Power Plant" (Weston Geophysical Corporation, 1979b).

Other recent reports provide detailed descriptions of the seismicity

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data base currently maintained by Weston Geophysical.

l These include New York State Electric & Gas Corporation, i

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l Weston Geophyscal

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DRAFT Units 1 and 2, PSAR, 1978; Public Service Company of New Ilampshire, Seabrook Station, FSAR, August 1979; and Boston Edison Company, Pilgrim Unit 2, PSAR, 1976.

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Contained in these reports are the geologic, geophy-i_

sical, and seismologic bases for the definition of the tectonic framework in the Eastern United States with respect to the delineation of provinces and structures and their relative levels of seismic activity.

The evaluation i

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of the seismic ground motion potential at the fladdam Neck site is based upon this definition of,the tectonic 4

framework.

3.2 Regional Tectonic Framework 1

Detailed information on the tectonic framework and geologic evolution of eastern North America is contained in reports previously cited in Section 3.1.

Provinces l

located within 20'0 miles of the Haddam Neck site' include-l the following:

1.

Piedmont Atlantic Coastal Gravity Province (site province);

i 2.

Southeast New England Platform; r

3.

Western New England Fold Belt; 4.

Northeast Massachusetts Thrust Pault Complex; 5.

Coastal Anticlinorium; l

l Weston Geophysical Lo,

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DRAFT 6.

Merrimat Synclinorium; 7.

Adirondack Uplift; 8.

Eastern Stable Platform; 9.

Appalachian Plateau; 10.

Valley and Ridge.

The configuration of these provinces with respect to the Haddam Neck site and the locations of historical earthquakes are shown in Figure 1.

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Discussion will be limited to a review of the tectonics and seismicity of the first four provinces listed above.

Due to their proximity and th'eir level of seismicity, these four provinces have the greatest impact on the estimation of the ground motion potential at the site.

Descriptions of the remaining provinces can be found in a Weston Geophysical Corporation study (1979a).

Earthquakes w'ith epicentral intensities grea'ter than l

III or with magnitudes greater than 3.0, located within l

200 miles of the site, are tabulated in Appendix A.

l-3.2.1 Piedmont Atlantic Coastal Gravity Province - Site Province l -

Seismicity within the Piedmont Atlantic Coastal Gravity Province is of a moderate level.

The maximum intensity associated with historical earthquakes is

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VII(MM).

i-Weston Geophyscci

1 DRAFT _.

The seismicity of the immediate site region (50 km) is characterized as low to moderate.

The majority of the events are in the III-IV(MM) intensity range with several earthquakes of Intensity V(MM) and one, that of May 16, 1791, with an Intensity VI-VII(MM) (SER-Millstone II).

This earthquake, centered in the East Haddam-Moodus area of Connecticut, was originally categorized as an-Intens-ity VIII(MM), but was reevaluated as an Intensity V-VI(MM) by Reverend Daniel Linehan, S.J.

(1964).

For purposes of conservatism, it is treated in this study as being an In-tensity VI-VII(MM).

Geologically, this province is characterized by a Pre-cambrian basement overlain by Early Paleozoic metamorphic

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rocks which are locally intruded by plutons of Paleozoic age.

The province is characterized by basement rocks which are deforme'd into a nort'hesit-trending fabric re-sulting in a northeast-trending gravity high '(Figure 2).

Within the area of Paleozoic metamorphic rocks, structural basins of Triassic age occur from New Jersey to Georgia.

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A residual mantle of weathered rock exists throughout the province.

The boundary of the province is clearly defined on the west by-folds of the Valley and Ridge Province north of the James River, and by the thrust faults of the Southern i

Weston Geophysical

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DRAFT.

_i Appalachian Province south of the James River.

To the east, the province continues under a blanket of coastal plain sediments.

The southern boundary of the province is outside the area of this study and has not been invest-igated in detail.

Because of the thick sequence of rocks overlying the crystalline basement in this province, the regional gravity data (due in part to the basement rock)

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contribute significantly to the eastern and northern boundaries.

The gravity data generally correlate with and support the known regional geology.

3.2.2 Southeastern New England Platform Seismically, the province is characterized by

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generally low and scattered activity (Figure 1); the largest historical intensity is V-VI(MM) which is asso-ciated with the August 8, 1847, event.

Nonetheless, be-cause the 1791 East Haddam event, which occurred in the adjacent Piedmont Atlantic Coastal Gravity Province, is so

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close to the province boundary, the Intensity VI-VII(MM) associated with this event is conservatively accepted as the historical maximum.

The southeastern New England Platform lies south of the North Border fault of the Boston Basin and largely consists of Late Precambrian-Early Paleozoic granitic N

h Weston Geophysical

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DRAFT basement, with supractustal basins containing continental i_

sedimentary rocks (with minor interbedded volcanic units) ranging in age from older Paleozoic in the Boston Basin to Carboniferous in the Narragansett and reighboring basins of-Rhode Island and southeastern Massachusetts.

The plat-form is slightly deformed and does not have evidence of Acadian orogenic deformation.

In the Boston Basin, the

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sedimentary rocks have been folded and thrust-faulted from i

the south, with apparently thin-skinned tectonic deforma-tion (Billings, 1976).

In the southwestern part of the Narragansett Basin, in southeastern Rhode Island, deforma-I tion of the Carboniferous sr.dimentary rocks includes fold-

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l ing, metamorphism, and two episodes of east-west thrusting during the Paleozoic.

In eastern Connecticut, the Pre-cambrian rocks of the Southeastern New England Platform underlie a thin cover of pre-Silurian rocks beneath the Lake Char and Honey Hill fault surfaces.

Most of the platform rocks have been affected by an Alleghenian ther-mal or metamorphic event, locally including granitic plu-tonism.

The platform has not, howevar, been deformed in-ternally by throughgoing crustal fault structures.

The basement of fshore to the south, in the area of the Long Island Shelf (Schlee, 1977), slopes to the south and tum Weston Geophyscr2

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DRAFT is blanketed by a seaward-thickening wedge of loosely con-solidated Coastal Plain sediments of Cretaceous and Ter-tiary age.

Based on geophysical data, Sheriden (1974) has interpreted the basement of the Southeastern New England Platform to extend roughly 100 kilometers south to tne southern New England shoreline.

The southwestern boundary

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of.the province continues under Long Island where it is defined as the eastern edge of a distinct gravity high.

3.2.3 Western New England Fold Belt Province This province is defined as a separate seismosectonic province on the basis of geologic structure, geophysical signature, and a relative lack of seismic activity (Fig-ures 1 and 2).

Seismically, the province is characterized by a low level of infrequent activity (Figure 1).

Inten-sity V(MM) is representative of the historical upper limit of this province, even though, within the province, two 1 -

earthquakes of Intensity VI have occurred.

