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magnitude. For this study, relationships published in Slemmons (1977) <br />and Slemmons and Chung (1982) were applied to the previously identi- <br />fied faults. The resulting MCE estimates are summarized on Table C-1. <br />For the faults of the Sierran Foothills fault system (i.e., Bear <br />Mountains and Melones fault zones), the MCE estimates are in agreement <br />with those of Borchardt (1972) and Woodward -Clyde Consultants (1977), <br />presented previously. While MCE estimates for the other faults listed <br />in Table C-1 are slightly higher, they are at greater distances from <br />the site and, therefore, are unlikely to produce design ground accel- <br />erations at the site (see Table C-1). <br />Because the MPE is defined as the maximum earthquake that is likely to <br />occur during a 100 -year interval, both the size of potential earth- <br />quakes and the average frequency at which they occur (i.e., mean <br />recurrence interval) must be considered in developing MPE estimates. <br />The frequency of earthquake recurrence may be approximated from the <br />historic earthquake record and/or detailed geologic studies along <br />individual fault traces that clearly offset dateable geologic units. <br />For the Sierran Foothills fault system, the historic earthquake record <br />is of insufficient length to estimate the recurrence interval for <br />significant earthquakes. The work of previous researchers has result- <br />ed in estimates of recurrence intervals for faults in the Sierran <br />Foothills fault system ranging from 100 to greater than 10,000 years <br />(Hart, et al., 1984). These values compare favorably with recurrence <br />intervals estimated using relationships of earthquake magnitude and <br />fault slip rates, which are published in Slemmons and Chung (1982). <br />Available slip -rate data are limited (Clark, et al., 1984) and suggest <br />that the MCEs for the fault system (magnitude 6.5) are characterized <br />by long recurrence intervals ranging from 6,000 to 80,000 years. This <br />suggests that the probability of having the MCE on the Sierran Foot- <br />hills fault system in the next 100 years is relatively low. <br />To develop an MPE estimate for the Bear Mountains and Melones fault <br />zones, a probabilistic analysis was conducted using relationships <br />developed by Kiremidjian and Shaw and published in Shaw (1982). In <br />