SAN FRANCISCO ‒ A magnitude 7.0 earthquake struck near the town of Petrolia in California on Thursday at 10:44 a.m. local time, generating a now discontinued tsunami warning that stretched from southern Oregon to San Francisco.
The quake occurred near the sparsely populated northern coast of California, just offshore on the San Andreas fault, which runs along the coast line.
In Arcata, California, just under 60 miles from Petrolia, 25-year-old Jared Mitchell was having an early lunch in his apartment when he felt a “jolt,” he told USA TODAY.
“It wasn’t that big of a violent shake,” said Mitchell, an assistant manager at Los Bagels, a bagel shop in town. “But my apartment was swaying back and forth for a bit. It was kind of scary, like I was on a raft in the middle of the sea.”
By 12:30, less than two hours after the initial quake, the area had experienced 13 different aftershocks, ranging from 5.1 to 3.1, according to the U.S. Geological Survey.
The tsunami warning center canceled its warning at 11:54 a.m. local time and said no tsunami observations were available to report. “No destructive tsunami has been recorded,” the warning center said. However, it advised the public not to re-occupy hazard zones until local emergency officials indicate it is safe to do so.
How many people felt the earthquake?
USGS initially estimated more than 150,000 people might have been exposed to earthquake shaking, between just north of Fort Bragg to Eureka. One USA TODAY reporter in San Francisco did not feel its impacts.
In Arcata, Mitchell said he hasn’t seen any apparent damage in town so far.
“We’re okay, for now,” Mitchell said.
More: Earthquakes happen all the time, you just can’t feel them. A guide to how they’re measured
See where the epicenter was
Earthquake rocks San Andreas fault
The Earth’s crust is made up of many tectonic plates that move slowly over the Earth’s surface. Thursday’s earthquake hit at the Mendocino Triple Junction, a tectonic boundary where three plates meet: the Pacific, North American and Juan de Fuca, along the San Andreas Fault.
The Triple Junction is the point that the Northwest’s northern Cascadia subduction zone and the southern San Andreas Fault system meet. Large earthquakes also occurred near the junction in northern California in previous Decembers, according to the geological survey. There were two, a 6.1 and 6.0, near Petrolia in 2021 and a 6.4 near Ferndale in 2022.
The San Andreas fault is the place where the Pacific Plate and the North American Plate meet along the coast of western California. It is 800 miles long and extends at least ten miles into the Earth, according to USGS.
The San Andreas was the site of one of the most well-known temblors in history, the 1906 San Francisco earthquake which devastated the entire San Francisco Bay area and killed as many as 3,000 people, according to USGS.
How common is a Bay Area tsunami warning?
The last time a tsunami warning was issued for the Bay Area was in January 2022, after the eruption of the Hunga Tonga volcano, said Dalton Behringer with the weather service.
Between 1850 and 2004, 51 credible tsunamis were recorded in San Francisco Bay, according to 2004 research led by Lori Dengler, a professor emeritus at Cal Poly Humboldt. Only two of those generated damage, the 1960 Chile earthquake and the 1964 Alaska earthquake, which generated waves of almost 4 feet at the Presidio, the authors reported.
Previous tsunami warning canceled
Previously, a tsunami warning advised a tsunami could arrive along the coast starting near Fort Bragg at 11:10 a.m. local time and move along the coast in northern California and southern Oregon, arriving in San Francisco at 12:10. Residents within the zone – stretching from Davenport, California, northwest of Santa Cruz, to the Douglas Lane county line in Oregon – were urged to move off the water and beach and evacuate inland beyond tsunami hazard zones.
“Move out of the water, off the beach, and away from harbors, marinas, breakwaters, bays and inlets,” the National Tsunami Warning Center advised. “Repeated coastal flooding is possible as waves arrive onshore, move inland, and drain back into the ocean.”
Just how big is a 7.0 quake?
Magnitude is a measurement of the strength of an earthquake. Officially it’s called the moment magnitude scale. It’s a logarithmic scale, meaning each number is 10 times as strong as the one before it. So a 5.0 earthquake is ten times stronger than a 4.0.
The magnitude and effect of an earthquake, according to Michigan Technological University:
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Below 2.5: Generally not felt
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2.5 to 5.4: Minor or no damage
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5.5 to 6.0: Slight damage to buildings
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6.1 to 6.9: Serious damage
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7.0 to 7.9: Major earthquake. Serious damage.
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8.0 or greater: Massive damage, can destroy communities
Preliminary data from the US Geological Survey indicates a 32% chance of estimated economic losses at $1-$10 million, and a 32% chance of economic losses between $10-$100 million, with the chances of losses greater than that estimated at 15%.
This story will be updated.
This article originally appeared on USA TODAY: Major California earthquake triggered tsunami warning: Updates
