Item 26 - Updated Hazard Mitigation Plan

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Hazard Mitigation Plan | 2022 Earthquake Hazards - 51 - Table: Historic Earthquakes Affecting Communities Near Orange County (Source: USGS) (Date Earthquake Damage March 29, 2014 La Habra, M5.1 On March 29, 2014, at 9:09pm, an earthquake hit one mile away from La Habra. It was followed by 30 aftershocks. The quake resulted in roughly 2,000 people without power, but the community suffered minimal damage. July 29, 2008 Chino Hills, M5.4 On Tuesday, July 29, 2008, at 11:42 a.m. Pacific Daylight Time, a magnitude 5.4 earthquake rumbled the East Los Angeles area of California. The epicenter of the quake was about 9 miles beneath the Chino Hills. According to reports from the U.S. Geological Survey (USGS), the quake and several aftershocks caused strong shaking from the Chino Basin in the north to the Los Angeles basin in the southwest. Some shaking was felt as far away as Las Vegas, Nevada, and Yuma, Arizona. March 11, 1933 Long Beach, M6.4 In the early evening hours on March 10, 1933, the treacherous Newport-Inglewood fault ruptured, jolting the local citizenry just as the evening meals were being prepared. The Magnitude 6.4 earthquake caused extensive damage (approximately $50 million in 1933 dollars) throughout the City of Long Beach and surrounding communities. Damage was most significant to poorly designed and unreinforced brick structures. Sadly, the earthquake caused 120 fatalities. Within a few seconds, 120 schools in and around the Long Beach area were damaged, of which 70 were destroyed. Experts concluded that if children and their teachers were in school at the time of the earthquake, casualties would have been in the thousands. Q&A | ELEMENT B: HAZARD IDENTIFICATION AND RISK ASSESSMENT | B1a. Q: Does the plan include a general description of all natural hazards that can affect each jurisdiction? (Requirement §201.6(c)(2)(i)) A: See Local Conditions below. Q&A | ELEMENT B: HAZARD IDENTIFICATION AND RISK ASSESSMENT | B3b. Q: Is there a description of each identified hazard’s overall vulnerability (structures, systems, populations, or other community assets defined by the community that are identified as being susceptible to damage and loss from hazard events) for each jurisdiction? (Requirement §201.6(c)(2)(ii)) A: See Local Conditions below. Local Conditions According to the Orange County General Plan, Safety Element (2013), potentially hazardous, active fault zones run along the coastal and inland edges of the County. The best known of the faults is the Newport-Inglewood Fault, which angles from offshore near Dana Point, inland through what is now the City of Newport Beach, on into Los Angeles County through the cities of Long Beach and Torrance. This fault zone produced the catastrophic 1933 Long Beach earthquake with a Richter scale magnitude of 6.3. It is believed this fault is capable of generating a maximum 7.5 magnitude earthquake. Due to the proximity of active and potentially active faults in and around Orange County and its degree of urbanization, the risk of structural damage and loss of life due to ground shaking is considerable. The risk of secondary hazards is also great. According to various geologic experts, much of Orange County is highly susceptible to slope failure (activated by ground shaking), lurching and displacement. Another secondary hazard of particular concern to some portions of Orange County is that of liquefaction.