Alquist that required earthquake zones to be mapped and set new design standards for hospitals. Within two years, the California Legislature responded with laws championed by state Sen. Francis Dam, to tighten its standards to include liquefaction, resulting in dams across the state being retrofitted. The near catastrophe led the California Division of Safety of Dams, an agency created after the 1928 failure of the St. It galvanized both the state and the federal government.” “Had the shaking gone on for maybe another five seconds or 10, it could have been horrific. The water level had been lowered 10 feet in 1967 after an evaluation had raised doubt about its stability. “This was a big one because people started to realize you could have killed 100,000 people if that dam had cut loose,” said acting state geologist Steve Bohlen. That was the recognition of that earthquake, ‘Oh, we shouldn’t be building on top of faults that can rupture the surface.’”įor the seismic community, the near debacle of the Lower Van Norman Dam, causing no loss of life but forcing the evacuation of 80,000 people, was the most frightening lesson. “It would go through people’s lawns, it would go through homes,” said Tim Dawson, engineering geologist with the California Geological Survey. 9, 1971, woke California up to a largely unfamiliar danger. The Times recalls how the quake that rumbled through L.A.
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They proved helpless when the fault rupture reached the surface, a phenomenon that had not previously occurred in an urban earthquake.Ĭalifornia Full Coverage: 50 years after the Sylmar earthquake
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“The code would essentially produce nonductile concrete buildings.”Īnother revelation was the damage to single-family homes, at the time thought to be resilient enough to ride out moderate quakes. “You had to have ductility” - the ability to stretch. “We as an engineering community learned from that, that just having strength was not enough,” said Jonathan Stewart, professor of civil and environmental engineering at UCLA. The hospital buildings and the freeways, all made of concrete, proved unable to roll with the earthquake’s punches. “There were some structures that people thought were safe that turned out not to be,” Hough said. No less shocking was the collapse of the soaring, nearly completed overpass from the new Antelope Valley Freeway (Highway 14) to the Golden State Freeway (Interstate 5) in Newhall Pass and portions of the Foothill Freeway (I-210) interchange, where two men in a pickup were killed. Elevator towers tumbled, and the second floor of the 50-bed psychiatric unit collapsed onto the first. Less costly in lives, yet more startling to engineers and scientists, was the partial collapse of the 4-month-old Olive View Medical Center. The Sylmar quake was one of the worst in modern Los Angeles history, killing 64 people, injuring 2,543 and causing $553 million in damage. not only woke up the city but fixated the nation’s budding seismic community as none had before.Ĭalifornia ‘Abject terror gripped me’: Terrifying memories of the Sylmar earthquake of 1971 The 6.6 magnitude earthquake that struck the northeast San Fernando Valley seconds after 6 a.m. The modern era of earthquake awareness and preparedness is deeply rooted in Sylmar.īefore then, earthquakes were either removed in time - 1906 in San Francisco, 1933 in Long Beach - or physically distant -1964 in Anchorage. The quake might not have been the Big One, but it still managed to wake California up to a danger that was largely unrecognized. That the dam survived has rendered those questions a subject for scientific inquiry rather than the annals of catastrophe.īut what might have been remains part of the mystique that sustains the Sylmar earthquake - formally, the San Fernando earthquake - as the keystone in the long arc of seismic knowledge and the practice of earthquake safety.
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Was it the number of feet of earthen wall that remained? Was it the duration of the quake, since a few more seconds might have shaken loose the rest of the dam face, unleashing a torrent on tens of thousands of homes below? No one knows exactly what kept the dam near Granada Hills from collapsing. 9, 1971, the top of the earthen Lower Van Norman Dam melted into the reservoir. When the Sylmar earthquake rumbled through Los Angeles 50 years ago, on Feb. history remains a matter of historical conjecture. How close Los Angeles came to what would have been - many times over- the deadliest disaster in U.S.
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