Seismologists say a new warning system being tested gave them nearly a full minute warning that an earthquake was coming, but residents in Southern California said they did not receive the alert.
Bay Area residents have seen a "shake alert" in action as it was developed, and on Thursday, United States Geological Survey officials said the warning system worked during the Ridgecrest earthquake.
"The idea is to give you warning that an earthquake has occurred, and you're about to feel a strong shaking," said Dr. Angela Chung, an early warning expert with the UC Berkeley Seismology Lab.
Chung said the alert worked and gave the USGS about 48 seconds worth of warning Thursday. But the alert did not go out to the people in Los Angeles because it didn’t measure strong enough.
"We know that the system worked, but the app has parameters; it doesn't give a message if it’s below this level," said Dr. Lucy Jones, a seismologist with Caltech.
By the time the quake reached the big cities, it didn’t trigger the alert, Chung said. The alert has a limit so residents don’t receive a notification every time there is an earthquake.
"We don’t want to be a nuisance, to tell you about every little teeny, tiny earthquake because that’s not what the system is designed for," Chung said. "The system is designed to save lives and property and damage."
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Experts said it’s a fine line between providing an ample warning in advance of a strong earthquake or "over" warning residents ahead of the small ones.
