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Hundreds of aftershocks caused by a magnitude 7.1 earthquake on Friday night caused a fragile night in the Mojave Desert in southern California.
The earthquake, the strongest in 20 years in southern California, struck shortly after 20 hours.
It was centered 11 miles from the city of Ridgecrest, which was already in recovery mode after a magnitude 6.4 earthquake the day before July 4 in the morning. Seismologists said the initial earthquake was a shock to the very powerful earth-quaker who struck Friday night.
This sequence of events, a large earthquake followed by an even more powerful earthquake, is a known phenomenon.
"It's the same sequence," Dr. Lucy Jones said on Twitter Friday before speaking to CalTech's media. "You know we say 1 chance out of 20 that an earthquake is followed by a more serious event? It's 1 in 20 times."
WHO THE FELT IT
The Friday night shocks were felt in a vast region, from Las Vegas to Los Angeles, Mexico City and Sacramento. It was preceded by a few minutes with an earthquake of magnitude 5.0 and followed by a few tens of seismic aftershocks recording a level above 4.0.
Seismologists have warned that it was still possible that an earthquake of size greater than 7.1 will occur in the Little Lake fault zone that has been so active in recent days.
Officials have declared early warning systems worked for residents closer to the epicenter where the quake was the strongest. But Los Angeles residents have not received warnings from ShakeAlertLA before one of the major earthquakes.
When the magnitude 6.4 did not trigger any notifications from the application, many residents wondered why.
The answer? The warning threshold was higher than the planned earthquake in Los Angeles. The application warns users only when the earthquake likely to be felt in L.A. County is greater than 5.0. After the earthquake yesterday, officials announced that they would lower this threshold to 4.5, but the application will not be updated until the end of the month.
Jones, who played a major role in urging the region to do more to prepare, said the current warning system is far from complete.
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"There was a proposed budget that was very simple and we did not even understand it.The system is not yet operational," Jones told our science reporter, Jacob Margolis, Saturday morning. "The system is not working very well, not because we have not paid enough."
Fires, injuries and significant damage to roads and shops have been reported.
At a magnitude of 7.1, the Friday night earthquake falls into the category of major earthquakes, but that was not what everyone learned from "big".
By comparison, the 1994 Northridge earthquake, with a magnitude of 6.7, struck more than 50 people, injured thousands of others, and caused billions of dollars in damage. a densely populated region.
This is a story in development. Check back regularly for updates throughout the day.
Sharon McNary, Jacob Margolis and Megan Garvey contributed to this report.
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