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Quake hits Mendocino
A magnitude 5.6 earthquake struck Mendocino County on Wednesday morning at 8:10 a.m. Pacific Time, centered about seven miles north of Redwood Valley near Willits, according to the U.S. Geological Survey.
The quake knocked out power and water service for thousands, with the Mendocino County Executive Office saying there have been some injuries but no deaths.
CBS News reported that USGS also recorded a preliminary 2.5-magnitude earthquake about seven minutes later, followed by likely aftershocks measuring 2.7 and 2.6 about an hour later.
ABC News said the shaking was felt across parts of the Bay Area, with reports from Sonoma, Walnut Creek and as far south as San Jose, and that Governor Gavin Newsom’s office said the governor has been briefed and is coordinating with emergency officials.
Alerts, officials, residents
ShakeAlert notifications went out across Northern California, and CBS News said residents received push alert notifications from ShakeAlert, a USGS early warning system for California, Washington and Oregon.
Sacramento Bee quoted seismologist Dr. Angie Lux saying, "The earthquake early warning system is a very fast system," and described how Sacramento received alerts even if residents felt little or no shaking.
In Mendocino County, KRON4 said the county reported some injuries but no deaths, and a KRON4 viewer in Lake County described the quake as lasting around seven seconds.
KTVU quoted UC Berkeley Seismology Lab research scientist Amy Williamson saying the quake was "the largest quake on this fault, which is an extension of the Hayward Fault, in 75 years," while also describing cracked home structures, knocked-out power, broken water pipes, and fallen pictures and vases.
Aftershocks and risk
As emergency crews assessed damage, the National Tsunami Warning Center said there was no tsunami warning, advisory, watch or threat from the earthquake, while Mendocino County officials said they were not aware of any major damage and crews were continuing to assess the area.
“Along California's northern coast, where three massive tectonic plates meet, intense but invisible seismic activity has just revealed its secrets”
The Sacramento Bee reported that Lux said there is a "very, very, very small chance" Wednesday’s earthquake was a foreshock to a larger event, and NBC Los Angeles said the quake was followed by a magnitude-2.5 aftershock.
Beyond the immediate quake response, Génération NT described USGS seismologists mapping the Mendocino triple junction using thousands of tiny earthquakes and said the discovery published in Science "radically changes our understanding" of the region.
Génération NT also quoted seismologists like Roland Burgmann of UC Berkeley saying the new geometry makes a domino effect more likely, with a major earthquake on the Cascadia fault more likely to trigger a rupture on the San Andreas fault.
