Sizable Earthquake Rattles Bay Area Overnight: Did You Feel It?

NORTH BAY, CA — An early-morning earthquake and aftershock shook parts of the North Bay early Thursday morning east of Cloverdale, according to the U.S. Geological Survey.

A 4.2 magnitude earthquake hit seconds after midnight just under 8 miles east of Cloverdale and the Geysers.

The quake was widely felt in Kelseyville, Cloverdale, Healdsburg, Lakeport, and Santa Rosa, and in southern Mendocino and western Lake counties. Shaking was also reported from San Francisco to Pleasanton.

"Pretty good shaker a few minutes ago near Cloverdale - preliminary 4.4 magnitude. No early reports of damage or injuries," wrote Sen. Mike McGuire on Facebook.

That one was followed seconds later by a 2.7-magnitude aftershock at 12:07 a.m.

The Bay Area has been an active region for quake activity over the last month with swarms reported in the San Ramon area. In the last month of the year, San Ramon saw about 150 earthquakes, its second highest number in nearly 50 years, according to the San Francisco Chronicle.

San Ramon and Cloverdale sit along the Calaveras Fault, and several micro-faults along the main fault result in swarms of quakes. When fluids like water or gas move through a complex web of cracks in tiny faults, this can trigger many dozens of small quakes in quick succession.

In addition to the Calaveras Fault, the San Andreas and Hayward faults also run near Cloverdale.

SEE ALSO:

• Earthquake Strikes San Ramon Saturday Morning
• Earthquake Swarm Rattles San Ramon For The Third Time This Week
• Why Does San Ramon Get So Many Earthquakes?
• 5 Things Most People Don't Know About Earthquakes
• Earthquake Swarm Rattles Bay Area Overnight. USGS Weighs Chances Of Bigger Ones To Come
• Bay Little Known Bay Area Fault Could Trigger The Next Big One
  
• Are You Living on a Fault Line?
• Fault Capable Of 8.0 Quake Awakens Thanks To Ridgecrest Temblors
• Long Overdue Eastern Sierra Quake Could Rock Reno, Lake Tahoe

Patch Stafer Michael Wittner contributed to this report.