Magnitude 4.5 earthquake shakes the San Francisco Bay area - 15 oct. 2019

Magnitude 4.5 earthquake shakes the San Francisco Bay area - 15 oct. 2019
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The www.latimes.com says  in There news Title "

San Francisco Bay Area rattled by 4.5 earthquake" And in details they says : A magnitude 4.5 earthquake was felt widely in the San Francisco Bay Area at 10:33 p.m. on Monday, with the epicenter in the Walnut Creek and Pleasant Hill areas.

Moderate shaking was felt in the Pleasant Hill, Walnut Creek and Concord areas of an intensity that can overturn unsecured objects, such as books and picture frames, and is capable of breaking dishes or windows. Weak shaking was felt in San Francisco, Oakland and San Jose, according to the U.S. Geological Survey.

Close to the epicenter in Walnut Creek, there was strong side-to-side shaking, strong enough to knock CDs off a shelf.

The USGS said there is a 2% chance of one or more aftershocks larger than magnitude 4.5 over the next week, and between zero and four aftershocks of magnitude 3 and higher. “The number of aftershocks will drop off over time, but a large aftershock can increase the numbers again, temporarily,” the USGS said in its aftershock forecast.

Based on the observed shaking intensity recorded by the USGS, scientists said they didn’t expect there to be major structural damage.

The earthquake had a preliminary depth of about 9 miles underneath the surface, fairly deep for this part of the world, Keith Knudsen, USGS geologist and deputy director of the agency’s Earthquake Science Center, said in an interview. Such a deep quake made it felt widely over a broad area, but lessened the shaking intensity felt at the surface than if it were shallow, scientists said.

The earthquake was not directly on top of any of the main Bay Area earthquake faults. The epicenter was about three miles west of the Concord fault, and farther than that off the northern end of the northern Calaveras fault, Knudsen said.

The epicenter is just northwest of Mt. Diablo, one of the Bay Area’s tallest peaks. The Mt. Diablo area is also a seismically active zone, “a region of uplift, folding and thrusting,” said David Schwartz, USGS scientist emeritus.

There were a series of earthquakes in the magnitude 5 range on the southeast side of Mt. Diablo in 1980 in the Greenville fault area. On Jan. 26, 1980, a magnitude 5.4 quake hit with an epicenter only six miles from downtown Livermore. Damage in 1980 was reported at Lawrence Livermore National Laboratory and a mobile home park.

The Concord-Green Valley and Calaveras faults are among the Bay Area’s most significant.

Strong shaking from a hypothetical magnitude 6.8 earthquake on the Concord-Green Valley fault is capable of causing strong shaking in Contra Costa, Solano and Napa counties, and cause damage to the Kinder Morgan Concord pumping station, responsible for pumping fuel across the northern half of California, the Assn. of Bay Area Governments said in a report published in 2014.

The Calaveras fault can produce a quake in the magnitude 7 range, and it’s possible that it could rupture jointly with the Hayward fault, one of the nation’s most dangerous because the Hayward fault runs directly underneath densely populated cities in the East Bay, like Oakland, Berkeley, Hayward and Fremont.

Near the epicenter, it seemed the worst impact was residents shaken from sleep.

At Farrington’s Sports Bar in Pleasant Hill, about 20 patrons were playing pool and darts and watching TV when the earthquake started.

Bartender Casey Ashimine said no bottles broke but it was definitely apparent that they were experiencing an earthquake.

“A good little shaker,” Ashimine said. “A couple people looked around, but nobody freaked out.”

Assistant Chief Chris Bachman of the Contra Costa County Fire Protection District, which provides emergency services to communities close to the quake’s epicenter, said that as of about 11 p.m., there were no reports of injuries or property damage related to the earthquake.

The earthquake occurred just three days before the 30th anniversary of the magnitude 6.9 Loma Prieta earthquake, which killed 63 people in Northern California.

In the last 10 days, there have been two earthquakes of magnitude 3.0 or greater centered nearby.

An average of 25 earthquakes with magnitudes between 4.0 and 5.0 occur each year in California and Nevada, according to a recent three-year data sample.

Did you feel this earthquake? Consider reporting what you felt to the USGS.

Find out what to do before, and during, an earthquake by reading our five-step earthquake preparedness guide.

Times staff writer Mark Z. Barabak contributed to this report.

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The www.nbcnews.com  says : 

By Phil Helsel and Kurt Chirbas

A 4.5-magnitude earthquake shook the San Francisco Bay Area Monday night, and while some damage is possible, injuries are unlikely, the U.S. Geological Survey said.

The temblor struck around 10:30 p.m. about 0.62 miles south-southeast of Pleasant Hill, a city of about 33,000 around 20 miles northeast of downtown San Francisco, according to the agency. It had a depth of around 9 miles.

An earthquake of that intensity is not an everyday occurrence but is fairly typical for the area and well within the seismic norm for the region, USGS geophysicist Amy Vaughan.

There is no tsunami threat, officials said.

The sheriff in Contra Costa County, where Pleasant Hill is located, tweeted that there had been no calls of injuries reported to the sheriff's office.

The strength of the earthquake may have woken up sleeping residents and displaced items on walls or cabinet tops, Vaughan said.

Another 2.5-magnitude earthquake was reported in the same area minutes before the larger quake, according to the USGS website.

The National Weather Service tweeted that it did not feel the earthquake at its office in Monterey.But, Maryanna Boddari, of San Ramon, a city in the area of the epicenter, did. She described the shaking as "extremely intense."

"It actually felt like my house was being torn down," she told NBC Bay Area in a phone interview. "I've felt earthquakes before, but this was really, really intense."

Boddari said the quake lasted for around 30 seconds to a minute and knocked over a lamp in her home.

Tim Gaxiola, of Pacheco, which is north of Pleasant Hill, told the station that "I didn't just feel something; I heard a snap, a loud crack" and then a rolling motion. "The roll lasted quite a long time, and it seemed to circle around about a good 10 to 15 feet in a circular motion," he said.

"It was definitely a heavy-duty shake," Gaxiola said.

Bay Area Rapid Transit tweeted that trains were running at reduced speeds and track inspections were being conducted. 

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The www.usatoday.com  says : 

Magnitude 4.5 earthquake shakes the San Francisco Bay area

SAN FRANCISCO – The San Francisco Bay Area widely felt a magnitude 4.5 earthquake.

The Los Angeles Times reports moderate shaking was felt at 10:33 p.m. on Monday, with the epicenter in the Pleasant Hill and Walnut Creek areas.

The U.S. Geological Survey says weak shaking was felt in San Francisco, Oakland and San Jose. Scientists say they don’t expect any major structural damage.

Keith Knudsen, USGS geologist and deputy director of the agency’s Earthquake Science Center, told the Times that the earthquake had a preliminary depth of about 9 miles underneath the surface, fairly deep for this part of the world.

Assistant Chief Chris Bachman of the Contra Costa County Fire Protection District said that as of about 11 p.m. Monday, there were no reports of injuries or property damage related to the earthquake.