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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 146 playa and terrace deposits that are both consolidated and semi-consolidated throughout the Central Valley. In Alameda County, we can expect the soil to both have characteristics of quaternary deposits listed above and Mesozoic sedimentary and metasedimentary rocks, specifically, upper cretaceous sandstone, shale and conglomerate rock material (CDC 2010a). Based on available web soil surveys and the vast distribution of the Impact Areas we can generalize that the surface soils will likely consist of alternating layers of silts, clays, loams and sand with some gravels which are underlain by either sedimentary rock or quaternary deposits (USDA 2019). An “active” fault is one that shows displacement within the last 11,000 years and, therefore, is considered more likely to generate a future earthquake than a fault that shows no sign of recent rupture. The California Geologic Survey has mapped various active and inactive faults in the region. There are several active faults located within or surrounding all six counties overlapping the Study Area: Antioch, Calaveras, Cleveland Hills, Concord, Greenville-Marsh Creek, Hayward, San Andreas, San Joaquin and Sierra Nevada Faults. There is a generally low to moderate liquefaction potential at and around several Impact Areas. 3.7.2 Discussion a) Would the project directly or indirectly cause 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 California Geological Survey Special Publication 42.) Less than Significant Impact. As with the entire San Francisco Bay Area, the southern Impact Areas are subject to strong ground motion resulting from earthquakes on nearby faults. No Impact Areas are within a currently designated Alquist-Priolo Earthquake Fault Zone (CDC 2015a). Additionally, the footprint of each Impact Area is small and temporary. Additionally, the limited nature of the Proposed Project minimizes potential adverse impacts related to ruptures of known earthquake faults. While there would be a less than significant impact, implementation of Mitigation Measures MM AES-1 and MM AGR-1 would further avoid, minimize and/or reduce the potential for impacts. ii) Strong seismic ground shaking? Less than Significant Impact. The Impact Areas are in a seismically active region that has historically been affected by strong seismic ground shaking. Ground shaking is a general term referring to all aspects of motion of the earth’s surface resulting from an earthquake and is normally the major cause of damage in