Res21 16010 final - Laserfiche WebLink

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Earthquake San Mateo County and participating cities strictly enforce all seismic building codes and design standards to prevent loss of life and property caused by earthquake. Municipal planning partners are encouraged to establish general plans with policies directing land use and dealing with issues of seismic safety. These plans provide the capability at the local municipal level to protect future development from the impacts of earthquakes. Public education, cooperation with the development community, and individual preparedness are essential as the planning area welcomes new community members and businesses. 10.6 SCENARIO Based on history and geology, the planning area will be frequently impacted by earthquakes. The worst-case scenario is a higher-magnitude event (7.5 or higher) with an epicenter within 50 miles of the county. The San Andreas fault scenario modeled for this risk assessment would mimic this scenario. Earthquakes of this magnitude or higher could lead to massive structural failure of property on soils prone to liquefaction. Building and road foundations would lose load-bearing strength. Injuries could occur from debris, such as parapets and chimneys that could topple or be shaken loose and fall on those walking or driving below. Levees and revetments built on these poor soils would likely fail, representing a loss of critical facilities. An earthquake event of this magnitude located off the coast could cause a significant local tsunami that would further damage structures and jeopardize lives. An earthquake may also cause minor landslides along unstable slopes, which put at risk major roads and highways that act as sole evacuation routes. This would be even more likely if the earthquake occurred during the winter or early spring. 10.7 ISSUES Important issues associated with an earthquake include the following:  More information is needed on the exposure and performance of soft-story construction within the planning area.  It is estimated that over 70 percent of the planning area’s building stock was built prior to 1975, when seismic provisions became uniformly applied through building code applications. Many structures may need seismic retrofits in order to withstand a moderate earthquake. Residential retrofit programs, such as Earthquake Brace+Bolt, may be able to assist in the costs of these efforts.  Based on the modeling of critical facility performance performed for this plan, a high number of facilities in the planning area are expected to suffer complete or extensive damage from scenario events. These facilities are prime targets for structural retrofits.  Critical facility owner should be encouraged to create or enhance Continuity of Operations Plans using the information on risk and vulnerability contained in this plan.  Geotechnical standards should be established that take into account the probable impacts from earthquakes in the design and construction of new or enhanced facilities.  There are a large number of earthen dams within the planning area. Dam failure warning and evacuation plans and procedures should be reviewed and updated to reflect the dams’ risk potential associated with earthquake activity in the region. The County levees should also be included in any assessments for earthquake risk.  Earthquakes could trigger other natural hazard events such as dam failures, flood, fire, and landslides, which could severely damage the County. 10-29