On the 30th anniversary of the Loma Prieta Earthquake, California on Thursday became the first state in the nation to roll out a statewide earthquake early warning system.
Years in the making, the system is based on hundreds of sensors across the state that measure ground motion.
When an earthquake hits, the sensors pick up its early energy and send an instant signal to U.S.Geological Survey computers in Pasadena. Those computers then can send an alert over California’s wireless emergency alert system, which is now used for severe weather warnings and Amber Alerts, the text-message notifications authorities send out when there are child abductions.
Under the new system, anyone with a cell phone who hasn’t opted out will hear a loud tone, and a message will pop up on the screen telling them an earthquake is imminent. The idea is to provide from a few seconds to 30 seconds of warning so people can take cover and get away from things that might fall on them.
Members of the public also can download a free app created by scientists UC Berkeley called My Shake to their cell phones. The app provides people early earthquake warnings from around the state, along with the ability to report the amount of shaking they felt.
“Today we are making a big leap forward, in terms of focusing attention on prevention,” said California Gov. Gavin Newsom at a news conference Thursday in Oakland near the Bay Bridge.
Newsom said that during the 1989 earthquake he was living in apartment in San Francisco’s Marina district waiting to watch the Giants-A’s World Series game. When the building shook, he recalled car alarms going off and the ground crumbling as some homes collapsed nearby.
“It was a moment of pride and spirit, not just tragedy, seeing folks from all walks of life, neighbors, coming together,” he said.
Japan and Mexico have had similar earthquake warning systems for years, following major quakes that killed thousands of people. California and the federal government have been slow to finance a system on the West Coast, and much of the system was developed with funding from the Gordon and Betty Moore Foundation in Palo Alto. But in recent years public funding has increased.
The statewide network of sensors, which is still being expanded, is called Shake Alert. It was developed by the U.S. Geological Survey, the California Office of Emergency Services, UC Berkeley and CalTech.
The alerts also can trigger automated equipment to stop elevators so they don’t get stuck between floors of tall buildings, or open doors at fire stations so fire trucks can get out, or alert surgeons at hospitals to stop delicate operations.
Some agencies, including BART, already have early versions of the system. BART’s alert system can slow and stop trains automatically if a large quake is imminent.
Tests of the system in Oakland in March and in San Diego in June were successful.
But in July when the 7.1 Ridgecrest Quake hit in the Southern California desert, the system did not alert people in Los Angeles, who were using an early version of it, even though they felt shaking.
The reason was that planners had set it to send an alert only after a certain amount of ground shaking, and that threshold wasn’t reached in Los Angeles. Scientists have since updated the system to send alerts after quakes of 4.5 magnitude to people in areas where there is expected to be a moderate amount of shaking. The idea is to provide warning, without sending too many alerts every time there is a small quake.