The first is the Quebec-Maine border event of June 15, 1973, associated with a seismotectonic structure, the Megantic intrusives of southeastern Quebec, one of the mafic intrusives of the White Mountain Plutonic Series.

The second one, although listed as Intensity VI(MM), must be characterized by a i

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much lower value.

This earthquake, which occurred on weston Geophysicot

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DRAFT January 30, 1952, near Burlington, Vermont, had an ex-tremely small felt area (50 square miles).

Such a small perceptible area is certainly not typical of events char-acterized by an Intensity VI(MM).

The probability is that this event was caused by freezing conditions as cracks were noted in the frozen ground near the Winooski River.

The occurrence of cryoseisms in New England is well known; these are very small events and have no effect on the se-lection of design earthquakes for a tectonic province.

The geologic structures which define the province are large-scale, north-northeast-trending thrust faults and folds of Paleozoic are.

Geophysically, the province is characterized in part by a pronounced north-trending gravity high in its axial region.

The eastern boundary of the Western New England Fold Belt is defined as the eastern termination of the north-south structures associated with the Bronson Hill Anti-clinorium.

The western boundary is placed along the limit of Paleozoic overthrusts which have been termed Logan's line or Logan's structure.

On the south, the province l

boundary is generally located along the western edge of a pronounced gravity high associated with the Piedmor;t Atlantic Coastal Gravity Province where the structural m

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DRAFT

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. features, as well as the seismicity, appear to change.

The northern boundary of the' province in eastern Quebec lies north of the study area.

3.2.4 Northeastern Massachusetts Thrust Fault Complex

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Seismically, this province is characterized by a dis-tinctive pattern of activity (Figure 1) which suggests that any seismic. event would tend to migrate along the trend of well defined geologic structures.

The largest earthquakes in the province (Intensity VIII) have been

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located where these northeast trends are disrupted, for example, at the mafic pluton of the White Mountain series of intrusives which is nearly in the middle of the off-shore continuation of the province.

The Northeastern Massachusetts Thrust Fault Complex is readily distinguished from neighboring provinces by its high frequency of post-Acadian faulting.

The complex is bounded on the northwest by the Clinton-Newbury fault, dated at Middle Permian (Public Service Company of New Hampshire, Seabrook FSAR, 1974), and is delineated on the southwest by the North Border fault of the Boston Basin.

The complex narrows and ends in a southwesterly direction based on both gec.ogic data and geophysical (aeromagnetic) signature; it can be projected for tens of miles to the Weston Geophysical

t DRAFT

. _. east on the basis of aeromagnetic patterns.

The predomi-

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nant pattern of deformation in the Complex is moderately to steeply northwest-dipping thrust faulting, commonly 1

with right-lateral, west-over-east displacements (Skehan, 1968; Dennen, 1978).

The Complex is a superimposed tectonic structural feature which exhibits extreme mechan-

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ical deformation of rocks both of coastal anticlinorium affinities (Goldsmith, 1978) to the north and of Avalonian affinities to the south.

The boundary between these two distinctive terranes is the Bloody Bluff fault system, the principal deep crustal fault of the complex (Nelson, 1976).

3.3 Estimated Seismic Intensities at the Haddam Neck Site The maximum ground motions at the site, in terms of Modified Mercalli intensities, were computed using an

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artenuation model. appropriate for the EUS.

Equation 1, l_

which is formulated on observed Modified Mercalli intensity attenuation for Central United States earth-quakes (Gupta and Nuttli, 1976), was used in this analysis.

I(R)

I

+ 3.7 - 0.00llR - 2.7 logR (R > 20km)

(1)

=

g l

Table 1 lists the parameters of the largest earth-quakes located in the Northeast, the distances of these i

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Weston Geophysical

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DRAFT

_ events to the site, and the estimated site. intensities as computed from Equation 1.

Equation 1 is formulated on intensity data observed at

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a variety of foundation conditions, most of which are soil sites that have experienced various degrees of local am-plification, due to the impedance contrast between soil layers and the underlying baserock.

Because of the manner in which Equation 1 was formulated, the predicted intens-

"1 ities at distance are best estimates at average foundation conditions, e.g.,

at sites overlain be some thickness of soils.

The intensity observed on sound foundations, e.g.,

rock foundation, as in the case of the Haddam Neck facil-ity, is lower than-the values predicted by Equation 1,

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since local soil amplification is not a factor at a rock i

site.

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The information in Table l' indicates that th'e maximum intensity on average foundation conditions in the immed-iate vicinity of the Haddam Neck facility, is a Modified

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Mercalli Intensity VI-VII.

On the basis of the previous discussion, the intensity at the-rock foundation at the site would be lower than a Modified Mercalli Intens-ity VI-VII.

ham.

Weston Geophysical

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DRAFT

.. The worst case scenario for ef fects at the site from hypothetical events located in adjacent provinces is as-sociated with an Intensity VIII earthquake located 100 km from the site at the southwest corner of the Northeast Massachusetts Thrust Fault Complex.

The Haddam Neck site intensity for this hypothetical event, using Equation 1, is Modified Mercalli Intensity VI.2.

On the basis of the site intensities listed in Table 1, and also on a review of the effects associated with hypothetical events located in adjacent provinces, the maximum ground motion potential at the Haddam Neck site is specified to be an Intensity VII at the site, re-sulting from the maximum historical earthquake known for the site province occurring at the site (at a focal dis-

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tance of 15 km).

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3.4 Recommen'dations for Magnitude and Distance of Design Earthquake As discussed previously, the maximum ground motion potential for the Haddam Neck site is an Intensity VII l

earthquake occurring at the site.

For the reasons dis-cussed in Section 1.0 of this report, and to facilitate i

i the data base search for appropriate accelerograms, it is

.necessary to convert this intensity to magnitude.

m.

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i Weston Geophysical

l-1 DRAFT Several empirical methods are available to estimate

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the body-wave magnitude of historical earthquakes from Modified Mercalli Intensity data.

One approach is to com-pute the magnitude from the observed maximum intensity.

This procedure is only approximate since the same inten-sity can be produced by earthquakes from a wide range of

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magnitudes, depending on the focal depth of the events and the local site amplification effects.

Another more refined approach, is to estimate mag-nit:1de from the total intensity pattern of the earthquake, rather than on the singular' determination of epicentral intensity.

The amount of energy released in an earth-4 quake, which is directly related to the definition of mag-nitudes, is assumed to be proportional to the affected area.

On this basis, empirical studies have produced formulae to estimate magnitude from perceptible areas (Nuttli and Zollweg, 1974; Nuttli et al, 1979).

