At least six earthquakes, including one with a preliminary magnitude of 4.2, shook the Lake Tahoe, Reno and Carson City area early on Friday, according to the U.S. Geological Survey.
The strongest one struck near the north end of the lake at Dollar Point, Calif., around 8:30 a.m. Pacific Daylight Time. There were no immediate reports of damage.
It came as Lake Tahoe’s resorts and tourist destinations prepared for a Memorial Day holiday that they hope will help lift the pall of the coronavirus pandemic and as legislators in Nevada’s capital met in early sessions to finish business before heading home for a long weekend. It was also the latest in a series of quakes that had seismologists watching the Lake Tahoe area closely, concerned that a bigger quake could create a tsunami.
The strongest quake on Friday was captured on video during a State Senate finance committee meeting on expanding Medicaid coverage.
“We are in the midst of an earthquake,” State Senator Chris Brooks said calmly as plexiglass could be seen moving.
In the reflection of the glass, a person is seen waving his or her hands. After a few minutes, Senator Brooks added, “All right, earthquake over.”
He joked to an assemblywoman, Michelle Gorelow, who was about to present to the committee, saying, “You really make an entrance.”
The earthquake also interrupted Senator Julia Ratti’s presentation to an Assembly Committee on Ways and Means hearing.
“So, that was fun — that’s a pretty good one,” Senator Ratti said. “Important business happening today, so we’re just going to keep going.”
The geological survey initially reported that the quake had a preliminary magnitude of 4.1, but that was revised higher. It followed an earlier one with a preliminary magnitude of 2.9, around 5 a.m. local time in the Dollar Point area, according to the U.S.G.S.
Later Friday morning, four more smaller earthquakes were reported, with preliminary magnitudes ranging from 2.7 to 3.1, according to the geological survey.
The 4.2 earthquake is part of an continuing sequence that began with a magnitude 3.7 earthquake on April 25, the Nevada Seismological Laboratory said on Twitter.
Dr. Graham M. Kent, the lab’s director, said there had been “many dozens” of earthquakes since then of magnitudes between 1 and 3.
He said such sequences were being closely watched by seismologists because if the current sequence continued, it could set off one of the two main fault lines beneath the lake, and that in turn could prompt a tsunami wave as high as 30 feet.
“The two fault lines of concern last ruptured 4,500 years ago, and are 1,000 years past their average occurrence or rupture,” Dr. Kent said.
Alex Hatem, a U.S.G.S. research geologist, said the 4.2 earthquake this morning occurred in a faulting area known as the Walker Lane that had “complex and closely spaced faults of different styles,” which made it difficult to determine which fault ruptured on Friday.
Within 20 minutes of the 4.2 earthquake, U.S.G.S. received more than 1,200 reports from residents who said they felt the quake.
Employees at the Obexer’s Boat Company, a marina on the west side of Lake Tahoe, felt the 8:30 a.m. quake shake their building.
Joanne Kilburn, the office and property manager, said she was sitting at her desk preparing for what would be a busy Memorial Day weekend when she felt it.
“The walls sort of cracked and the building shook,” she said. “I was concerned that I needed to get out.”
Other employees in the complex, which includes a store, pier shack and lodge, also felt the shaking, which lasted only several seconds.
“Our manager in the general store said he was watching the liquor wall because he was afraid that it was going to come down,” she said.
Ms. Kilburn said she had not felt the one about three hours earlier. “We have been having them over the past couple of months pretty regularly.”
An earthquake with a magnitude of 4.1 is strong enough to be felt but cause only minor damage, according to Michigan Technological University.
So far, it did not appear there had been damage to anything but people’s nerves.
The Carson City Fire Department said it had not been dispatched to any calls early Friday related to the earthquakes. The Reno Fire Department did not immediately respond to a request for comment on Friday.