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<br />a <br />t',..... <br /> <br />6 <br /> <br />~ <br />'-- <br /> <br />(, <br /> <br />;.-) <br />(-") <br /> <br />f---" . 3. <br />- <br /> <br />SEISMICITY <br /> <br />(J <br /> <br />The Colorado Geological Survey (Kirkham and Rogers, 1981) places <br />the site within the Colorado Plateau seismotectonic province. <br />Earthquake potential within this province has been termed <br />moderate (CGS, 1982) with the estimated maximum credible <br />earthquake having a Richter scale magnitude of 5.5 to 6.5. <br /> <br />Earthquake epicenters for the region within a 200 mile radius of <br />the site were obained from the NOAA Environmental Data and <br />Information Service in Boulder, Colorado. Figure 4 is a map <br />showing the epicenter and the magnitude of each earthquake <br />reported between 1853 and May 1981. ~he data associated with <br />each point plotted on Figure 4 is presented-in Appendix D. As <br />shown on Figure 4, three earthquakes having modified Mercalli <br />magnitudes between III and V are located within 30 miles of the <br />site. Data regarding these earthquakes are as follows: <br /> <br /> Modified <br /> Distance Mercalli <br /> Time Effect From Site Magnitude <br /> Aug. .1, 1963 @ 5:00 a.m. Not reported 6 miles III to IV <br /> Nov. 12, 1971 @ 9:30 a.m. Felt 29 miles IV to V <br />( Jan. 30, 1975 @ 2:48 p.m. Felt 20 miles IV to V ( <br /> <br />Based on this data, it can be inferred that the maximum peak <br />ground acceleration between 0.05 g and 0.1 g could be expected. <br />The lower value of this range agrees with the maximum expected <br />rock acceleration presented by Algermissen and Perkins (1976) for <br />this area. <br /> <br />c <br /> <br />c <br />