The mag-

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nitude of the several intensity VII earthquakes in the site province have been estimated using both techniques.

l Weston Geophysical

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DRAFT r_

, muttli and Herrmann (1978) provide the following body

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wave magnitude-intensity relation for earthquakes occur-r i-in the Central United States:

I

= 2.0 m

- 3.5 (2) g b

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or conversely, i

b = 0.5 I

+ 1.75 (3)-

m g

i 1

Using Equation 3, an epicentral intensity VII earth-quake is converted to a magnitude 5.25, or rounded to 5.3 mb" I

_Next, the magnitudes of the intensity VII events in the site province, were computed from total felt areas, i

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Af, using Equation 4 (Nuttli et al, 1979).

l_

l m

= 3.25 - 0.25 log Ag + 0.098 (log Ag) 2 (4) bLg

[_

where Af = total felt area in square km i

Table 2 lists these computed magnitudes.

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i Weston Geophystal

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_. The magnitudes evaluated from the felt areas are smaller than the magnitudes calculated by converting ob-served intensities into magnitudes.

This suggests that observed intensities are somewhat anomalous.

This effect could be due to either a shallow focal depth for the evente, or more likely due to local amplification of quaternary coastal plain sediments occurring in the pro-vince or exaggeration of the historical intensities (Linehan, 1964).

As noted above, the amplification effect does not apply to the rock foundation condition for the-Haddam Neck site.

Although the largest earthquakes in the site province have magnitudes lower than 5.0 m, the historical occur-b rence of earthquake activity near the HadJam Neck site warrants some conservatism in the selection of the design earthquake magnitude.

For this reason the mean magnitude for the maximum earthquake potential is designated to be a 5.3 mb*

In the interest of making more records available for statistical analysis of spectral ordinates and definition of the density function of ground motion, the following Weston Geophysical

DRAFT criteria are defined as a range of magnituues and dis-tances for these events:

Magnitade Range Focal Distance Range (mb)

(km) 5.3 (10, 5) 15 (110)

Only accelerograms recorded on foundation c.nditions approximating the local site geology at Haddam Neck are accepted in the development of the site response spectrum.

Since the maximum earthquake is located near the site, parameters, such as fault orientation and mechanism could t

have significant effect on ground motions.

No formal treatment is attempted to account for these effects.

The manner in which all of the unknown parameters are accom-modated is through the choice of a conservative estimation of earthquake magnitude.

3.5 Haddam Neck Site Characteristics The Haddam site is underlain by the Monson gneiss and the Tatnic formation.

In the site area, the Monson gneiss is a light grey biotite-quartz-plagioclase gneiss with local occurrences of hornblende bearing gneiss; the Tatnic formation is a biotite-muscovite schist.

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Weston Geophysical

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A seismic survey performed by Weston Geophysical

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Engineers (1962) determined the compressional wave veloc-ity of the principal overburden to be 5,300 fps.

The velocity of the bedrock, which is the foundation of the Haddam-Neck plant, is in the range of 11,000 to 14,000 fps.

This velocity range indicates a rather competent rock.

The shear wave velocity of the bedrock is estimated

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to be in the range of 5,000 to 7,000 fps.

4.0 DERIVAT7.ON OF RESPONSE SPECTRA 4.1 Strong Motion Data Base United States agencies that disseminate digitized ac-celerograms include:

California Institute of Technology

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(CIT), Environmental Data Services for National Oceanic and Atmospheric Administration (EDS/NOAA) and United States Geologic Survey (USGS).

Weston Geophysical Corpo-ration (WGC) strong motion data base consists of all re-cordings that are available by these agencies.

This data

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j base includes recordings of earthquakes that have occurred i

l not only within the Western United States, but also in fl_

Japan, Italy, Peru, and Nicaragua.

Site characteristics of strong motion recording sta-tions have been the object of additional research.

The

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M 1

Weston Geophysico!

4 Z,.

r amount of information available on the foundation condi-tions of each station is highly variable.

It ranges from very general descriptions to detailed information includ-ing test borings and seismic surveys which provide data on 5

layer thicknesses, and compressional and shear wave veloc-ities.

For cases where details of recording site founda-tion conditions are not directly available, site founda-tion conditions have been estimated from available geo-logic maps, and where applicable, from geotechnical and geophysical data extrapolated from adjacent sites.

4.1.1 Data Base Search The strong motion data base was searched to find all recordings with parameters matching those used to charac-terize the maximum earthquake potential.

These parameters were defined as:

1.

Magnitude 5.3 (10, 5) mb L

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2.

Distance 15 (110) km 3.

Site Condition Competent Foundation Bedrock with Shear Wave Velocity of 5000-7000 fps.

The search provided twenty horizontal component re-

' ~1'-

cordings for seven different earthquakes.

Information l

i describing the selected accelerograph sites is presented 2j,

I in Table 3, while the earthquake identification parameters I4?h-

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bj; -

. y.

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Weston Geophysicol

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DRAFT and the peak accelerations observed at these sites are listed in Table 4.

A critical review of Tables 3 and 4 indicates that the selected strong motion data are in good agreement with the defined magnitude, distance and site conditions criteria, with only two exceptions.

First, on Table 3, the site l-conditions at the Cedar Springs Dam Pump House are des-cribed as " Shallow gravelly alluvium over granite."

The recordings obtained at that station were accepted despite that reference to alluvium, because numerous reviewers have classified the site as hard due to the shallow thick-ness of the overburden (Trifunac and Brady, 1975).

Second, on Table 4, the distance of the Temblor No. 2 sta--

tion is listed as 31 km, in excess of the established dis-i tance criterion.

The two accelerograms were nonetheless included in the set because the exact distance is con-sidered uncertain in view of the fact that the fault rup-ture was extensive.

An alternate measure of the distance

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i considers the nearest point of approach of the rupture; I

this is based on the fact that seismic energy is realeased l

all along the surf ace of dislocation.

Kanamori and Jennings (1978) in their study of Parkfield accelerograms have listed 10.7 km as the distance between Temblor No. 2 i

Weston Geophyscal

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t DRAFT and the nearest point of rupture; this distance is in agreement with the criterion.

For conservatism, the longer distance of 31 km was used in Table 4.

4.2' Data Processing The general outline of the methodology used to compute response spectra is described in the flow chart (Fig-ure 3).

As discussed previously, all recordings within the data base were not obtained from the same source.

~

Therefore, the degree of processing performed on the chosen records is not uniform.

The following sections discuss the general techniques used to generate response spectra.

4.2.1 Strong-Motion Signal Correction The data obtained from CIT and from EDS/NOAA were

~

already corrected for the instrument response, digitiz-ation errors, and' baseline drift and were ready 'for the l_

spectra-generation process.

However, the Friuli accelero-l grams were obtained in an uncorrected form, i.e.,

only l

l digitized and corrected for instrument sensitivity, scaled

' ~

to g/10.

l The general procedure and the computer program (EQCOR) used to correct these data are described in detail by l

~

Weston Geophysical

i DRAFT

_ Trifunac (1970) and Trifunac and Lee (1973).

Since publi-

~

cation of these reports, several advances have been made in the correction process; specifically, in the choices of the low-pass filter values (Basili and Brady,1978).

