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MOUNTAIN HOUSE NEIGHBORHOODS K AND L INITIAL STUDY 5.ENVIRONMENTAL CHECKLIST B. GEOLOGY AND SOILS Significant Impacts Identified in 1994 MEIR The 1994 MEIR identified a significant and potentially significant geology and soils impact of the Master Plan, as follows: 1) Strong ground shaking during an earthquake could cause structural damage and injuries to residents of the proposed project. Findings Related to Significant Impacts Identified in 1994 MEIR The Master Plan required the preparation and distribution of a Community Earthquake Preparedness Plan to reduce project impacts associated with strong ground shaking during an earthquake(Policy 6.8.3a). Structures will be 1 designed and constructed in accordance with recommendations listed in the geotechnical engineering study for each neighborhood. Despite mitigation efforts,this remains a significant, unavoidable impact and findings related to this fact were adopted for the 1994 MEIR certification. Discussion Regarding Neighborhoods K and L Fj a) Would the project expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: i) Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42. No Alquist-Priolo Earthquake Fault Zones have been mapped in San Joaquin County. No active faults have been identified within the Mountain House l community. Therefore, surface ground rupture from faulting is not considered a - significant hazard at the project site. No impact related to fault rupture is expected to occur as a result of project development. No mitigation measures are necessary. ii) Strong seismic ground shaking? San Joaquin Valley is a seismically active region of California. Strong ground shaking resulting from earthquakes along nearby or distant faults represents the greatest seismic hazard at the Mountain House community. Active and potentially active faults in the vicinity of the project site are listed in Table 5.6-1. Fil The intensity of ground shaking at any particular site is a function of many factors, including 1)earthquake magnitude,2)the site's distance from the epicenter, 3)the duration of strong ground motion,4)local geologic conditions (soil characteristics and topography),and 5) depth to bedrock. As indicated in Table 5.6-1,the project site may be susceptible to earthquake magnitudes of 6.2 P or higher. During an earthquake, structural damage at the project site may include damage to buildings and infrastructure(roads, bridges, utilities). {ann 1I 5-77 ! 1 ,