ML20151P854

Cascadia Subduction Zone,Some Unresolved Problems, Presented at 880506-08 Meeting in Seattle,Wa

ML20151P854
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	05/06/1988
From:	Lewis B WASHINGTON, UNIV. OF, SEATTLE, WA
To:
Shared Package
ML20151H012	List: ML20151H010 ML20151H017 ML20151H028 ML20151H047 ML20151H066 ML20151H071 ML20151H077 ML20151H080 ML20151H093 ML20151H106 ML20151H111 ML20151H116 ML20151H122 ML20151H126 ML20151H138 ML20151H144 ML20151H147 ML20151H159 ML20151H170 ML20151H176 ML20151H185 ML20151H197 ML20151H213 ML20151H217 ML20151H229 ML20151H240 ML20151H253 ML20151H263 ML20151H272 ML20151H275 ML20151P543 ML20151P567 ML20151P703 ML20151P721 ML20151P744 ML20151P748 ML20151P767 ML20151P772 ML20151P775 ML20151P793 ML20151P805 ML20151P816 ML20151P819 ML20151P833 ML20151P842 ML20151P847 ML20151P854 ML20151P858 ML20151P861 ML20151P866
References
NUDOCS 8808100207
Download: ML20151P854 (1)

Text

. 18 The Cascadia Subduction Zone, Sctre unresolved problers.

Brian T.R.14wis School of Oceanography University of Washington The recurrence time of subduction earthquakes depends on at least the following. The strength of the driving force, the gectnetry of the i subduction zone, tarperatures in the subduction zone, and asperities on the thnist fault.

If the driving force is the negative bouyancy of the sinking plate then

, to ascertain its strength, we must know the history of subduction in the area, the gecrretry, tertperature and densities in the sinking slab, and the viscosity unkr.own.

of the medium into which it is sinking. All of these are largely 1 1

1 The gecmetry of the subduction zone is inportant because the frictional -

forces resisting subduction riepend on the mass of the overlying material, that is the gecrretry. This gecmetry is largely unknown, but probably not  !

constant along the Oregon /Washir/jton trargin and this cculd influence the recurrence time.

Tenperatures along the thrust zone are clearly inportant in determL*g whether the material is in the brittle or plastic regime, and therefore whether subduction is aseismie or not. Sediment heat flow values predict very high tenperatures based on conductive heat flow. If advection of heat by porous flow is significant the teiperatures could be r.uch lower.

Asperities can alter the recurrence time significa*itly. We know very little about asperities in general, and little about t'.e Cascadia area specifically. Are the Olyrtpic mountains an asperity ?

l P

__ _ _ . - - - . -