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( <br /> � Sh:illu�c Crustal ICartliyu:�l:cs. Sh:illu�� cru,t;il curthyir�l:r� uccw' ��ilhin thc Aonh �Amcrir.m Pl.11c �a <br /> dcpths up to I� milcs. Shullo�o� �urthqut�kcs in �cestcm 11`;ishington urc csp�•cted ro hncc d�.�ruti�,n; <br /> � ranging up to 60 seconds. Pour ma^__niuide 7 or �_mater kno��n carthquakes h;rve occurred in d�e I:at <br /> 1.100 years in the Cascadia region, t�vu of these occurred on Vancouver Island and hvo in ��estcrn <br /> �Vashim�ton. <br /> � Thc largcst hisroric carthquakc in ��cstern \1'asliin!![on oceurrcd in 1872 in [he �orth Cascadcs :mJ i�. <br /> estimated to have had a magnitude of 7.-1. This earthquake is belicved to have occurred at a deptL �,�Ic;s <br /> � than 10 miles. fhe othcr magnitudc %' ���stern �\'ashin�=ton c�rdiquake occur:ed on the Sc;utl� P;wh <br /> apprusintately I.100 �cars a��o. <br /> I Sevcral uthcr surfacc faults hacc becn identi�icd in tl�.• Puect Sound rcgion but haec not been ;w�lic�l in <br /> detail to datc. Thc ncarest shallow I�mlt mnpped is the Suuth \�'hidhe� I,land F:wlt. a n�,rth��cst-;nuth�:i,i <br /> vcnding structurc do���n-thro�cn on dic northcast side (USGS OFR ���>-�Si. 199`�I. l�hr f:iult is m;irkcd <br /> � psssine south of thc �:�crcu arca from q hidbep Island through \9ukilt��� <br /> Case:�dia Subductiun '/.uue IIIIL'f�:ll'L` 1?:u�lhy�ur};es. Interface carihyu:�kc> ��cciu rn the h�,undan <br /> bcnveen the Juan de Puca an� \urth �\merican tectonic plates. "fhe C;��c;�di;i tiubductiun Z�mc c�trnJs <br /> � (rom Vuncou�'cr Isl.md lo Northcrn Calilornia. Intcrfacc c;irthqu�kes on thc C�scudi;i Subduction "/_onc <br /> arc anticipated to ha�� duratinns rancine up to d minutc,. <br /> 1 I:videncc of the occurrence uf� lar�c (ma^nihide S to 9+) c.irthquakes occurrims on the Cascadia <br /> Subduction '/_une has recently becn discovercd. Th� last large inieii:�ce earthquake is believed to !iacc <br /> uccwrcd in tlre ycar 170Q I[ is estimated that the average recurrencc inter�'al for interface earthyuakc; u❑ <br /> � the Cascadia Subduction `l_one is ahout -400 to 60U �'ears, ho�vecer, the intercal beh��cen carthyuukcs is <br /> irrcgular. <br /> � Cascadi:i SuLductiun 'Lonc InU•:�pl:�tc IC:�rUiyu:�kcs. C:ucadia Subduction Zone intr�pin[c earthyu;ikcs ' <br /> occur ��iihin the subJuc[ing Juan �e Puca Plate at depihs uf 30 to -!0 miles within western �1'ashineton. <br /> Intr,iplate earthquakes are expected to have Jurations ran^__in!s up to l� scconds and m;��nitudes raneim� <br /> � up to 7.5. The Oiympia 19a9 (ma,_nitude 7.11. thc Seattic 196� lm,ienitude (._), and d�c A'isyu:�ll�� 'U01 <br /> (magnitudc 6.3)arc considcrcd to bu intraplatc c.�rthqu;�kcs. <br /> � Seismic Design � <br />� AVc reconunend �hr fullo�,��ing '_006 hi[crn:nional [3uilJing Code (113C} paramerers fur Site Class. 'I�tnd � <br /> period spcctrul responsc acccleration (S,), l-;ccor.d period spectrnl rcsponsc accelcration (Si), <br /> � Sci,mic Cue�licicn[s I',� and P�. <br /> 2006 IBC Parameter I Recommended Value <br /> ( . . .Site Class __ � . .. � ... . ... <br /> Shon Perwd Spec;ral Response P.cceleratlon,S;(percent g) �I 116 <br /> ___.. qt� � � <br /> 1-Second Period Spectral Response Acceleration,S, (percen[g) _ . ., _ . ._ . <br /> ( . � 8eismicCoefficient F;, .,. . . ��� � <br /> � SeismicCoeflicient F: t�39 � <br /> � <br /> ILiquefaction <br /> Liyucfaction refcrs to [hc cundition where vibr:uiun ur shaking uf the �.tround, usu:illg from e�nhquake <br /> � l��recs, results in the de�rlapment uf escess pore pressures in s:ttunted soils witii s'ubs'eyuent lass of <br /> � <br /> � � �� ,. ;a-rS�-�li�`-il�! PagN J GEOENGINEERS� <br /> %ii' <br /> im:;�.;1 'iS 'illlr� <br />