The 3.1-magnitude earthquake occurred at 8:24 p.m. at a depth of 1.4 miles, as was centered two miles north of The Geysers, four miles west of Cobb and seven miles west northwest of Anderson Springs, according to the US Geological Survey.
A second earthquake, measuring 2.6 in magnitude, occurred 25 seconds later, to be followed by a third 10 seconds later that measured 1.8, US Geological Survey records showed.
Cobb resident Roger Kinney reported that the second earthquake felt near as big as the first and lasted longer.
Three more small quakes, two measuring 1.1 and one measuring 1.3, followed over the following three minutes. In all, 16 shakers followed the main one between 8:24 p.m. and midnight.
Besides several Cobb, the US Geological Survey reported that the 3.1-magnitude earthquake was reportedly felt in Kelseyville and as far away as Cloverdale.
Kinney said earthquakes in the seismically active area usually drop off in November and pick up again in April, so the quakes were a surprise, especially coming as closely apart as they did.
The last earthquake measuring 3.0 or above reported in Cobb, The Geysers or Anderson Springs took place Dec. 1 and measured 3.2 in magnitude.
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