- The July 5 earthquake was the biggest to hit Southern California in 20 years.
- Scientists didn’t know the fault the existed before the quake.
- Researchers have installed 25 seismic sensors to study aftershocks in the region.
Scientists had no idea the fault that caused a 7.1 magnitude earthquake in Ridgcrest, California, existed until the area was rocked by the quake on July 5.
Almost immediately, research began to understand the unnamed fault and help local officials prepare for the next big seismic event, according to a press release from the University of California Riverside.
“It’s not a matter of ‘whether’ there will be another large quake in California,” Abhijit Ghosh, a geophysics professor at UC Riverside, said in the release. “It’s an inevitability.”
A series of quakes and aftershocks jolted the Ridgecrest area in July. The July 5 temblor was the largest to hit Southern California in 20 years. A smaller quake on July 4 happened on different faults, according to the press release.
Ghosh and a team of researchers set out on July 6 to install a series of 25 seismometers in the ground to measure the thousands of aftershocks.
“These instruments are extremely sensitive,” Ghosh said. “They can detect and locate even very tiny earthquakes very precisely.”
The sensors provide data on the size, location and time of the aftershocks. The researchers will use that information to create a three-dimensional map of the fault to help understand the evolution of the stress within it leading up to the big earthquake.
They are also hoping to discover whether the smaller earthquake a day before triggered the larger one, and whether the larger quake affected other nearby faults. Of specific interest is the nearby Garlock fault, which is about 150 miles long.
The length of a fault determines the magnitude of an earthquake, Ghosh said, so stress to the Garlock fault is a concern.
“If Garlock goes, it will create a much larger event than Ridgecrest, which is estimated to be only about 40 miles long,” he said.
While he stressed that he doesn’t want to create undue alarm, Ghosh noted that aftershocks are reaching all the way to Garlock and it has been more active since Ridgecrest.
“The more we understand about the physics behind earthquakes, the better we can prepare to combat their hazards,” Ghosh said.
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