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- 13 - <br />field investigations would be required to confirm this. For the <br />• purpose of our investigation, we have considered these fault zones to <br />be capable of generating earthe;:akes during the service life of the <br />structure. The most significant .°.ault to seismic exposure at the <br />surface facilities site is the Yampa Fault which is located about <br />21 miles to the north. Tt~e Yatrg~a Fault has a total length of <br />72 miles. It is estimated that a maximum credible earthquake for this <br />fault zone would be a magnitude 6.4. The maximum credible earthquake <br />was calculated based on fault length and magnitude correlations given•~ <br />by Slemmons (1977). The rupture length used in calculating the <br />maximum credible magnitude was one-half the total fault length. Based <br />on magnitude and peak horizontal ground acceleration-attenuation <br />relationships, Donovan and Bernstein (1978), it was determined that a <br /> peak horizontal ground acceleration at the site would be about O.lOg <br />• if a maximum credible earthquake were to occur on the Yanq~a Fault. <br />Design Earthquake: Based on the above evaluation, it appears likely <br />that peak grourd accelerations at the site during the service Life of <br />a project will be within the range oSCfl:+O~~ty~-3tk~. ~ns3sieriag~-th}s° <br />l~evei~t3f~geourd~shak iflg,~-seis+ni~c3esicAxr3tetiaRfc~stt~e2~rea.sY~ou~id <br />l58';;iic.~morcianoe with-the-IInifornr8ui1t1~~pS..-^~°-Seismio=Tnne~2! yip <br />¢valui~tlt`]9 stability-of earth embankments,- a pseudc5=static-seismic? <br />coefficient of 11,.05 should .be_ „~, in_~ankment-stabi'lit-lr-analyses. <br />'tL-its'.coefficie~ esponds,to Seismic Zone=2;~•O:S:=~irmy~CS'rpg~csf <br />~lneers~l977)3' . <br />• <br />