A magnitude 5.6 earthquake struck Northern California on Wednesday morning, with an epicenter approximately seven miles northwest of Willits in Mendocino County. The event caused minor injuries, power outages, and localized damage. The U.S. Geological Survey (USGS) initially reported the magnitude as 6.0 before downgrading it to 5.6.
Event Details
The earthquake occurred at 8:10 a.m. PT at a depth of about five miles. The USGS reported at least three aftershocks within the first hour, all under magnitude 2.7. As of the latest reports, more than a dozen aftershocks have been recorded, most below magnitude 2.5.
Seismologist Lucy Jones stated that this is the strongest earthquake in the region since 1940 and noted that aftershocks are likely but expected to be small.
The earthquake was felt across parts of the Bay Area, including Sonoma, Walnut Creek, and San Jose.
Impact and Damage
Injuries
- Mendocino County spokesperson Heather Rose reported that hospitals had treated some injuries, though no specific details were provided.
- The Mendocino County Executive Office confirmed injuries but no fatalities.
- The California Governor's Office of Emergency Services (Cal OES) stated it had received no damage or injury reports.
Power and Utilities
- Power outages affected over 6,000 to 8,000 customers, with power restoration expected around 6 p.m. local time.
- PG&E outage maps showed power loss across the community.
- Water outages and water line breaks were reported.
- Downed power lines and possible gas leaks were investigated.
Structural Damage
- Reports include cracked walls in some buildings.
- Grocery stores in the area were closed due to damage or had limited operations.
- Photos show items knocked off shelves and a speaker shifted off a ledge.
- Video from a Lake County grocery store shows items falling during the shaking.
- Damage assessments are ongoing. Early reports from state Sen. Mike McGuire indicated no major damage to public infrastructure such as hospitals or sewer systems in Ukiah or Willits.
Emergency Response
- Cal OES reported that nearly 657,000 earthquake early warning alerts were sent via the MyShake App.
- Governor Gavin Newsom was briefed and is coordinating with emergency officials.
Geological Context
The earthquake occurred on a strike-slip fault line that runs through Mendocino County and into northern Sonoma County, according to meteorologist Heather Waldman. The fault experiences approximately 8 millimeters of movement per year, and pressure release results in earthquakes.
The epicenter is located in a relatively unpopulated area of Mendocino County, about 50 miles east of Fort Bragg and 140 miles northeast of San Francisco.
Background
The area has experienced smaller earthquakes earlier this year. Mendocino County is not located on a major fault line, according to seismologist Lucy Jones.