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

Natural Hazards Mitigation PlanCity of Glendale, CaliforniaSection 6 – Earthquakes1975). As with the Long Beach earthquake, legislation was passed in response to the damage causedby the 1971 earthquake. In this case, the building codes were strengthened and the Alquist PrioloSpecial Studies (now Earthquake Fault) Zone) Act was passed in 1972.Whittier Narrows Earthquake of 1987The Whittier Narrows earthquake occurred on October 1, 1987, at 7:42 in the morning, with itsepicenter located approximately 12 miles southwest of Glendale (Hauksson and Jones, 1989). TheM L 5.9 earthquake occurred on a previously unknown, north-dipping concealed thrust fault (blindthrust) now called the Puente Hills fault (Shaw, and Shearer, 1999). The earthquake caused eightfatalities, over 900 injured, and $358 million in property damage. Severe damage was confinedmainly to communities east of Los Angeles and near the epicenter. Areas with high concentrationsof URMs, such as the "Uptown" district of Whittier, the old downtown section of Alhambra, and the"Old Town" section of Pasadena, were severely impacted. Several tilt-up buildings partiallycollapsed, including tilt-up buildings built after 1971, that were built to improved building standardsbut were of irregular configuration, revealing seismic vulnerabilities not previously recognized.Residences that sustained damage usually were constructed of masonry, were not fully anchored tofoundations, or were houses built over garages with large door openings. Many chimneys collapsedand in some cases, fell through roofs. Wood-frame residences, in contrast, sustained relatively littledamage, and no severe structural damage to high-rise structures in downtown Los Angeles wasreported.Pasadena Earthquake of 1988The Pasadena earthquake occurred at 3:38 in the morning on December 3, 1988, directly underneaththe city of Pasadena. The M L 5.0 earthquake occurred on the Raymond fault (Hauksson and Jones,1991), and helped determine that the Raymond fault is a left-lateral strike-slip fault (prior to thisearthquake, the geological community was divided on this issue – the fault forms a well-defined scarpthat many attributed to reverse faulting). This earthquake was also notable because it was followedby an unusually small number of aftershocks, and these were of small size (the largest was only amagnitude 2.4).Sierra Madre Earthquake of 1991The Sierra Madre earthquake occurred on June 28, 1991 at 7:43 in the morning approximately 18miles northeast of Glendale. The M w 5.8 earthquake probably occurred on the Clamshell-SawpitCanyon fault, an offshoot of the Sierra Madre fault zone in the San Gabriel Mountains (Haukson,1994). Because of its depth and moderate size, it caused no surface rupture, but it did triggerrockslides that blocked some of the local mountain roads. Roughly $40 million in property damageoccurred in the San Gabriel Valley; URM buildings were hardest hit, and many brick chimneyscollapsed. Two deaths resulted from this earthquake -- one person was killed in Arcadia, and oneperson in Pasadena died from a heart attack. In all, at least 100 others were injured, though theinjuries were mostly minor.2006 PAGE 6 - 12