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Central Valley Coast Range Fault The North County Landfill site is located east of the Central Valley Coast Range Fault (CRCV) which is a subject of ongoing controversy for seismic hazard. The CRCV fault is comprised of a series of blind thrust faults. That is, there is no surface trace of the fault. Therefore, its location is uncertain. The activity rate of this fault is also highly uncertain. The location and existence of this fault in the Sacramento Delta region is highly uncertain. For this project, we have assumed that the CRCV fault exists as given in the USGS national hazard maps. The CRCV extends about 600 km along the western edge of the Central Valley in central and northern California (Wong et al,1988), but the faulting is discontinuous. Most of the segments lengths are 25 to 45 km with a maximum segment length of about 55 km. The closest segment to the North County Landfill site is the Great Valley 6 (GV6) fault segment which has a length of 45 km, downdip width of 10 km, and a slip rate of 1.5 mm/yr (Cao et al., 2003). This buried reverse fault is dipping to the west at an angle of 15 degrees and the closest distance to the fault is approximately 54 km. The frequency of occurrence of earthquakes on the Central Valley Coast Range fault is isestimated using the fault parameters listed in Table 1 and a characteristic magnitude recurrence model (Youngs and Coppersmith, 1985). The 100 -year probability of at least one earthquake of magnitude M or larger is shown in Figure 1. Based on the long term slip -rate, there is about a 1/3 chance of having a magnitude 5.1 earthquake or larger on the Great Valley 6 segment in the next 100 years. The seismic source of the April 19, 1892 Winters Earthquake, M=6.4 (Toppozada, 1981) is not well constrained. It may be associated with the northern extension of the CRCV fault. For this study, I have assumed that the Winters Earthquake occurred along the CRCV fault. This is a conservative assumption, but I think that it is reasonable given the current uncertainty about the CRCV fault. Using the CDMG definition, the MPE for this fault is defined by the historical earthquake. The recommended MPE is a magnitude 6.4 at a distance of 54 km. Greenville -Marsh Creek -Arroyo Fault The Greenville fault is part of the Greenville -Marsh Creek -Arroyo fault system has primarily strike -slip motions and extends for a total length of 51 km. The Greenville-