Major California Fault Line Moves for First Time in 500 Years


A MAJOR FAULT LINE IN Southern California capable of producing a magnitude 8 earthquake began to move for the first time in 500 years.

study published in the journal Science on Friday by geophysicists from the California Institute of Technology and NASA’s Jet Propulsion Laboratory found that the Garlock fault, which runs east to west for 185 miles from the San Andreas Fault to Death Valley, has shifted 0.8 inches since July. It marks the first documented movement of the fault in the modern historical record.


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The fault’s movement was triggered after Southern California’s largest earthquake sequence in 20 years, which began on July 4. The earthquakes in Ridgecrest, California, started with a magnitude 6.4 foreshock, followed by a magnitude 7.1 quake almost 34 hours later. More than 100,000 aftershocks were recorded, according to a press release from the California Institute of Technology.

Satellite images show the ruptures that reached the surface, a process called fault creep, which began after the earthquakes. The sequence, the study states, is one of the most well-documented earthquake series in history.

The earthquakes sent ruptures through a series of interconnected faults in the region, straining the Garlock fault. Zachary Ross, author of the study and assistant professor of geophysics at Caltech, said in the release that the foreshock triggered rupturing in surrounding faults.

“We actually see that the magnitude-6.4 quake simultaneously broke faults at right angles to each other, which is surprising because standard models of rock friction view this as unlikely,” Ross said. “It is remarkable that we now can resolve this level of detail.”

About 20 previously unknown crisscrossing faults were involved in the summer earthquake series, prompting scientists to believe that earthquakes are a more involved process than just a rupture on a single fault line