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330 Land Company, LLC Arroyo Lago 9785.004.001 Design-Level Geotechnical Report Page | 10 April 16, 2024 Latest Revision October 31, 2025 3.3 SEISMIC HAZARDS Potential seismic hazards resulting from a nearby moderate to major earthquake can generally be classified as primary and secondary. The primary effect is ground rupture, also called surface faulting. The common secondary seismic hazards include ground shaking, liquefaction, and lateral spreading. The following sections present a discussion of these hazards as they apply to the site. Based on topographic and lithologic data, the risk of regional subsidence or uplift is considered low to negligible at the site. 3.3.1 Ground Rupture Since there are no known active faults crossing the property and the site is not located within an Earthquake Fault Special Study Zone, it is our opinion that ground rupture is unlikely at the subject property. 3.3.2 Ground Shaking An earthquake of moderate to high magnitude generated within the San Francisco Bay region could cause considerable ground shaking at the site, similar to that which has occurred in the past. To mitigate the shaking effects, structures should be designed using sound engineering judgment and the current California Building Code (CBC) requirements, as a minimum. Structures under the CBC should be able to: (1) resist minor earthquakes without damage, (2) resist moderate earthquakes without structural damage but with some non-structural damage, and (3) resist major earthquakes without collapse but with some structural and non -structural damage. Conformance to the current building code does not constitute any kind of guarantee that significant structural damage would not occur in the event of a maximum magnitude earthquake; however, it is reasonable to expect that a well-designed and well-constructed structure will not collapse or cause loss of life in a major earthquake (SEAOC, 1996). 3.3.3 Liquefaction The site is not located within a potentially liquefiable zone based on the Seismic Hazards Zone map for the Livermore Quadrangle by the California Geological Survey (CGS, 2008); however, according to mapping prepared by the Association of Bay Area Governments (ABAG, 2001), the site is identified as moderately susceptible to liquefaction. We assessed liquefaction potential at the site by reviewing data from our field exploration logs. As previously discussed, the subsurface soil consists of stiff to hard lean clay to the end of the borings. Historically high groundwater resides at roughly 60 feet bgs. We analyzed the liquefaction susceptibility of the subsurface material based on the borings using the methods proposed by Youd and Idriss in 2001, Seed et al. in 2003, and Idriss and Boulanger in 2008. We considered a maximum considered earthquake (MCEG) peak ground acceleration (PGAM) value of 0.67 g based on the 2025 California Building Code with an earthquake magnitude of 7.0 based on a 2-percent in 50 years disaggregation and a groundwater level of 50 feet below existing grade. Based on the soil type, boring analysis, and the depth to hydrostatic groundwater, the material is not susceptible to liquefaction triggering. Therefore, we consider the potential for liquefaction of the site soil to be low.