Photo: Dietmar Rabich / Wikimedia Commons (CC BY-SA 4.0)
On Sept. 19, 2017, a magnitude 7.1 earthquake struck central Mexico, killing more than 300 people, many of them in Mexico City. It happened on the anniversary of the devastating 1985 Mexico City earthquake. Many San Diegans have family and friends in Mexico, and the disaster was a reminder that Southern California is earthquake country too.
The faults beneath San Diego
The Rose Canyon fault zone runs from offshore near La Jolla through Rose Canyon, Old Town and downtown San Diego and into San Diego Bay. Geologists consider it capable of producing an earthquake around magnitude 6 to 7. Farther east, the Elsinore and San Jacinto faults cross the county’s inland areas, and the San Andreas lies beyond in the desert.
Early warning
The U.S. Geological Survey’s ShakeAlert system detects earthquakes as they begin and can send alerts seconds before strong shaking arrives. In California, alerts reach phones through Wireless Emergency Alerts, Android phones’ built-in system and the state’s MyShake app. A few seconds is enough to drop, cover and hold on, or to step away from a window.
When the shaking starts
- Drop to your hands and knees.
- Cover your head and neck, under a sturdy table if possible.
- Hold on until the shaking stops.
Before it happens
- Secure heavy furniture and water heaters to walls.
- Keep water, food, medications and a flashlight for at least several days.
- Know how to shut off your gas if you smell a leak.
- Take part in the Great California ShakeOut drill each October.
Sources: U.S. Geological Survey Earthquake Hazards Program; Cal OES: MyShake and earthquake early warning; Great California ShakeOut.
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