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u <br />u <br />n <br />7 <br />n <br />0 <br />C <br />n <br />u <br />relations that equate rupture length with earthquake magnitude. <br />Published data indicate that the maximum credible earthquake on the San Andreas, Hayward, Calaveras, <br />Green Valley -Concord, and the Greenville Faults could produce peak bedrock accelerations of <br />approximately 0.5 g (where g is the acceleration of gravity, equal to 32 feet per second squared). This <br />translates to ground accelerations of approximately 0.3 g in the project region (RGH, August 1993, from <br />Greensfelder, 1974). <br />TABLE 4.4.2 <br />COMPARISON OF INTENSITY AND MAGNITUDE <br />INTENSITYDESCRIPTION <br />. <br />MODIFiEQMERCALLI <br />MAGNITUDE <br />RICHTER <br />Not usually felt. <br />1.67 <br />II <br />Felt by few, upstairs, inside. <br />2.33 <br />III <br />Noticeable indoors as a vibration. <br />3.00 <br />IV <br />Noticeable outdoors by some. <br />3.67 <br />V <br />Felt by everyone, dishes break. <br />4.33 <br />VI <br />Causes fear, damage slight. <br />5.00 <br />VII <br />Damage to poorly built structures. <br />5.67 <br />VIII <br />Damage considerable to ordinary <br />structures. <br />6.1 <br />IX <br />Damage considerable in specially <br />designed structures. <br />6.6 <br />X <br />Ground badly cracked. <br />7.1 <br />XI <br />Few structures standing, bridges <br />destroyed. Broad fissures. <br />8.33 <br />XII <br />Damage total, waves on ground <br />surface, objects thrown into air. <br />8.1 <br />The presumed -inactive Midway Fault is potentially capable of producing the most intense ground <br />accelerations at the site, given that it is located approximately 7 miles from the property. A maximum <br />probable earthquake (the maximum earthquake probable of occurring every 100 years) on the Midway <br />Fault is magnitude 6.5 (Richter). This would produce seismic shaking with peak horizontal ground <br />accelerations estimated at abut 0.52 g (RGH, 1993). <br />The project is located within the Uniform Building Code (UBC) seismic risk zone 4. Table 4.4.3 correlates <br />seismic risk zone with the approximate accelerations, magnitudes, and intensity of an expected <br />earthquake (Lindeburg, 1990). <br />1 ER -93-1 _58- (9-27-93) <br />