Their method requires that the pass-band of the filters for EOCOR be based on both the duration of the strong motion part of the record and length of the entire re-cord.

Previously, a standard pass-band (.07-25. Hz) was used for all records.

The quality of the correction pro-cess is determined by examining the computed displace-ments.

If long-period displacements are so large that they dominate short-period ones, the correction is con-sidered as inadequate because these long-period waves are actually unwanted noise.

If this is the case, new filters must be chosen to remove this long-period noise.

The choice of the pass-band becomes more critical for short

(-

duration, strong motion signals rich in high frequencies l

such as the Friuli sequences.

Examples of uncorrected i

l accelerograms are presented in Figure 4.

Figures 5 and 6 l

snow the corrected accelerograms for these records along with the computed velocity and displacement time histories.

l t

Weston Geophysical

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' DRAFT'

_ 4.2.2 Spectra Derivation Response spectra are plots of the maximum response of a simple oscillator (onc-degree of freedom) to ground acceleration as a function of the natural period ~and damp-ing of the oscillator.

The spectra are computed by solv-ing the equation of motion for the oscillator:

2 x + 2Sw x + w x = -a t where:

x is the relative displacement of the simple oscillator; at is base (ground) acceleration at time t; e is the natural frequency of vibrations of the oscillator; B is the fraction of critical damping.

The details of the derivation of the solution to this equation and the computational procedures involved are discussed by Nigam and Jennings (1968).

Examples of response spectra generated for the same records discussed in the previous-section are presented in

~

Figures 7 and 8.

-These are plotted at damping ratios.04 and.07.

Damping ratios-imply fractions of critical damp-ing;.07 damping ratio means the system is seven percent

. critically damped.

Euuum Weston Geophy1acci m-

I A

DRAFT

__ 4.3 Results:

Seismic Response Spectra

~

The response spectra of the twenty horizontal com-ponents listed in Table 4 were computed for several values of critical damping ~.

Spectra at 5% of critical damping are shown over-plotted in Figure 9.

The large scatter, more than an order of magnitude, in spectral accelera-

~

tions, velocity, and discplacement, observed in Figure 9, clearly demonstrates the probablistic nature of earthquake motions when defined on the basis of three parameters:

magnitude, distance, and site conditions.

The reason for the observed scatter is that encompassed by the general criteria is a variety of specific parameters of the earth-.

quake sources and transmission media that are primarily responsible for the observed motion.

The addition of more records according to the three criteria (magnitude, dis-tance, and site conditions) would not necessarily reduce the scatter, but would tend to reinforce it, since ad-

~~

ditional specific parameters, such as fault orientation, dimensions, stress drop, etc., previously not included would then come into play.

mest M

M Weston Geophyscal

2 DRAFT

.- s The task at hand, then, is to carefully examine the specific parameters of the selected earthquakes and re-sulting strong motion records to establish the extent to which they typify the earthquake potential accepted for the Haddam Neck site, and then on the basis of this re-view, to choose an appropriate design response spectrum

~

from the data shown in Figure 9.

An evaluation of the selected accelerograms suggests that even though these data meet the criteria, they nevertheless constitute a conservative estimate.of the ground motion at this EUS site.

The review of the data reveals that several of the recordings were obtained from earthquakes that produced surface faulting, e.g.,

the Oroville Earthquake, August 1, 1975; the Parkfield Earthquake, June 28, 1966.

Using these recordings to model EUS ground motion is con-servative since surface faulting is not characteristic of any eastern earthquakes observed to date.

Further examination fo the specific details of the selected data reveals that the most conservative aspect of the data set is the inclusion of the Temblor records for the Parkfield earthquake.

This earthquake has been ex-tensively researched due to the high accelerations re-

-~

corded near the fault.

Following is a summary of some important characteristics of this earthquake.

Weston Geophysical x

il t

DRAFT

, The magnitude of the Parkfield earthquake ranges

~

widely from 5.3m to 6.4M nd is typically assigned a b

s Richter magnitude of 5.5 or 5.6.

Filson and McEvilly (1967) who examined amplitude spectra for the event sug-gest that there was an uncharacteristic greater attenua-tion of high frequencies relative to longer periods,

~~

thereby making body wave magnitude estimate low at 5.3m Wu (1968) computed magnitudes of 5.8m and b.

b 6.4M f r the Parkfield event; therefore, the published s

material defines a range of body wave magnitudes for this event of 5.3 to 5.8m and a surface wave magnitude of b,

6.4Mg.

Analysis of the earhtquake mechanism suggests a fault rupture length of 30 km with the rupture propagating at 2.2 km/sec. towards the southeast (McEvilly et al, 1967; Filson and McEvilly, 1967).

Bouchon (1979) explains that l-the high accelerations recorded at an accelerograph near the fault trace is the result of this fault rupture pro-pagating toward the site.

Other analyses of the observed i

strong motion for the Parkfield earthquake indicate high acceleration-short duration motions near the fault with rapid attenuation with distance from the fault (Cloud and Perez, 1967).

l _

SEIW Weston Geophysical 6

t i

DRAFT

__ The particular characteristics of the Parkfield earth-

~

quake, including the long fault length, extensive surface rupture, and large surface wave magnitude do not represent the design earthquake recommended for the Haddam Neck site.

Furthermore, the occurrence of a large ground motion resulting from the directivity effect of the fault

~

rupture propagation is regarded as a remote probabilistic event at the Haddam Neck site, since no active faults are currently known.

For these reasons, the use of the Temblor records consitutes a conservative assessment.

The amount of conservatism that results from the in-

~

clusion of the Parkfield earthquake can be evaluated by th i

computing the mean and 84 percentile peak accelera-tions for the data in Table 4, excluding the Temblor re-cords.

The log normal mean peak acceleration of the 18 remaining records is 74.0 cm/sec, a reduction of 22%,

th while the 84 percentile peak acceleration is 2

107.5 cm/sec, a reduction of 27%.

The previous discussion illustrates the conservative l

aspects of the Temblor records and their effects on the computed average spectral level.

On this basis, the data set is regarded to be a conservative representation of the

-~

expected ground motions at Haddam Neck.

Tne choice of an l

Weston Geophys4 cot

2 DRAFT

_. appropriate design response spectrum considerd this fact,

~

while also taking into account the critical nature of the nuclear plant design and accomodating the uncertainty inherent in the methodology of predicting strong ground motion from small data samples.

Considering these factors, the log-normal mean

~

response spectrum computed for the 20 accelerograms listed in Table 4, is a conservative assessment of the design response spectrum appropriate for the Haddam Neck site.

th Figure 10 shows the log normal mean and 84 percentile response spectra for five percent critical damping.

It should be noted that not all 20 components were averaged at all periods.

The number of spectra averaged decreases with increasing period since each accelerogram has its own pass-band selected during the correction process (see Section 4.2.1).

