THE U.S. GEOLOGICAL SURVEY ON SATURDAY AFTERNOON UPGRADED THIS QUAKE’S MAGNITUDE FROM 4.3 TO 4.5. 

COBB, Calif. – A 4.5-magnitude earthquake was reported early Saturday morning near The Geysers geothermal steamfield.

In its preliminary report, which was reviewed by a seismologist, the U.S. Geological Survey said the quake occurred at 2:23 a.m.

The quake's epicenter was located three miles east of The Geysers, three miles southwest of Cobb, four miles west northwest of Anderson Springs and 24 miles north of Santa Rosa at a depth of 1.7 miles, according to the report.

It was quickly followed by more than a dozen smaller aftershocks, the largest of which was 2.3 in magnitude, according to the U.S. Geological Survey.

Several residents of the Cobb area reported on Lake County News' Facebook page that they had been awakened by the quake, which some also reported seemed to last longer than usual.

Within a half-hour of the quake taking place the U.S. Geological Survey had received more than 70 shake reports from 23 zip codes.

Responses came from Clearlake, Hidden Valley Lake, Kelseyville, Lower Lake and Middletown, as well as areas in Napa and Sonoma counties, and the Bay Area, with responses coming from as far away as Sacramento and San Francisco.

The last time a quake of similar magnitude was reported in the Cobb area was on Feb. 12, when a 4.3-magnitude quake – also located three miles east of The Geysers – occurred, as Lake County News has reported.

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