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4.Environmental Analysis — project site.4 This fault is also known as the Coast Range/Sierra Nevada boundary zone _ (CRSNBZ) which separates the Coast Range province and the Central Valley. Seismicity of the CRSNBZ consists of several historic moderate-magnitude earthquakes on various segments of faults in the zone. Notable earthquakes include the Coalinga earthquake of 1983 (moment magnitude 6.5; MMI VIII),the Avenal blind thrust earthquakes of 1985 (moment magnitude 6.1; MMI VI),and the Vacaville-Winters earthquake sequence of 1892(moment magnitudes 6.4, 6.2, and 5.5;MMI VIII-DO. Other active and potentially active faults and fault systems within — approximately 15 miles of the project site include the San Joaquin fault,the Midway-Black Butte fault, the Vernalis fault,and the Marsh Creek-Greenville fault. Historic moderate to large earthquake events on more distant faults, such as the Mount Diablo thrust fault, the Calaveras — fault, the Hayward-Rodgers Creek fault,the Concord-Green Valley fault, and the San Andreas fault,have also produced MM intensities of VI to VII in the vicinity of the project site. — Table 4.7-3 lists these fault systems,the dates of their most recent major historic earthquakes, and the estimated maximum moment magnitude of a characteristic event. Figure 4.7-1 shows the faults and their vicinity to the project site. — TABLE 4.7-3 ACTIVE AND POTENTIALLY ACTIVE REGIONAL FAULTS IN THE VICINITY OF THE PROPOSED RMC PACIFIC VERNALIS QUARRY — Approximate Fault Distances Fault Classification Historical Seismicityb _ Coast Range/Sierra Nevada 4.5 miles southeast Active M6.5, 1983 Boundary Zone M6.1, 1985 M5.5-6-4, 1892 (data from segments GV01 to GV14) San Joaquin fault 4.5 miles southeast Potentially Active Not Known Midway-Black Butte fault 4.1 miles southeast Potentially Active Not Known Vernalis fault 4.7 miles southeast Potentially Active Prehistoric Activity(>200 years) Marsh Creek-Greenville fault 15 miles southeast Potentially Active M5.6, 1980 (various segments are considered Active) — a Distance from approximate center point of the proposed project site. b Richter magnitude(M)and year for recent and/or large events. SOURCES: Spinardi Associates(2002),Jennings(1994),Han(1997),and Petersen,at al.,(1996). — 4 An active fault is defined by the State of California as a fault that has had surface displacement within Holocene time(approximately the last 10,000 years).A potentially active fault is defined as a fault that has shown evidence of surface displacement during the Quaternary(last 1.6 million years),unless direct geologic evidence demonstrates inactivity for all of the Holocene or longer.This definition does not,of course,mean that faults lacking evidence of surface displacement are necessarily inactive.Sufficiently active is also used to describe a fault if there is some evidence that Holocene displacement occurred on one or more of its segments or branches(Hart, 1997). RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.7-6 ESA/203015 Draft Environmental Impact Report May 2006