California earthquake occurred along active fault, experts say. Aftershocks expected
A magnitude 7.0 earthquake that occurred off the coast of Northern California Thursday will continue to produce aftershocks for days, experts with the U.S. Geological Survey said Thursday.
The earthquake occurred along the Mendocino Fracture Zone, which is an active area that frequently experiences events of this magnitude.
“This is an area in Northern California that’s highly tectonically active,” Stephen DeLong, a Supervisory Research Geologist with the USGS, said during a press briefing. “It’s an area where they’re at least three different tectonic plates that move in different directions and at different speeds. And because of that, earthquakes occur frequently.”
In recent years, the fault area has experienced a similarly sized earthquakes, said DeLong. A magnitude 6.4 earthquake struck Ferndale in Humboldt County in 2022.
Thursday’s earthquake was eight times bigger than the 2022 event, said the USGS’ ShakeAlert System’s Operations Team Lead Robert de Groot.
DeLong said the largest earthquake this region in the last century was a magnitude 7.4 in 1922.
“Since the earthquake, there’s been a fairly robust aftershock sequence, and these this is going to be ongoing for days and weeks after this event,” said DeLong.
DeLong and de Groot said residents should be ready to take protective action as more shaking is expected. There have been at least three or four aftershocks since the initial event, de Groot said.
Half a million people in the region received alerts on their phones, which were sent to cities as far north as Bend, Oregon and as far south as Salinas.
The National Oceanic and Atmospheric Administration issued a tsunami alert earlier in the day, but that warning has since been rescinded.
DeLong said this region is considered “earthquake country,” and Thursday’s event serves as a good reminder that these events happen and people should be prepared by signing up for ShakeAlerts.
As a resident of the region, James Haynes said he’s so accustomed to earthquakes that he didn’t take Thursday’s event “as serious as I should have.”
The Blue Lake retiree said he was driving to Costco in Eureka when he received an alert about the earthquake, though he didn’t feel any shaking. He continued on his way and realized the severity of the event when store employees began ushering shoppers out of the building after he arrived.
On his drive back home, Haynes said he saw groups of people who had been escorted outside a grocery store and university buildings.
Upon returning home, he found his two rescue dogs, Scout and Bingo, shaken. He said the only damage to his home was several picture frames that had been knocked off walls by the shaking. He called his wife, who was in a nearby town closer to the ocean, to make sure she was fine.
“We experience many quakes in Humboldt [County], most of the minor but sometimes very scary quakes that make you roll over in bed, put the pillow over the top of your head and just hope everything’s going to be all right,” Haynes said.
This story was originally published December 5, 2024 at 1:41 PM.
