NORTH COAST, Calif. — A large quake offshore of Humboldt County that was felt by thousands of people across several states and set off a series of aftershocks on Thursday morning.

The US Geological Survey said the 7.0-magnitude quake occurred at 10:44 a.m. offshore of Cape Mendocino.

It triggered phone ShakeAlerts and was reported to be felt by people not just on the North Coast but around California as well as in Arizona, Idaho, Nevada and Oregon.

As of 12:30 p.m., more than 12,500 people in 673 zip codes had reported to the USGS that they had felt the quake.

At 11:47 a.m., the USGS initially reported there was a 5.8-magnitude quake in northern Sonoma County, just west of Cobb. However, that quake was later downgraded to a 4.1-magnitude temblor.

That quake was followed at 10:48 a.m. by a 2.5-magnitude quake near Cobb, inside the Lake County border.

Lake County News readers throughout the county, Northern California and Southern California reported feeling the quake.

At 10:49 a.m., the U.S. Tsunami Warning Center issued a warning for the area stretching from 10 miles southwest of Florence, Oregon, to 10 miles northwest of Santa Cruz, California. That warning said the earthquake was 7.3 in magnitude and 8 miles deep, significantly deeper than USGS’ report had indicated.

That warning was later ended.

The Cape Mendocino quake was followed by a continuing series of aftershocks — nearly 20 of them within an hour and a half — ranging in magnitude from 2.7 to 4.3.

Within an hour of the major quake, the Sonoma County Sheriff’s Office reported that a tsunami was expected to hit Sonoma County beginning at 11:45 a.m. People were told to stay out of coastal waters and rivers, off the beaches, harbor docks and piers, as strong currents and dangerous waves are expected.

That Sonoma County warning was canceled shortly after noon.

The Mendocino College Coast Center said it closed due “to an abundance of caution” in response to the tsunami warning, but planned to reopen at 1 p.m.

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