Did you feel it? Fresno, Merced and the Valley shaken by Thursday afternoon earthquake
An earthquake jolted Fresno, Merced and other parts of the Central Valley at about 3:50 p.m. Thursday.
A preliminary report from the U.S. Geological Survey indicates that the temblor was centered south of Topaz Lake, in Mono County not far from the California/Nevada state line. The earthquake was initially estimated at 5.9 magnitude, but was later upgraded to 6.0-magnitude.
The estimated epicenter is about 110 miles northeast of Fresno.
Social media posts in the immediate aftermath of the jolt indicated that the earthquake was also felt at least as far north as Sacramento and southward to Exeter in Tulare County.
A USGS shake map produced by people who reported feeling the quake shows that it was felt as far south as Bakersfield, west to the Central Coast, east across much of Nevada, and almost as far north as the California/Oregon state line.
By 6 p.m., more than 30 aftershocks ranging in magnitude from 2.5 to 4.6 were registered by USGS.
Austin Elliott, a research geologist with the U.S. Geological Survey, said the agency is estimating a 6% chance of an aftershock that is larger than the original earthquake, but he added that is a small chance and called it “a particularly unlikely scenario.”
There were no immediate reports of damage in the Fresno area from the earthquake.
The Fresno County Sheriff’s Office did not receive any immediate calls for service related to the earthquake, according to Tony Botti, the sheriff’s spokesperson. Authorities in Merced County also had no reports of damage.
“We are doing some proactive checks around our headquarters and patrol is putting eyes to some of the prominent structures” such as dams at Millerton and Shaver lakes in eastern Fresno County, he said.
‘Not particularly uncommon’
Elliott said the earthquake happened on what is known as the Antelope Valley Fault on the east side of the Sierra Nevada range. The quake itself has been tentatively dubbed the Antelope Valley quake (the sparsely populated area of Mono County is not to be confused with the more populous Antelope Valley to the south in eastern Los Angeles County).
Elliott described the occurrence of the earthquake as “not particularly uncommon” because the region is a known area of tectonic activity. “There have been a couple of dozen quakes larger than magnitude 5 in the past 50 years,” he said. “In the last year we’ve seen a fair number of earthquakes around this region.”
“This was a much stronger jolt, and probably more of a fairly good shake that was pretty alarming if you were in Carson City or Reno,” Elliott added. The 6.0 shaker, he said, is the largest in the region since the 6.1-magnitude Double Spring Flat earthquake, which occurred in 1994 in western Nevada.
Much less common, however, is for a quake on the east side of the Sierra to be felt in the Central Valley. “There was likely some amplification in places that are built upon sediments and flat soils,” Elliott said. But, he added, that a 6.0-magnitude earthquake “shakes more strongly and has a wider reach than many others.”
A 6.0-magnitude quake, for example, is 10 times stronger than one that measures 5.0.
Caltrans checking in
State Sen. Andreas Borgeas, R-Fresno, told The Bee that he was driving in his car when he felt the quake, but didn’t realize at first that the ground was shaking.
“The car started to act up, but I thought it was because I have an old beat-up car with old tires and a bad engine,” he said with a laugh.
Borgeas said he learned from the state Office of Emergency Services that Caltrans, the state highway department, is sending crews to the area to inspect roads and structures for possible damage from the quake in Mono and Inyo counties.
“The way it’s been described to me, what makes this a little unusual to experience is that these (aftershocks) are happening in such quick succession, back to back, one on top of the other,” he said.
No problems were being reported at Yosemite National Park or Yosemite Valley, about 50 miles from the epicenter, said Scott Gediman, a spokesman with the National Park Service.
No major damage in Mono County
Borgeas said he learned from Mono County Sheriff Ingrid Braun that the only reported problem in the county was a rockslide in a canyon near Bridgeport.
He added that the sheriff reported that there was no serious damage from the earthquake, and no reports of anyone being hurt or killed.
Elliott, the USGS geologist, said there were reports of rockfall on Highway 395, the main highway artery on the east side of the Sierra, near Coleville, less than four miles from the epicenter.
This story was originally published July 8, 2021 at 4:11 PM.
