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-9- <br />The relatively flat-floored valley bottom of Scullion Gulch is <br />underlain by stream valley alluvium along the present~ay drainage • <br />d~annels, Map Symbol Qal. The stream d~annels are flanked bi' low <br />terraces, Map Symbol Qt, which stand from 2 to 10 feet above the <br />d~annel bottom. The terrace deposits Dover the majority of the valley <br />floor. The stream channel alluvium and the adjacent terrace deposit <br />are interstratified silty sands and sandy silts with some gravel and <br />cobbly layers. The test holes indicate that these deposits in some <br />L-~ <br />places extend to depths of about 20 feet below the valley floor. <br />~~- SEISMIC EXPOSURE <br />The seismic exposure was evaluated based on historic seismicity <br />within 200 miles of the site and the presence of possible capable <br />faults to the southwest and north of the site. <br />Historic Seismicity: The epicenter location for reported earthquakes , <br />within 200 miles of the site between 1880 and the present are shown on <br />Fig. 4. The majority of these earthquakes were small and resulted in <br />no damage even near their epie~ ricers. Eighteen earthquakes caused <br />damage in their epicentral regio::s. These earthquakes are shown by <br />triangles, and a list of damaging earthquakes is shown on Table A. <br />The majority of the damaging earthquakes occurred along the <br />north-trending intermountain belt which runs through central Utah. It <br />is likely that this seismic belt will be the site of future moderate <br />to large earthquakes; however, it is located about 180 miles west of <br />the site, and even if a large earthquake were to occur in this region, <br />ground shaking at the Deserado mine site would not be very strong. A <br /> <br />