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MOUNTAIN HOUSE PROPOSED MACHADO TENTATIVE MAP 4. ENVIRONMENTAL CHECKLIST 4.6 GEOLOGY AND Sons MITIGATION MEASURES IDENTIFIED IN 2005 SPIIIEIR The Initial Study for the 2005 SPIIIEIR noted that the significance of potential impact associated with seismic ground shaking would be reduced,but not entirely eliminated,by the following: 1. Preparation of an Earthquake Preparedness Plan that is being implemented by the MHCSD. 2. Regulations governing design and construction of schools and police, fire and — emergency services buildings. 3. Uniform Building Code requirements for construction of residential,commercial and industrial buildings. DISCUSSION REGARDING PROPOSED PROJECT a) 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 Community site(CDMG, 2000). Therefore, surface fault rupture is not considered a hazard at the project site,and no impact related to fault rupture would occur as a result of project development. Mitigation Measures No mitigation measures are required. ii) Strong seismic ground shaking? San Joaquin Valley is a seismically active region of California. Strong, seismically-induced — ground shaking resulting from earthquakes along nearby or distant faults represents the greatest seismic hazard at the Mountain House Community. The intensity of ground shaking at any particular location is a function of many factors including: (1) earthquake magnitude, — (2)distance from the epicenter of the earthquake, (3)the duration of strong ground motion, (4)local geologic conditions (soil characteristics and topography), and(5) depth to bedrock. During an earthquake, structural damage at the project site may include damage to buildings and infrastructure(i.e.,roads,bridges, water tanks, etc.). Active and potentially active faults in the vicinity of the project site are summarized in the — Initial Study of the SPIIIEIR(EDAW, 2005b, Appendix D,Table 4-1). It is estimated that 16 earthquakes of magnitude 6.0 or greater have occurred within 62 miles of the project site between 1800 and 1999. As indicated, regionally active faults are capable of producing — 4-28