Table 5 shows the actual number of spectra averaged in various period ranges.

The irregular shape of the recommended design spectrum, which has a pronounced spectral gap in the period range of 0.4 to 1.2 sec., is interpreted as a statistical gap resultant from averaging a small data sample, rather than a real characteristic of spectra ob-served at short distance at rock sites.

The inclusion of M

M Weston Geophysical

t

\\

DRAFT additional suitable records would tend to smooth out the

~

peaks and troughs; therefore, the recommended design spec-trum is visually smoothed as the envelope of the peaks in the log normal mean curve.

Figure 11 shows the final re-commended smoothed design response spectra, plotted at various levels of critical damping.

~~

Pinally, the recommended site-dependent response spec-trum is compared in Figure 12 to several other specifica-tions of response spectra for the Haddam Neck site.

These include the original design spectrum at Haddam Neck, the 1

Regulatory Guide 1.60 shape anchored to.219, and the i

NUREG 0098 shape anchored to the USNRC SEP Task Plan A-40

~

recommendations of.219 peak acceleration for the Haddam l

Neck site.

5.0 CONCLUSION

i It is concluded from this research that the recom-mended site dependent response spectra constitute a more

~

l realistic representation of the grcund motion than those l

of the standard Regulatory Guide 1.60 and NUREG 0098 shapes, while also affording an appropriate level of con-servatism required in the design of critical facilities.

l-Figure 12 also illustrates that the original seismic de-sign of the Haddam Neck facility is adequate and conserva-tive.

Weston Geophyscal

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The list of references will be included in the final report.

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TABLE 1 LARGEST EARTHQUAKES IN THE NORTHEAST REGION AND THEIR EFFECTS AT THE HADDAM NECK SITE Year Month Day Lat. (N)

Long. (W)

Io Distance Estimated Province / Structure (km)

Site Intensity 1966 Feb.

5 47.6 70.1 X

705 5.2 LaMalbaie Structure l

1727 Nov.

9 42.8 70.6 VII 214 4.2 Northeast Massachusetts Thrust Fault Complex 1732 Sep.

16 45.5 73.6 VIII 455 4.0 Western Quebec Seismic Zone 1737 Dec.

18 40.8 74.0 VII 146 4.7 Site Province 1 1755 Nov.

9 42.8 70.6 VIII 226 5.1 Northeast Massachusetts Thrust Fault Complex 1774 Feb.

21 37.3 77.4 VII 626 2.5 Site Province 1791 May 16 41.5 72.5 VI-VII 2

6.0-7.0 Site Province 1840 Nov.

11 39.8 75.2 VII 294 3.7 Site Province l

1875 Dec.

23 37.6 78.5 VII 670 2.3 Site Province 1884 Aug.

10 40.6 74.0 VII 159 4.6 Site Province i

1927 Jun.

1 43.3 73.7 VII 182 4.4 Site Province 1931 Apr.

20 43.4 73.7 VII 235 4.0 Adirondack Uplift 1940 Dec.

24 43.8 71.3 VII 275 3.8 White Mtn. Plutonic Series 1940 Dec.

24 43.8 71.3 VII 275 3.8 White Mtn. Plutonic Series g

I c l 3 1944 Sep.

5 44.97 74.9 VIII 433 4.1 Western Quebec Seismic zone i O o

3 f

ISite Province = Piedmont Atlantic Coast Gravity Province 9.

TABLE 2 INTENSITY VII EARTHQUAKES WITHIN PIEDMONT ATLANTIC COASTAL GRAVITY PROVINCE Year Month Day Lat.

Long.

Epicentral Felt Area Converted (N)

(W)

Intensity Km2 mbLg 1737 12 la 40.8 74.0 VII NA 1774 02 21 37.3 77.4 VII 150,000 4.6 1791 05 16 41.5 72.5 VI-VII 90,000 4.4 1840 11 11 39.8 75.2 VII NA 1871 10 09 39.7 75.5 VII NA 1875 12 23 37.6 78.5 VII 130,000 4.5 1884 08 10 40.6 74.0 VII 180,000 4.6 1927 06 01 40.3 74.0 VII 8,000 3.8 t

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TABLE 3 SITE CONDITIONS OF SELECTED ACCELEROGRAPH STATIONS Instrument Site Name Location Type Characteristics Carroll College Helena, Montana Hard Rock 4 Temblor No. 2 Parkfield, California AR-2401 Serpentine and fractured ultrabasic complexl l

l Oroville Northern California S-MD1 Metavolcanic Schist Seismograph Station l

Cedar Springs Southern California AR-2402 Granite 2 Allen Ranch

^

Cedar Springs Dam Southern California AR-2402 Shallow gravelly allu-Pump House vium over granite 2 l

Somplago D Friuli, Italy SMA-1 (.259 range, Fractured lime-turbine level)3 stone and dolomite P-vel 4300 m/sec3 San Rocco Friuli, Italy SMA-13 Fissured limestone 3 I

j World Data Center A(1979) 2 udson (1971)

H 3 uzzi and Vallini (1977)

M 4Chang (1978) kg 5Silverstein (1978) a l

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TABLE 5 NUMBER OF RE3PONSE SPECTRA ORDINATES

~

AVERAGED IN 7ARIOUS PERIOD RANGES 4 _

Period Number of Response (sec)

Spectra Ordinates

.04.09 20 i

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.91-1.0 18 i

1.2 14 1.6-2.0 10 2.4-7.2 8

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REGIONAL TECTONIC AND SEISMOTECTONIC PROVINCES

[ PROVINCE BOUNDARY ( DASHED LINE INDICATES RELATIVE UNCERTAINTY OF BOUNDARY)

EARTHQUAKES

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MAGNITUDE INTENSITY (1930 throughl%7)

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NOTE SEISMICITY BASED ON DATA AVA'L ABLE AS OF JANUARY 1979.

m FIGURE 1 EARTlicVAKES WITH (SEISMO) TECTONIC PR071NCES/

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STRUCt'JRES OF NORTHEASTERN AND NORTH-CENTRAL. UNITED STATES.

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MAGNITUDE INTENSITY te tral cattes statu a.e so tan a c..asa, c o ettes (1930 through 1967)

(cf ter I 1-68)

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Gravity 16.

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sowt.eastera Geelag,. vol.

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T i

XII t

NOTE SEISWCITY BASED ON DATA AVAILABLE AS OF I

JANUARY 1979.

