(Stars and Stripes)
RONG-GONG LIN II October 17, 2019
LOS ANGELES — A major California fault capable of producing a magnitude 8 earthquake has begun moving for the first time on record, a result of this year’s Ridgecrest earthquake sequence destabilizing nearby faults, Caltech scientists say in a new study released in the journal Science on Thursday.
In the modern historical record, the 160-mile-long Garlock fault on the northern edge of the Mojave Desert has never been observed to produce either a strong earthquake or even to creep — the slow movement between earthquakes that causes a visible scar on the ground surface. But new satellite radar images now show that the fault has started to move, causing a bulging of land that can be viewed from space.
“This is surprising, because we’ve never seen the Garlock fault do anything. Here, all of a sudden, it changed its behavior,” said the lead author of the study, Zachary Ross, assistant professor of geophysics at Caltech. “We don’t know what it means.”
The observations reported are another piece of evidence that illustrates a widely persistent myth that circulates in California and beyond — that quakes like the Ridgecrest temblors are somehow a good thing that makes future quakes less likely. In fact, generally speaking, earthquakes make future earthquakes more likely. Most of the time, the follow-up quakes are smaller. But occasionally, they’re bigger.
The creeping illustrates how the Ridgecrest quakes that began on the Fourth of July have destabilized this remote desert region of California between the state’s greatest mountain range, the Sierra Nevada, and its lowest point, Death Valley.
Not only has the Garlock fault begun to creep in one section, but there’s also been a substantial swarm of small earthquakes in another section of the fault, and two additional clusters of earthquakes elsewhere — one south of Owens Lake and the other in the Panamint Valley just west of Death Valley.
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