2024-018 - Emergency Operations Plan

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City of Santa Ana Emergency Operations Plan Part I Basic Plan Yet the San Andreas is only one of numerous known active faults that crisscross Southern California. A fault is considered active if it has ruptured within the last 11,000 years and potentially active if it has ruptured in the last 1.8 million years. Large faults that would affect the Orange County area include the San Andreas, Newport - Inglewood, Los Alamitos, Whittier, Elsinore, Chino and San Jacinto Faults. Smaller Orange County -area faults include the Norwalk Fault, the El Modena and Peralta Hills Faults, as well as the newly studied San Joaquin Hills and Puente Hills Faults. Beyond these known faults, there are potentially a number of "blind" faults, faults that have not yet been discovered or mapped, underlying the surface of Southern California. The Whittier Narrows Earthquake in October 1987 and the Northridge Earthquake in January 1994 occurred on blind faults. Figure 34 Orange County Earthquake Fault Zones N_.0 o u Orange County ` P.utt Zones r,. ,mm cmxnv¢u I••• 2p tG swumx � J, rA,H 'ty� q as A � p O� 9 T oC 0 c _.._..._ Legentl e�K.mmien e�®® e � Notes on Figure 34: The fault touching the right margin of the map is the Elsinore Fault but is incorrectly labeled the Whittier Fault. The Whittier Fault lies at the top center where it is correctly labeled. The San Joaquin Hills Fault does not appear on this map but runs along the 405 Freeway south of the City border. Although the most famous of the faults, the San Andreas, is capable of producing an earthquake with a magnitude of 8.0 or more on the Richter scale, some of the "lesser" faults have the potential to inflict greater damage on the urban core of Orange County. Seismologists believe that a 6.0 earthquake on the Newport -Inglewood would result 34