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APPENDIX A l

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i weston Geophysical 4

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~~

APPENDIX A PAGE A-1 EARTHGUANES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAN NECK SITE DATE CRIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lons(W) MM Scale ab ML To Site (km)

---== =------------------- =_= -_. =--

164,-

611 13 0 42.800 70.800 IV 202.4 1677 1213 00 41.050 73.530 IV 98.4 1685 218 00 42.700 70.800 IV 194.6 1705 627 00 42.350 71.060 IV 153.0 1727 11 9 2240 42.800 70.600 VII 214.1 1727 11 9 2335 42.800 70.600 IV 214.1 1727 1110 215 42.800 70.600 IV 214.1 1727 1114 17 0 42.800 70.600 V

214.1 1727 1118 1120 42.800 70.600 IV 214.1 1727 12 1 00 42.800 70.600 IV 214.1

-1727 1216 00 42.800 70.600 IV 214.1 172712191'd0 42.800 70.600 IV 214.1 1727 1228 2230 42.800 70.600 IV 214 1 1728 1 4 23 0 42.800 70.600 V

214.1 1728 2 4 2130 42.800 70.600 IV 214.1 1728 28 630 42.800 70.600 IV 214.1 172S 210 1530 42.800 70.600 V

214.1 1728 516 0 0 42.800 70.600 IV 214.1

~~

1728 730 10 0 42.800 70.600 IV 214.1 1728 -8 2 315 42.800 70.600 IV 214.1 Weston Geophyscal

8

)>

AFFENDIX A PAGE A-2 EARTHQUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0

~~

LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTAHOE Year MoDa HrMn Lat(N) Leng(W) MM Scale ab ML To Site (km) 1729 330 14 0 42 800 70.600 IV 214.1 1729 86 00 41.400 73.500 IV 83.7 1729 1125 80 42.800 70.600 IV 214.1 1729 12 8 20 0 42.800 70.600 IV 214.1 1730 39 145 42.800 70.600 IV 214 1 1730 423 20 0 42.800 70.600 IV 214 1 1731 112 19 0 42.000 70.600 IV 214.1 1731 122 24 0 42.800 70.600 IV 214 1 1731 1012 23 0 42.800 70.600 IV 214.1 1736 1123 20 42.800 70.600 IV 214 1 1737 920 1020 42 000 70.600 IV 214.1 1737 1218 00 40.800 74.000 VII 146.4 1744 614 1015 42.500 70.900 VI 173.7

~~

1744 614 17 0 42.520 70.920 IV 173.9 1755 1118 412 42.700 70.300 VIII 226 0 1755 1118 529 42.700 70.300 IV 226.0 1755 1122 2027 42.700 70.300 V

226 0 1755 1219 2015 42.700 70.300 IV 226.0 1757 7 8 1430 42.350 71.100 IV 150.5 1761 11 1 20 0 43.100 71.500 IV 197.5

=___________________

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'~

APPENDIX A PAGE A-3 EARTHOUAKES WITH INTENSITY > III GR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lons(W) MM Scale ab ML To Site (km)

'1 1766 1217 1840 43.100 70.800 IV 227.4 1783 1129 1050 41.000 74.500 VI 175.2 1790 725 50 41.450 72.410 IV 4.9 1791 516 80 41.500 72.500

- VII 2.0 1800 1220 00 43.700 72.300 IV 246.7 1801 3 1 1530 43.070 70.770 IV 226.4 1805 425 1820 42.500 70.900 IV 173.7 1807 113 23 0 43.000 71.000 IV 208.7 1807 56130 43.480 70.470 IV 277.1 1810 11 9 2115 43.000 70.800 V

218.8 1814 1128 1914 43.700 70.300 V

304.8 i

VI 155.8 1817 10 5 1145 42.500 71.200 V

221.7 1823. 723 655 42.900 70.600

~~

V 19.0 1827 823 00 41.400 72.700 1837 115 70 42.500 70.950 IV 170.6 V

29.3 1837 412 00 41.700 72.700 4

5 1840 116 20 0 43.000 75.000 VI 265.6 1840 8 9 1530 41.500 72.900 V

33 3

~~

1840 1111 00 39.800 75.200 V

294.2 1845 1026 1815 41.200 73.300 VI 73.6

^

Weston Geophysical

8 Is

~~

APPENDIX A PAGE A-4 EARTHOUANES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECX SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Long(W) HM Scale sb ML To Site (km) 1845 11 0 00 43.600 72.300 IV 235 7 1846 530 1330 42.700 70.300 IV 226.0 1846 825 445 42.500 70.800 V

180.1 1847 8 8 10 0 41.700 70.100 VI 200.6 1847 929 00 40.500 74.000 V

166.3 1848 98220 40.400 74.000 V

173.9 1852 110 1140 41.200 71.400 IV 96.8 1852 1127 2345 43.000 70.900 V

213.7 1854 1024 22 0 42.900 72.300 IV 158.3 1854 1211 030 43.000 70.800 V

218.8 1855 116 18 0 44'.000 71.000 V

305'.1 1855 116 1920 44.000 71.000 IV 305.1 l

l 1855 2 6 2330 42.000 74.000 V

136.9

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1855 1217 14 0 43.300 73.700 IV 224.5 1856 312 22 0 41.400 72.600 IV 12.3 1858 630 2245 41.300 73.000 V

46.3 1862 2 2 20 0 41.500 72.500 IV 2.0 1871 720 00 43.200 71.530 IV 206.6 1871 10 9 940 39.700 75.500 VII 321.0 1872 711 525 40.900 73.800 V

126.3 weston Geoprysical

5

!\\r APPENDIX A PAGE A-5 EARTHQUAKES WITH INTENSITY > III OR HAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY HAGNITUDE DISTANCE Year HoDa HrMn Lat(N) Lons(W) MM Scale ab HL To Site (km)

=-

1872 1110 14 0 43.200 71.600 V

204.5 1874 16 00 43.600 71.200 IV 258.0 1874 125 12 0 42.600 71.350 IV 156.1 3

1874 1124 00 42.700 70.900 IV 188.8 1874 1210 2225 40.900 73.800 VI 126.3 1875 728 410 41.900 73.000 V

62.2 1875 12 1 00 42.900 72.300 IV 158.3 1876 921 2330

<*.S30 71.200 V

101.5 1877 910 959 40.300 74.900 V

240.3 1878 2 5 1120 40.000 73.800 V

197.5

'j 1878 10 4 230 41.500 74.000 V

124.7 l --

1879 1025 2'230 42.980 71.470 IV 186.6 1880 512 745 42.700 71.000 V

183.1 l--

1880 720 19 0 42.980 71.470 Th 186.6 1881 10 6 53 43.200 71.550 It 206.0 l

1882 417 00 43.200 71.700 IV 201.7 Ij--

1882 1219 1724 43.200 71.400 V

211.0 l

l 1883 2 4 20 5 43.600 71.200 IV 258.C l --

l 1883 227 2330 41.500 71.300 V

99.8 l

1884 118 70 43.200 71.700 IV 201.7

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'Neston Geophyscal

+-

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APPENDIX A PAGE A-6 EARTHQUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE-Year MoDa HrMn Lat(N) Lons(W) MH Scale ab ML To Site (km) 1884 531 00 40.600 75.500 V

