San Fernando ’71: the Earthquake That Made Us Safer

Fifty years ago, California literally got a wakeup call about natural disasters. The San Fernando Earthquake, also called the Sylmar Earthquake, struck at 6 a.m. on February 9, 1971 just north of the San Fernando Valley.

The magnitude 6.6 earthquake left 65 dead; injured another 2,000 people and caused half a billion dollars in damage (about $3.2 billion today).

“The San Fernando Earthquake changed how the state approached earthquake hazards,” said Dr. Steve Bohlen, Acting State Geologist of California and head of the California Geological Survey. “There was an increased realization that the state had to do something to limit the damage of these events.”

Legislation after the quake prompted the development of four important California Geological Survey (CGS) programs that help save Californians’ lives, livelihoods, property, and infrastructure.

1. Alquist-Priolo Fault Zoning Program

Ensures new construction does not take place atop active fault traces. “Surface fault rupture” can be devastating to buildings and infrastructure. More recently, CGS also began creating regulatory zones for earthquake-induced landslides and liquefaction. California residents can determine whether their homes are in a earthquake hazard zone by visiting the California Earthquake Hazards Zone Application (EQ Zapp).

2. Strong Motion Instrumentation Program (SMIP)

A statewide system of data-collecting instruments measure how the ground and structures such as bridges, skyscrapers, and dams react to shaking. SMIP’s data influences building codes, resulting in structures that are more earthquake-resistant. Many instruments are being modified to also contribute data to California’s earthquake early warning system.

3. Hospital review program

Hospitals were hard-hit in the San Fernando Earthquake. Now, CGS evaluates the seismic and geologic conditions when older hospitals are retrofitted and at all new hospital sites prior to construction. This ensures hospitals will not collapse because of minor faults, unstable soils, or debris flows. CGS also conducts geologic reviews for public schools.

4. Post-earthquake clearinghouses

CGS and partners establish a clearinghouse near the epicenter of large quakes, providing a headquarters for scientists and other responders to plan and coordinate research efforts, share findings, and communicate with emergency management officials.

Personal Preparation Remains Vital

California has made progress toward earthquake resilience thanks to the efforts of CGS and other agencies. But Acting State Geologist Bohlen cautions that personal preparation is vital.

“Most people will survive even the largest earthquake,” Bohlen said. “The most important question to consider is, what will you do after you survive? How well you survive depends directly on how well you prepare.”

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