Aftershocks can also be a troubling sign for Californians. We always hope that the aftershocks are just the faults shifting and releasing the pressure of the moving plates in a small way each time. It's when the pressure builds and we get a big quake of 6.5 to 7.0 it's a problem.
Because a 5 is 1/10 the size of a 6 and a 6 is 1/10 the size of a seven. If you live in California you know this stuff but you might not if you don't live on the Ring of Fire that encircles the Pacific Rim from Washington to California to South America to Japan and elsewhere along the way. So, what I'm saying here is that a 7 is 100 times more powerful than a 5 earthquake.
This quake was felt as far south as Temecula by the way which is north of where I'm staying now in San Diego County.
begin quote from: https://www.cbsnews.com/losangeles/news/preliminary-5-7-magnitude-earthquake-strikes-near-bakersfield-shakes-all-the-way-to-la-county/
Dozens of aftershocks follow 5.2-magnitude earthquake near Bakersfield that rattled Southern California all the way to LA
A preliminary 5.2-magnitude earthquake struck near Bakersfield and shook all the way to Los Angeles County.
It happened at about 9:09 p.m., roughly 14.29 miles southwest of Lamont, California, which borders Bakersfield. It is a relatively rural area about 89 miles north of downtown Los Angeles.
Immediately after the earthquake, the Los Angeles Fire Department deployed its helicopters to survey the region for any potential damages.
"Our @LAFD has activated to conduct its routine survey of the city and assess for any damages," Mayor Karen Bass posted on X." City teams will continue to monitor any impacts."
After conducting the survey, firefighters found no significant damage to the infrastructure or any buildings. LAFD received zero injury reports within LA city limits.
Geologists believe there is little to no risk of landslides or liquefaction in the area, according to the USGS.
Aftershocks
More than two dozen earthquakes followed the original, with magnitudes between 2.5 and 4.5. The aftershocks struck near Lamont and Grapevine. About 25% of the aftershocks tend to happen within an hour after the original quake.
The USGS recorded three aftershocks above magnitude 4.0. The vast majority of the aftershocks, about 15, were below magnitude 3.0. About nine more magnitude 3.0 to 3.8 earthquakes struck the region shortly after the original.
"That's a pretty active sequence for this very short amount of time since the event," seismologist Dr. Lucy Jones said.
She said the aftershocks were within the range of a typical sequence of earthquakes.
Cal Tech seismologists weigh in
The United States Geological Survey posted a map depicting the intensity of the shaking in the regions surrounding Lamont. According to the map, the shaking was mild in LA County but between light and moderate near the epicenter of Lamont.
Allen Husker, a seismology research professor at the California Institute of Technology, attributed the shaking in LA to the basin effect. Basins, due to their softer nature, tend to magnify the shaking.
Jones said the earthquake originated in the southern end of the Central Valley, close to the epicenter of a magnitude 7.5 earthquake that rocked the region in 1952.
"However, it does not appear to be on the same fault as that earthquake," she added. "It doesn't look like this [recent] earthquake is associated with any known fault."
Jones believes there is a 5% chance that the 5.2-magnitude earthquake was a foreshock, similar to every other earthquake in California. There is no indication that this event is any different.
"In terms of the chances that this is a foreshock, we have the same answer for every earthquake: it's about a 5% chance," she said. "1 in 20 earthquakes in Southern California we see are followed by something larger and turns out to be a foreshock within the next few days."
The risk of earthquakes being a foreshock drastically drops with time.
"One-quarter of all foreshocks are within an hour of the main shock," Jones said. "By the time that we get to three days out ... essentially the risk will be all gone."
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