Glendale (PDF) - Hazard Mitigation Web Portal - State of California

Natural Hazards Mitigation PlanCity of Glendale, CaliforniaSection 6 – EarthquakesHAZUS Scenario Earthquakes for the Glendale AreaFive specific scenario earthquakes were modeled using the HAZUS loss estimation softwareavailable from FEMA: earthquakes on the San Andreas, Sierra Madre, Verdugo, Raymond andHollywood faults (see Table 6-5).Fault Source MagnitudeSan Andreas -Mojave SegmentTable 6-5: HAZUS Scenario Earthquakes for the City of Glendale7.1DescriptionA large earthquake that ruptures the Mojave segment of the SanAndreas fault is modeled because of its high probability of occurrence,even though the epicenter would not be too close to the City.Sierra Madre 7.2Verdugo 6.7Raymond 6.5Hollywood 6.4Likely worst-case scenario for the Glendale area. The 7.2 magnitudeearthquake modeled is at the lower range of the size of earthquakes thatresearchers now believe this fault is capable of generating.Possible worst-case scenario for Glendale. Although this earthquake isnot as large as the one estimated on the Sierra Madre fault, this faultextends through an extensively developed area, and therefore has thepotential to cause significant damage to buildings and infrastructure.Maximum magnitude earthquake on the Raymond fault. This fault nearthe southern portion of the City could cause significant damage in thesouthern and eastern portions of Glendale, and in the San Rafael Hills.Maximum magnitude earthquake on the Hollywood fault would causeextensive damage in Hollywood, West Hollywood, and in thesouthwestern portion of Glendale. This fault could break together withthe Santa Monica faults, generating a stronger, more damagingearthquake than the one presented herein.Four of the five earthquake scenarios modeled for this study are discussed in the followingsections. An earthquake on the San Andreas fault is discussed because it has the highestprobability of occurring in the not too distant future, even though the loses expected from thisearthquake are not the worst possible for Glendale. An earthquake on the San Andreas fault hastraditionally been considered the “Big One,” the implication being that an earthquake on thisfault would be devastating to southern California. However, there are several other seismicsources that, given their location closer to the Los Angeles metropolitan area, have the potentialto be more devastating to the region, even if the causative earthquake is smaller in magnitudethan an earthquake on the San Andreas fault. The 7.1 magnitude San Andreas earthquakemodeled for this study would result from the rupture of the Mojave segment of the fault. Thissegment is thought to have more than a 40 percent probability of rupturing in the next 30years. A larger-magnitude earthquake on the San Andreas fault would occur if more than onesegment of the fault ruptures at the same time. If all three southern segments of the SanAndreas fault break together, an earthquake of at least magnitude 7.8 would result.The Sierra Madre and Verdugo scenarios are also presented here because both of these faultshave the potential to cause significant damage in the City. As discussed in Section 1.5.5, theSierra Madre fault appears to have last ruptured more than 8,000 years ago, and may be nearthe end of its strain accumulation cycle. Given that recent studies suggest that the Sierra Madre2006 PAGE 6 - 40