Chance of big San Andreas earthquake increased by Ridgecrest temblors, study suggests
A new study suggests that last year’s Ridgecrest earthquakes increased the chance of a large earthquake on California’s San Andreas fault.
The study, published in the Bulletin of the Seismological Society of America on Monday, says there is now a 2.3% chance of an earthquake of magnitude 7.5 or greater in the next 12 months on a section of the 160-mile-long Garlock fault, which runs along the northern edge of the Mojave Desert.
That increased likelihood, in turn, would cause there to be a 1.15% chance of a large earthquake on the San Andreas fault in the next year.
Those odds may seem small. But they’re a substantial jump from what the chances were before last year’s Ridgecrest, Calif., earthquakes, whose epicenters were about 125 miles northeast of downtown L.A.
The new odds mean a large quake on the Garlock fault is now calculated to be 100 times more likely — rising from 0.023% in the next year to 2.3%.
And the chance of a large quake on the San Andreas has roughly tripled, from 0.35% in the next year to 1.15%, said Ross Stein, a coauthor of the study and the CEO of Temblor, a catastrophe modeling company in the Bay Area that has built a free earthquake hazards app for smartphones.
One plausible scenario involves the
Ridgecrest, Calif., quakes triggering a large temblor on the
Garlock
fault, which then triggers a seismic event on the San Andreas. The
chances of such an event
happening are small. Another plausible
scenario, not mapped, involves a rupture of faults southeast of the
Ridgecrest quakes.
(Jon Schleuss / Los Angeles Times)
“What has been actually happening in the real world is
quite different than what
we thought was a plausible scenario back at
the time in ’92,” Hudnut said.
....MUCH MORE
Ditto.
