Northridge, California Earthquake, January 17, 1994, Set 1
Parking structure on the campus of California State University. The bowed columns are of reinforced concrete. The structure has precast moment- resisting-concrete frames on the exterior and a precast concrete interior designed for vertical loads. The inside of the structure failed, and with each aftershock the outside collapsed slowly toward the inside until finally the west side failed totally. The reinforced concrete columns were extremely bent.
At 4:31 A.M. (Local time) on Monday, January 17, 1994, a magnitude 6.8 earthquake twenty miles west northwest of downtown Los Angeles awoke nearly everyone in southern California. Damage was most extensive in the San Fernando Valley, the Simi Valley, and in the northern part of the Los Angeles Basin. This slide set depicts the damage in Northridge-the epicentral area. Photos show damage to a shopping center, parking garages, and the interior and exterior of apartment buildings. After the earthquake, a total of 24,000 dwellings were vacated. The death toll from the quake was 57. The total cost of the earthquake is estimated to be at least $10 billion. The earthquake epicenter was at the intersection of Wilbur Avenue and Arminta Street in Northridge, a college community 20 miles northwest of downtown Los Angeles. The main shock occurred on a shallowly-dipping, previously-unknown thrust fault beneath the suburb of Northridge. The rupture begin at about twelve miles depth and traveled upward and northward, spreading both eastward and westward. The focal mechanism of the main shock from both first motions and teleseisms shows a N 60 degrees west striking and 35 degrees to 45 degrees south dipping plane. Rock on southside of the fault surged upward and over the rock on the north side. As a result of the quake, the San Fernando Valley is slightly narrower and themountains just north of the valley are slightly higher. The Northridge Fashion Mall was extensively damaged by the earthquake. Bullocks Department Store in the mall collapsed. One parking structurecollapsed into a pile about twenty feet high. Other department stores and parking structures were also damaged. Windows were shattered throughout the mall. Severe damage and partial collapses were seen also in other, smaller, shopping centers near the epicenter. Northridge Meadows Apartment Complex - Not far from the Northridge Fashion Mall sixteen people were killed when the 164-unit Northridge Meadows Apartment collapsed. There was an area of several square miles in Northridge where there was intense damage to apartments built in the 1960's and early 1970's, prior to the latestrevisions in the building codes for multi-family housing. Many of these apartment buildings had "soft" first stories. California State University Campus - Most of the sixty buildings on the campus performed well and there were no injuries or deaths on the campus. One parking structure collapsed and three buildings were severely damaged and were unrepairable. Fifteen to twenty buildings will require structural repairs and retrofitting to meet code. Inside the buildings the contents were severely disturbed. Freight Train Derailed - A sixty-four car Southern Pacific freight train carrying hazardous material was derailed between the communities of Chatsworth and Northridge. Sulfuric acid was released from one of the sixteen tank cars carrying the substance. Two thousand gallons of diesel fuel spilled from the locomotive. Northridge Community Center Hospital - At Northridge Community Center, located near the epicenter, patients in wheelchairs were rushed outside. There was no water, no power, and no phones. At the same time the center was deluged with requests for treatment from people suffering injuries in the earthquake. The Northridge earthquake is significant since it is the most expensive earthquake and one of the most expensive natural disasters in United States history yet it occurred on a previously unknown fault.
Metadata Last Modified: 2011-04-06
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