At 6 o’clock in the morning on February 9, 1971, the reservoir keeper of the Lower Van Norman Dam in Southern California tried to get out of bed.
He couldn’t. A magnitude-6.6 earthquake was shaking his home nestled at the bottom of the dam. After checking on his wife and child, he drove to the top of the dam to examine the damage. “It was hard to believe what I saw,” he said.
The Lower Van Norman Dam, which sat above the San Fernando Valley in Los Angeles County, had nearly collapsed in the wake of the quake. “As wind-whipped waves chewed at the damaged lip of the 1,100-foot Van Norman Dam, police spread through a nine-square-mile area between the reservoir and the Ventura Freeway, warning residents to evacuate,” The Los Angeles Times reported on February 10, 1971. Approximately 80,000 people did evacuate as officials lowered the water levels in the dam.
The 1971 San Fernando, or Sylmar, earthquake was the worst to hit an urban area of California since the 1933 magnitude-6.4 Long Beach quake. It led to 64 deaths and more than $500 million in damage. It prompted Governor Ronald Reagan to declare Los Angeles County a disaster area and President Richard Nixon to send Vice President Spiro Agnew to inspect the area.
After the San Fernando earthquake, the State of California enacted the Alquist Priolo Act to limit construction along faults that likely caused earthquakes able to rupture the ground surface in the last 11,000 years.
On the federal level, Congress renewed its interest in earthquake safety, held hearings and introduced new bills to establish a national earthquake research program. Congress eventually passed the Earthquake Hazards Reduction Act of 1977, which led to the National Earthquake Hazards Reduction Program, or NEHRP, and was pivotal in helping establish what is now the USGS Earthquake Hazards Program.
Over the years, NEHRP agencies, including the Federal Emergency Management Agency (FEMA), the National Institute of Standards and Technology, the National Science Foundation and the U.S. Geological Survey, made research and policy recommendations that in part contributed to the City of Los Angeles enacting an ordinance in 2015 to retrofit weaker first-story wood-frame buildings and non-ductile, or brittle, concrete buildings, which are both more vulnerable to collapse during strong shaking. In 2013, San Francisco enacted the Mandatory Soft Story Retrofit Program, which was based in part on work sponsored by NEHRP and on the aftermath of the 1989 Loma Prieta earthquake.
“NEHRP was founded on the belief that while earthquakes are inevitable, there is much that we can do as a nation to improve public safety, reduce losses and impacts and increase our resilience to earthquakes and related hazards,“ Gavin Hayes, the USGS senior science advisor for Earthquake and Geologic Hazards, said.