269.5 1884 810 19 7 40.600 74.000 VII 159.2 1884 811 00 40.600- 74.000 V

159.2 1884 1112 00 43.200 71.550 IV 206.0 1984 1123 1230 43.20C 71.700 V

201.7 1884 1217 00 43.700 71.500 IV 259.4 1886 1 5 1910 42.900 71.500 IV 177.6 i --

1886 117 1714 42.770 71.450 IV 167.1

~~

1836 125 00 41 580 73.800 IV 108.5 1997 630 21 0 43.200 71.530 IV 206.6 1889 38 00 43.450 71.580 IV 231.1 1889 810 00 43.430 73.720 IV 238.2 1891 5 1 1910 43.200 71.600 V

204.5 I

i 1891 529 19 0 43.100 71.500 IV 197.5 1892 1211 1130 44.300 71.700 IV 319.5 1893 39 030 40.600 74.000 V

159.2 l __

1893 314 00 42.350 72.660 IU 97.2 l

1894 410 00 41.600 72.500 IV 13.1

~~

1894 1217 00 42.470 73.800 IV 153.4 1895 91 69 40.700 74.800 VI 211.0 1

Weston Geophysical

'9 hs APPENDIX A PAGE A-7 EARTHOUAXES WITH INTENSITY > III OR MAGNITUDE > 3.0

'~

LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lons(U) MM Scale ab ML To Site (ks)

_=_ ___

IV 285.8 1896 521 228 43.080 75.230 1896 1022 530 44.300 71.770 IV 318.4

~~

1897 71 420 43.700 71.600 IV 256.9 1897 95 00 41.500 72.500 IV 2.0 1898 611 145 42.830 72.560 IV 149.7 1899 516 2015 41.600 72.600 V

15.5 1903 424 1230 42.700 71.000 IV 183.1

~ ~ -

1905 830 1040 43.100 70.700 V

232.6 1905 1126 030 41.500 71.300 IV 99.8 1906 C 8 1330 41.500 72.500 IV 2.0 l

1906 1019 00 43 500 70.500 IV 277.4 l--

1907 124 1130 42.800 74.000 IV 191.4 1907 629 00 43.500 70.500 IV 277.4 1907 1016 010 42.800 71.000 V

191.4 1908 531 1742~ 40.600 75.500 VI 269.5 l

1909 1123 13 0 43.450 71.650 IV 229.3 1

i 1910 123 130 43.800 70.400 IV 309.2 1910 821 1845 42.700 71.100 IV 177.7 j

l __

l 1910 830 1430 43.400 72.100 IV 215.4 I

1211 3 2 2130 43.200 71.530 IV 206.6 I

Weston Geophysacol

l

');

'~

APPENDIX A PAGE A-8 EARTHOUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lons(U) HM Scale ab ML To Site (km)

-- _-- - - - - _ _ _ - - - - - - - = - - _ = = - - -

=-

=-------------

1913 810 515 44.000 74.000 IV 305.1 1913 11 3 1430 41.400 71.400 IV 91.9 1915 221 23 42.800 71.100 IV 186.2-1916 1 5 1356 43.700 73.700 V

265.0 1916 2-3 426 43.000 74.000 V

208.7 1916 6 8 2115 41.000 73.800 IV

_120.9 1916 11 2 232 43.300 73.700 V

224.5 1916 12 2 90 41.500 72.450 IV 4.6 1917 216 90 41.500 72.450 IV 4.6 1919 811 00 41.470 72.450 IV 4.4 s

1920 523 80 43.100 71.500 IV 197.5 1921 119 10 0 43.300 73.700 IV 224.5 1921 126 2340 40.000 75.000 V

266.9

'~

1921 127 00 43.300 73.700 IV 224.5 1922 5 7 2240 43.400 71.400 IV 231.2 1925 1 7 13 7 '42.600 70.600 V

199.8 1925 39 00 42.930 71.470 IV 181.7 1925 424 756 41.700 70.800 V

143.1

~~

1925 10 9 1355 13.700 71.100 VI 271.5 1925 1029 00 41.500 72.450 IV 4.6 mg' Weston Geophysacol

8 9h*

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APPENDIX A PAGE A-9 EARTHOUAKES WITH INTENSITY > III OR NAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year doDa Hrnn Lat(N) Lons(W) ' MM Scale

.sb HL To Site (ks.)

---

==_

1925 1114 13 4 -41.700 72.400 V

25.6 1925 1116 620 41.770 72.700 IV 36.0 1926 1 4 00 41.600 71.800 IV 59.6 1926 126 2340 40.000 75.000~

V 266.9 1926 -318 21 9 42.800 71.800 V

157.2 1926 512 330 40.900 73.900 V

133.6 1927 39 48 43.300 71.400 V

221.0 1927 330 00 41.670 72.780 IV 31.2 1927 6 1 1223 40.300 74.000 VII 181.8 1927 820 -0 0 42.300 71.000 IV 153.6 1928 113 1950 41.200 71.600 IV 81.2 1928 428 22 7 43.200 71.500 IV 207.6 1$ 30 214 615 43.400 71.700 IV 222.7

~~

1930 319 015 43.300 71.600 IV 214.9

'1931 420 1954 43.400 73.700 VII 4.7 5.0 234.5 1931 71 245 41.600 73.400 IV 75.9 1933-117 530 41.630 70.930 IV 131.4 1933 125 20 40.200 74.700 V

233.1 1933 1029 00 43.000 74.700 IV 247.1 1934.130 1030 41.800 72.600 IV 36.3

. em.

Weston Geophyscal

'{ 1 e -.

~~

APPENDIX A PAGE A-10 EARTHGUANES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year McDa HrMn Lat(N) Lons(U) MM Scale sib ML To Site (km)

- - _ - - - - = _ _.

1934 8 2 1458 42.600 70.700 IV 193.4 1934 8 2 1459 43.700 70.300 IV 304.8 1934 83 230 43.700 70.300 IV 304.8 1935 424 124 42.170 70.220 IV 203.4 1936 1110 246 43.550 71.430 V

245.7 1937 719 351 40.720 73.710 IV 131.9 1937 727 910 41.830 72.430 IV 39.1 1938 623 357 42.620 71.420 IV 154.5

~~

1938 82 92 41.080 73.700 IV 109.6 1938 823 336 40.100. 74.500 V

3.9 4.6 227.5 2

1938 623 54 40.250 74.250 4.0 4.8 200.7 1938 823 73 40.250 74.250 3.7 4.6 200.7 1939 1115 254 39.600 75.200 V

309.0

~~

1940 128 2311 41.630 70.800 V

2.6 4.3 142.1 I

1940 3 2 415 41.500 72.500 IV 2.0 1940 313 129 41.500 72.500 IV H2. 0 1940 1220 727 43.800 71.300 VII 5.4 5.8 275.3 1940 1224 1343 43.800 71.300 VII 5.4 5.8 275.3

~~

1940 1225 53 43.800 71.300 3.7 4.0' L275.3 1940 1227 1956 43.800 71.300 3.8 3.9 275.3

- = _ - - - = - - -.

