An article published Sunday detailed how Los Angeles, California sits atop a giant “bowl of jelly” that could prove deadly in future earthquakes.
Earthquakes are nothing special or new to Californians, as the state experiences the second highest frequency of tremors in the nation (coming after Alaska), the BBC wrote in their Sunday analysis. Every three minutes, something shifts in Southern California but most of these quakes are too small to feel on the surface. But recent quakes have shed light on the unique nature of the region’s geology.
On August 6, a magnitude 5.2 quake struck about 17 miles south of Bakersfield but people reported shaking nearly 90 miles away in parts of L.A. and San Diego. Researchers now think this is because L.A. sits on top of a “five-mile-deep sediment-filled basin” that influences the way earthquakes hit the city and wider county, according to the BBC.
Outskirts Of Chicago Hit With Earthquakehttps://t.co/cmq3RlDxtc
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“Imagine the Los Angeles basin as a giant bowl of jelly – the mountains and underlying rock make up the bowl, while the sediment is represented by the gelatinous mixture,” the BBC wrote, before quoting University of Southern California seismology professor John Vidale. “If you shake the bottom [of the bowl] a little bit, the top flops back and forth quite a bit,” he explained to the outlet. (RELATED: Canada Experienced Almost 2,000 Earthquakes In A Single Day. But Why?)
The mixture under L.A. is actually gravel, sand and clay, according to a U.S. Geological Survey factsheet. As the city is located south of a large turn in the San Andreas fault, millions of years of activity has ground down the mountain ranges, with water, gravity and wind carrying debris (sediment, the ‘jelly’) into the basin.
DESERT HOT SPRINGS, CA – MARCH 31: In an aerial view from a drone, homes are seen on top of a fault scarp over the San Andreas Fault on March 31, 2021 in Desert Hot Springs, California. Desert Hot Springs is famous for its hot water pressed to the surface from the fault. The San Andreas Fault, long feared for its potential to cause the biggest natural disaster ever in Southern California, is capable of producing and 8.1-magnitude earthquake that could killed thousands of people and cause hundreds of billions of dollars in damage. The southern segment of the fault, extending for hundreds of miles from the Salton Sea in the south, passes as close as 35 miles from Los Angeles, through the Big Bend section in Kern County and on to Parkfield in Monterey County. It is the Big Bend section of the fault that is believed to have become locked, preventing the fault from slipping to release the ever-increasing pressures caused by the grinding of the Pacific and North American tectonic plates. The locked fault is rapidly increasing the risk of the long overdue “Big One” quake that scientists say is inevitable. (Photo by David McNew/Getty Images)
MECCA, CA – APRIL 2: In an aerial view from a drone, colorful minerals are seen on the Pacific Plate side of the San Andreas Fault, where it collides with the North American Plate, in the southwestern section of the Mecca Hills on April 2, 2021 near Mecca, California. The San Andreas Fault, long feared for its potential to cause the biggest natural disaster ever in Southern California, is capable of producing and 8.1-magnitude earthquake. The southern segment of the fault, extending for hundreds of miles from the Salton Sea in the south, passes as close as 35 miles from Los Angeles, through the Big Bend section in Kern County and on to Parkfield in Monterey County. It is the Big Bend section of the fault that is believed to have become locked, preventing the fault from slipping to release the ever-increasing pressures caused by the grinding of the Pacific and North American tectonic plates. (Photo by David McNew/Getty Images)
(Original Caption) Los Angeles, California: Earthquake Aftermath. (Photo by David Butow/Corbis via Getty Images)
Fire spouts from a flooded Los Angeles highway following the Northridge earthquake. (Photo by �� Steve Starr/CORBIS/Corbis via Getty Images)
1/18/94. Los Angeles, California. The 6.6 temblor took the life of a motorcycle police officer on this section of freeway at 4.31am
Seismic waves move faster in hard rock than in soft material but still have to carry the same energy, Vidale told the BBC. When a quake goes from hard to soft sediment, the height (or amplitude) grows substantially. And this is the dangerous part, he noted to the outlet. (RELATED: Huge US Fault Zone Could Be Ramping Up For Earthquake, Scientists Say)
Basically, people in L.A. are living in the one place where earthquakes will probably hit harder than in surrounding regions that are not within the basin. The geology of the region can literally “trap seismic wave energy,” the Southern California Earthquake Center found in 2014. This means shaking goes on for longer than the actual fault fracture, according to a study.
All of this adds up to another major threat facing Southern California. And unlike terrible policies leading to social decline, this threat cannot be mitigated by the voters.
