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. 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 “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.

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