==_--- _=-

h Weston Geophysical

i 3E

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APPENDIX A PAGE A-11 EARTHOUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DIGTANCE Year McDa HrMn Lat(N) Lons(U) MM Scale ab ML To Site (ks,)

__- - = ______=--

1941 121 227 43.800 71.300

.2.8 3.6 275.3 1942 1024 1727 40.970 75.250 3.4 236.4 1943 314 14 2 43.700 71.570 3.9-257.7 1944 2 5 1622 40.000 76.200 37 318.3 1944 1214 315 41.600 72.800 IV 3.5 28.1 1947 1 4 1851 41.030 73.580 IV 103.1-1948 54 223 41.380 71.830' IV 56.9 1949 417 015 41.600 71.500 IV 84.1

~~

1950 320 2255 41.500 75.800 3.3 274.3 1950 329 1443 41.050 73.600 IV 103.5 4

1951 126 327 41.500 72.500 IV 2.0 1951 331 350 42.200 72.200 IV 83.5 1951 610 1720 41.500 71.500 IV 83.1 1951 9 3 2126 41.250 74.250 V

3.8 4.4 148.0-1951 1123 645 40.600 75.500 IV 269.5 1952 825 07 43.000 74.500 V

235.3 1952 10 8 2140 41.700 74.000 V

126.0

.1953 327 850 41.100 73.500 V

3.0 93.5 1953 331 1258 43.700 73.000 V

4.0 249.6 1953 511 613 43.980 71.130 IV 298.9 As Weston Geophysicat -

4' APPENDIX A PAGE A-12

~ ~ -

EARTHQUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE

~~

DATE-ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lons(W) MM Scale ab ML To Site (km)

_ - - - - - - - _ _-=------_-----

---==

1953 817 422 41.000 74.000 IV 136.1 1954 17 725 40.300 76.000 VI 321.6 1954 331 2125 40.250 74.000 IV 185.9

'~

1954 729 1957 42.700 70.700 V

4.0 200.6 1955 121 840 42.970 73.780 V

195.8 1957 323 19 2 40.630 74.830 VI 216.7 1958 5 6 19 0 42.650 73.820 IV 169.2 195E 919 1745 43.600 70.200 V

301.0

-~

1958 1121 2330 43.970 71.680 IV 284.1 1959 413 2120 41.920 73.270 3.4 80.2 1960- 122 2053 41$500 75.500 3.4 249.'4 1961 914 2117 40.750 75.500 V

4.3 263.6 1961 1227 17 6 40.500 74.750 V

4.3 217.7 1962 410 1430 44.100 73.400 V

5.0 299.7 1962 1229 619 42.800 71.700 V

4.3 160.4 1963 3 2 2024 41.510 75.730 3.4 268.5 1963 519 1914 43.500 75.230 3.5 316.3 1963 7 1 1959 42.570 73.750 3.3 158.7 1963 1016 1531 42.500 70.800 V

3.9 4.2 180.1 1963 1030 1736 42.700 70.800 V

2.4 5.0 194.6

---

=--

W-Weston Geophysical e.

\\-

4

~~

APPENDIX A PAGE A-13 EARTHQUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0-LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EFICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lons(W) MM Scale ab ML To Site,(km)

- =___ _-- -- -

1963 12 4 2132 43.600 71.600 V

3.7 246.3 1964 4 1 1121 43.600 71.500 IV 1.8 248.9 1964 626 11 4 43.300 71.900 V

2.6 3.6 207.7 1964 1117 17 8 41.200 73.700 V

4.3 104.8 1965 929 1557 41.400 74.400 IV 158.3 1965 1024 1745 41.300 70.100 V

4.3 200.8 1965 12 8 33 41.700 71.400 V

4.3 94.4 1966 1023 23 5 43.000 71.800 V

3.1 178.0 1967 2 2 1340 41.400 71.400 V

2.4 91.9-I 1967 515 2247 42.300 69.900 3.2 233.2 1967 1122 2210 41.200 73.800 V

112.7 1968 11 3 833 41.400 72.500 V

9.1 1968 1210 412 39.700 74.600 V

2.5 265.4 1969 86163 43.800 71.400 V

272.5 1969 10 6 00 41.000 74.600 IV 183.2 1970 919 1335 42.950 71.870 IV 171.0 1971 1021 054 42.700 71.150 V

175.0 1973 228 821 39.720 75.440 V

3.8 315.6 1974 428 1419 39.750 75.550 IV 320.9 1974 6 7 1945 41.570 73.940 3.3 120.0 l

sw I

Weston Geophysical

2 > '%.

4 i

APPENDIX A PAGE A-14 EARTHOUAKES WITH INTENSITY > III OR MAGNITUDE-> 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE.

DATE ORIGIN EPICENTER INTENSITY MAGN:iUDE DISTANCE Year MoDa HrMn Lat(N) Lens (W) uMM 5cale s,'

ML

'o Site (km) 1975 11 3 2054 43.890 74.640~

3.9 319.2 1975 11 3 21 6 43.890 74.650 4.0 319.7-

~~

1976 311 829 41.560 -71.210 3.5 107.5 1976 413 1539 40.800 74.030 3.1 148.6 1976 424 1022 41.460 72.490-IV.

2.2 2.6 1976 510 134 41.540 71.010 V

2.7 124.0.

1977 1220 1744 -41.822 70.758 IV 3.1 149.3' 1977 1225 1535 43.200.71.641 IV 3.2 203.3 i

~

THIS CATALOG CCNTAINS 268 EARTHGUAKES I

WeWon Geophysocol

.J

)

'w k

4 APPENDIX A PAGE A-14

~'

EARTHOUAKES WITH INTENSITY > III OR MAGNITUDE > 3.0 LOCATED WITHIN 200 MILES (322 KM) 0F THE HADDAM NECK SITE DATE ORIGIN EPICENTER INTENSITY MAGNITUDE DISTANCE Year MoDa HrMn Lat(N) Lens (W) MM Scale ab ML To Site (km) 1975 11 3 2054 43.890 74.640 3.9 319.2 1975 11 3 21 6 43.890 74.450 4.0 319.7 1976 311 829 -41.560 71.210 3.5 107.5 1976 413 1539 40.800 74.030 3.1 148.6 1976 424 1022 41 460 72.490 IV 2.2 2.6 1976 510 134 41.540 71.010 V

2.7 124.0 1977 1220 1744 41.822 70.758 IV 3.1 149.3 1977 1225 1535 43.200 71.641 IV 3.2 203.3 THIS CATALOG CONTAINS 263 EARTHOUAKES

- Weston Geophysical

_