4.2 quake hits Geysers area

Officials say temblor, 6 aftershocks likely not a harbinger of more seismic activity
August 5, 2003

By KATY HILLENMEYER
THE PRESS DEMOCRAT

A predawn earthquake shook northern Sonoma County Sunday near the Geysers geothermal area 25 miles north of Santa Rosa.

Centered four miles southwest of Cobb, the 4.2-magnitude temblor occurred at about 5 a.m. and was followed by six small aftershocks, according to the U.S. Geological Survey.

No injuries or serious problems were reported to law enforcement personnel in Sonoma, Napa, Lake and Mendocino counties.

The quake's impact was limited because of its shallow depth of about one mile, said David Schwartz, chief of the San Francisco Bay Area Earthquake Hazards Project for the U.S. Geological Survey. He said it should not be considered a precursor of seismic activity along the region's major faults.

"This doesn't say anything about the likelihood of something major occurring on any of the other faults in the region," Schwartz said. "It's very, very typical of the kind of small-scale earthquake activity that occurs in the Geysers."