Earthquake Strikes Sonoma County Just Prior To Larger CA Quake

SONOMA COUNTY, CA—The U.S. Geological Survey gave a preliminary magnitude reading of 5.8 for an earthquake Thursday in northern Sonoma County. The reading was later downgraded to 4.1. The earthquake followed an even larger one with a preliminary reading of 7.0 just off the coast of Humboldt County, California.

According to the initial USGS ShakeMap, the epicenter of the Sonoma County quake was 5.8 miles northwest of Cobb and 6 miles west of The Geysers in northeastern Sonoma County.

Patch readers with 707 area codes reported receiving earthquake alerts on their cell phones shortly before the Sonoma County quake, which struck at 10:47 a.m.

The 7.0 quake struck 45 miles southwest of Eureka, California, three minutes earlier and prompted a tsunami warning that stretched north to Oregon and south to the Bay Area and Santa Cruz.

• SEE MORE: Tsunami Warning Issued After Large Earthquakes Shake Northern CA

Authorities said the tsunami would reach Sonoma County at 11:45 a.m.; however, the warning was later canceled.

"Many community members received the earthquake alert on their cell phones, followed by a Tsunami Warming alert," the Santa Rosa Fire Department said. "There were no reports of any damage locally from the earthquake. The Tsunami Warning was subsequently canceled. The State and Federal early alert and warning systems worked as designed."

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Several temblors followed. At 10:48 a.m., a 2.5-magnitude quake was recorded near Cobb and The Geysers.

This is a developing story; refresh the page for updates.

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