The California earthquake sequence has triggered a failure that has been inactive for the past 500 years, say geophysicists at the California Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory.
US researchers conducted an investigation into the causes and mechanisms of a series of earthquakes that struck southern California in July this year.
"It turned out to be one of the best documented earthquake sequences in history," said Zachary Ross, assistant professor of geophysics and lead author of the scientific paper, published in the journal Science.
The Ridgecrest quake ruptures ended within a few kilometers of the Garlock Fault, a major geological fault extending over 300 kilometers from the San Andreas Fault to Death Valley, NASA's Jet Propulsion Laboratory reports. in statement.
The fault has remained relatively inactive for the past 500 years, but the strain exerted by the seismic activity has caused it to start moving slowly and sliding two inches since July.
At the same time, research provides evidence that major earthquakes can occur in a more complex way than is commonly thought.
The largest earthquakes are considered to be caused by the rupture of a major geological fault, and the maximum magnitude is mainly related to the length of the fault.
However, the Ridgecrest earthquake sequence involved about 20 previously unknown small faults that intersect in a geographically complex and geologically young zone.
"We cannot assume that major faults are what dictate the seismic threat, if many smaller faults can come together to create large earthquakes," Ross said.
Research shows that we still know little about earthquakes and the prediction of seismic risk.
. (tagsToTranslate) California Earthquakes (t) Geological Fault