Recent earthquake swarm at Tahoe triggers talk among seismologists about potential for bigger ones
Submitted by Arianna Schmidt on Tue, 06/15/2021 - 2:35pm
Earthquakes in Lake Tahoe and the greater area have been on the larger side of the seismology scale since spring 2020 as frequency of the quakes have also increased.
Residents spanning the length of Carson City felt the 3.2 magnitude quake last March, which originated just northeast of Indian Hills according to the United States Geological Survey.
The University of Nevada Seismology Laboratory reported a 3.9 magnitude quake near Glenbrook last April, which shook residents from Carson City to Meyers in South Lake Tahoe. Later data reported smaller quakes in the area at 2.5, 1.9, and 2.8 magnitudes respectively.
The Stateline fault, as local Tahoe seismologists have dubbed it, has shaken with several dozen quakes since April of this year. Consequently, one big question arises: Are these aftershocks of something deeper or foreshocks of a bigger quake to come?
May 2021 recorded various quakes around the Lake Tahoe region, each major one being roughly two weeks apart. KRNV Channel 4 in Reno reported a 4.7 magnitude quake on May 6 just north of Truckee, Calif.
A quake on May 17 shook at a 3.4 magnitude near Tahoe City, as recorded by the UNR Seismology Laboratory. May 28 brought an even bigger shake, recorded at a 4.3 magnitude by the UNR lab in the middle of Lake Tahoe.
Dr. Graham Kent, director and professor in the UNR Seismology Laboratory, said most people think of San Andreas as the epicenter for quake-causing faults.
However, most of the major faults range from Echo Summit to Fallon, with half to 1/3 of San Andreas quakes coming through this area.
"It’s a big deal,” Kent said.
According to Kent, only time will tell when the next big underground rupture will occur.
“We have two fault lines that haven’t ruptured in an average of 4,500 years in Lake Tahoe, 7,800 years ago and 1,100 years ago,” Kent said. “A common sense person would say we’re due.”
While all of this data may lead to conclusive information on what is to expect seismically of Lake Tahoe, there is a possibility of another kind of natural disaster: tsunami waves.
Steve Bohlen, a Geological Survey geologist in California, told CBS Sacramento in May that he has recently observed a rise in earthquake activity around Lake Tahoe. The lake, as Bohlen pointed out, sits directly on a fault line near Stateline Point and Incline Village.
"There is a tsunami hazard around Lake Tahoe," Bohlen said in an interview. Although ultimately unlikely, a 7 magnitude earthquake within the lake would be enough to trigger the effects of tsunami-like waves, according to Bohlen.
Despite the unlikely reality of a lake tsunami triggered by a big shake, Kent said the Stateline fault is not capable of a quake magnitude 6 or above. A 6 on the seismograph isn’t scientifically large enough for tsunami-like waves.
“Whenever hitting the ends of large fault lines people get nervous that things are getting bigger,” Kent said. “Seismologists talk to each other after these quakes to share and analyze.”
While prevention of an earthquake may not be feasible, mitigation of losses is. Kent advises people to pay attention to strong shaking if they are on the beach, and to move to higher ground immediately.
“Education and awareness is key,” Kent said. “Large events will produce a 30 foot tsunami and can have subterranean landslides without a quake that could cause a tsunami too.”
Kent said faults aren’t perfect, they’re messy. Therefore, recent data can’t be certain in determining the next big earthquake, even one to rock Lake Tahoe into producing tsunami-like conditions.
— Paula Peterson of SouthTahoeNow.com contributed to this report.
