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D.3 Earthquake This Incident -Specific Annex provides specific details to support effective response to and recovery from an earthquake emergency. It is intended to supplement the information and instructions in the Basic Plan. Situation and Assumptions Earthquakes may occur at any time and with no warming. They may be caused by any number of faults in the region, including the San Andreas and Hayward faults, both of which have a reasonable chance of causing a major earthquake. A number of other faults may also cause earthquakes, although these faults have a lower chance of causing an earthquake and/or would be more likely to cause smaller (but still potentially damaging) earthquake events. A significant earthquake event could cause major damage throughout all of Redwood City. Older unretrofitted structures have a greater risk of being damaged or destroyed, although a strong enough earthquake may damage even newer, well-built structures. Areas built on fill, such as those along the shore of the San Francisco Bay are also at risk of liquefaction, an earthquake -induced phenomenon that could cause buildings and other structures to collapse. Any major earthquake would almost certainly be followed by a series of other earthquakes called aftershocks. Aftershocks are smaller than the main shock but may still be strong enough to cause damage. Aftershocks may persist for hours or days following the main shock. Earthquakes are a regional event. An incident strong enough to cause substantial damage to Redwood City would almost certainly have significant impacts throughout San Mateo County and parts of or the entire San Francisco Bay Area region. An earthquake event may cause one or more of the following direct impacts on Redwood City: • Significant structural damage or total collapse of buildings and other structures. • Downed trees. • Collapsed power lines and communication towers. • Broken roadways and rails, causing interruptions to transportation systems. • Ruptured water and wastewater pipes, interrupting service and potentially causing flooding or environmental health hazards. • Earthquake -induced landslides in hilly areas. • Releases of hazardous materials. • Road congestion from traffic light outages. • Fires from natural gas leaks or damaged electrical equipment. • Tsunami or seiche events (see the tsunami incident -specific annex for details). • Widespread and significant injuries or death to community members. A substantial earthquake event would likely require significant mobilization of Redwood City resources as well as extensive coordination with external agencies. Search and rescue and shelter activities would D-13