Magnitude 5.1 Earthquake Strikes in San Francisco Bay Area After Calaveras Fault Rumbles History

Tuesday's earthquake, which had a magnitude of 5.1, was brought on by the Calaveras Fault strike-slip fault line.

According to the U.S. Geological Survey, a 4-mile deep epicenter was located 12 miles (19 kilometers) east of San Jose (6 kilometers) at 11:42 a.m local time. A hilly region lies about 40 miles (64 kilometers) southeast of San Francisco's central business district.

Major Silicon Valley Reservoir To Be Drained Due To Earthquake Risk

(Photo : Justin Sullivan/Getty Images)
MORGAN HILL, CALIFORNIA - FEBRUARY 25: Water lines are visible along the banks of the Anderson Reservoir on February 25, 2020 in Morgan Hill, California. The Santa Clara County Water District is moving forward with plans to drain the Anderson Reservoir due to a high risk to the public in the event of a significant earthquake. The Anderson Reservoir is the largest in Santa Clara County and along sits the Calaveras Fault.

Magnitude 5.4 Earthquake in San Francisco Bay Area Recorded

According to seismologist Lucy Jones (via Twitter), the quake was the biggest the Bay Area had seen in a long time. The most recent significant earthquake was a 6.0-magnitude one that occurred close to Napa in 2014.

The Bay Area earthquake was on the Calaveras fault. The largest quake in the Bay Area since the 2014 Napa quake M6.0https://t.co/nbDx242Rmv
— Dr. Lucy Jones (@DrLucyJones) October 25, 2022

Jones added in a separate KNTV-TV report that the Calaveras Fault, one of eight significant faults in the Bay Area and a branch of the San Andreas Fault line, caused the earthquake .

The Monterey office of the National Weather Service (per USA Today) reported some shaking. According to tweets from BART and Caltrain, trains temporarily stopped running before restarting at slower rates.

There have been no substantial reports of damage following the earthquake, according to Santa Cruz County's tweet. According to the county, there was no school damage, and classes may resume without risk.

The County is checking in with partner agencies but we do not have significant reports of damage at this time. Please do not call 911 unless you have an emergency.
— Santa Cruz County (@sccounty) October 25, 2022

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According to the California Governor's Office of Emergency Services (Cal OES), almost 100,000 individuals reported receiving a warning before the shaking began through the state's earthquake early warning system.

The Loma Prieta earthquake, a magnitude 6.9 tremor that rocked the Santa Cruz Mountains on October 17, 1989, just as the World Series was about to start in San Francisco, happened 33 years ago this week. Sixty-two people died as a result of the earthquake, which also cost billions to repair.

What Calaveras Fault Had To Do With the Earthquake

KRON4 said that Calaveras Fault - which extends from Hollister, near Gilroy, to Danville and beyond - has been "seismically calm" these past ten years. When the 5.4-magnitude Alum Rock earthquake erupted last year, it was the region's most recent significant earthquake.

Along with the magnitude-5.9 Coyote Lake earthquake in 1979, the fault line was also responsible for the magnitude-6.2 Morgan Hill earthquake in 1984.

KRON4, citing the Working Group for California Earthquake Probability, states there is an 11 percent chance that an earthquake of magnitude 6.7 or higher will occur on the Calaveras Fault during the next 30 years.

However, this 100-mile length of the East and South Bay geography, where enormous chunks of the earth's crust scrape past one another in different directions, was reminded of the potent pent-up energy by Tuesday's 5.1 earthquake.

"The Calaveras Fault is right up there, with those two other faults, in terms of its ability to generate earthquakes," Richard Allen, director of the Berkeley Seismology Lab, told Mercury News.

Because the zone is filled with slick rocks and minerals, the Calaveras fault often merely creeps. It may now slide to release energy.

It moves around 0.2 inches each year on average. Although this is annoying, stressing pipes and causing sidewalks to fracture, for example, it is seldom disastrous.

Austin Elliott, earthquake geologist with the U.S. Geological Survey also told that the Calaveras Fault must accommodate the Pacific Plate's movement northward close to North America.