How to resolve AdBlock issue? KELSEYVILLE, Calif. – A series of small earthquakes that occurred in the Soda Bay area earlier this week caused some county residents to wonder about what triggered them.
Lake County residents are familiar with earthquakes, especially due to the numerous small and moderately sized quakes that are reported on a regular basis in The Geysers geothermal steamfield in the Cobb area.
However, the quakes near Kelseyville – peaking with a 2.8-magnitude quake that occurred on Tuesday afternoon – don’t fit into the normal local earthquake pattern, and Lake County News received a number of comments and inquiries from readers about the reasons for the quakes.
David Oppenheimer, a seismologist with the US Geological Survey in Menlo Park, offered some explanations.
“At this point we're just seeing a little flurry of earthquakes,” said Oppenheimer.
The quakes have been centered to the southeast of Mt. Konocti. “There's a whole bunch of mapped faults in the area that are active faults,” Oppenheimer said.
In particular, Oppenheimer said the Konocti Bay fault zone runs right through the area where the quakes occurred.
While the quakes that most people felt occurred on Tuesday, Oppenheimer said there has been a much larger group of the temblors.
Between 9:15 p.m. Monday and 12:19 a.m. Wednesday there were 14 quakes, Oppenheimer said, ranging from quakes of under 2.0 in magnitude up to the largest, 2.8.
The 2.8 and a 2.7 quake that preceded it received a total of 65 shake reports from around Lake County, with some coming in from the Bay Area and even Red Bluff, according to US Geological Survey data.
The quakes, Oppenheimer noted, tended to be shallow.
“They're not under the volcano, which is one of the first issues that would get our attention,” Oppenheimer said.
He was referring to the 300,000-year-old Mt. Konocti, the most prominent volcanic feature of the Clear Lake Volcanic Field, which includes a portion of Lake County and also is monitored by the US Geological Survey.
Oppenheimer said it's not uncommon to have more seismic activity in volcanic areas.
“We haven't seen anything that would lead us to believe that it's directly related to the volcanic system,” said Oppenheimer.
He said there have been other, similar instances of flurries of small quakes in that area.
Similar sequences were reported in 1975, 1983 and, most recently, in April of 2008, he said.
It’s likely the string of quakes will last a few days and then die off, he said. “We are aware of it and we're watching it.”
While there's no evidence of Mt. Konocti waking up, if the quakes start to take off, Oppenheimer said USGS will let the community know.
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