Swarms of quakes within minutes wake up Los Angeles region, seismologists report

A swarm of earthquakes shook the Los Angeles area awake Thursday morning, the U.S. Geological Survey reports.

A 3.3-magnitude tremor hit off San Buenaventura State Beach Park in Ventura at 4:58 a.m. Pacific time, according to the USGS. A 3.4-magnitude quake followed at 5:05 a.m. Pacific time. Both were about 8 miles deep.

Ventura lies about 70 miles northwest of downtown Los Angeles.

Hundreds of people from as far away as Sylmar, Pomona and Santa Barbara reported feeling the tremors to the agency.

“Okay... now feeling a moderate earthquake here in Ventura,” wrote one person on Twitter.

‘Just felt a small earthquake here in Ventura...,” read another Twitter post.

A 2.3-magnitude quake shook downtown Ventura at 6:33 a.m., while two more small quakes, at 2.3 and 2.4 magnitudes, hit off the shore of Ventura, near the earlier larger quakes, just before 7 a.m., the USGS reported.

Numerous smaller quakes, mostly below 2.0-magnitude, also have shaken the area north of Ventura, the agency says.

Two early morning quakes also shook the Ridgecrest, California, area, where two major quakes hit over the summer, according to the USGS.

A 2.9-magnitude quake hit at 2:46 a.m., followed by a 3.5-magnitude tremor at 4:38 a.m., the agency says. The region has been shaken by a series of small quakes for months.

A 6.4-magnitude quake hit near Ridgecrest at 10:33 a.m. July 4, followed by a 7.1-magnitude quake at 8:19 p.m. July 5, The Sacramento Bee reported.

The second quake caused fires, power outages and some damage in the Searles Valley area around Ridgecrest, near the Mojave Desert, according to the publication.

Thousands of aftershocks followed, continuing steadily for months.

Magnitude measures the energy released at the source of the earthquake, the U.S. Geological Survey says. It replaces the old Richter scale.

Quakes below 4.0 magnitude are sometimes felt but rarely cause much damage, according to the USGS. Those below 3.0-magnitude may not be noticed by most people..

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Don Sweeney has been a newspaper reporter and editor in California for more than 25 years. He has been a real-time reporter based at The Sacramento Bee since 2016.