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4 ENVIRONMENTAL ANALYSIS <br /> 4.7 GEOLOGY,SOILS,AND SEISM1CrrY <br /> TABLE 4.7-3 <br /> ACTIVE AND POTENTIALLY ACTIVE REGIONAL FAULTS <br /> IN THE VICINITY OF THE PROPOSED RMC PACIFIC VERNALIS QUARRY <br /> v <br /> Approximate <br /> Fault Distances Fault Classification Historical Seismicityb <br /> r <br /> Coast Range/Sierra 4.5 miles southeast Active M6.5, 1983 <br /> Nevada Boundary Zone M6.1, 1985 <br /> M5.5-6.4, 1892 <br /> (data from segments GVOI to <br /> GV 14) <br /> San Joaquin fault 4.5 miles southeast Potentially Active Not Known <br /> Midway-Black Butte 4.1 miles southeast Potentially Active Not Known <br /> fault <br /> Vernalis fault 4.7 miles southeast Potentially Active Pre-Historic Activity(>200 yrs.) <br /> Marsh Creek-Greenville 15 miles southeast Potentially Active M5.6, 1980 <br /> fault (various segments are <br /> considered Active) <br /> -- a Distance from approximate center point of the proposed project site. <br /> b Richter magnitude(M)and year for recent and/or large events. <br /> SOURCES: Spinardi Associates(2002),Jennings(1994),Hart(1997),and Peterson,et al,(1996). <br /> r, <br /> considered very low. Considering this very low probability,seismic hazards related to surface <br /> ground rupture is not discussed farther in this document. <br /> Ground Motion <br /> Strong ground motion is described as motion of sufficient strength to affect people and their <br /> environment or any ground movement recorded on a strong motion instrument or seismograph. <br /> The common way to describe ground motion during an earthquake is with the motion parameters <br /> 4r of acceleration and velocity in addition to the duration of the shaking. A common measure of <br /> ground motion is the peak ground acceleration (PGA), which is the largest value of horizontal <br /> acceleration obtained from a seismograph. PGA is expressed as the percentage of the <br /> acceleration due to gravity(g), which is approximately 980 centimeters per second squared. In <br /> terms of automobile accelerations, one "g"of acceleration is a rate of increase in speed equivalent <br /> r to a car traveling 328 feet from rest in 4.5 seconds. For comparison purposes,the maximum peak <br /> acceleration value recorded during the Loma Prieta earthquake was in the vicinity of the <br /> epicenter, near Santa Cruz, at 0.64 g. The highest value measured in the East Bay was 0.29 g, <br /> recorded at the Oakland Wharf near the Naval Supply Center. Soils at the wharf are artificial fill <br /> over Bay Mud. The lowest values recorded were 0.06 g in the bedrock on Yerba Buena Island. <br /> v <br /> RMC Pacific VemaRs Quany Mining std Reclatmtion Project 4.7-7 FSA/203015 <br /> Ad. U,e[haft EIR Match 2004 <br />