Three earthquakes up to magnitude-4.2 and nearly a half-dozen aftershocks jolted northern Idaho, with residents from Washington state to Montana saying they felt the tremors.
A Bonner County emergency dispatcher in Sandpoint said Friday morning that no injuries or damage were reported. The U.S. Geological Survey says a magnitude-4.1 quake hit first, around 7:32 p.m. Thursday, centered 30 miles northeast of Hayden.
"It was crazy, the whole house was shaking," said Charity Hadley, 37, of Sagle, who was outside on her deck with her dog, Bella. "She was running around the yard and barking and looking around like, 'What is this?'"
She said nothing was damaged in the house during the quake that she estimated lasted several minutes.
A second quake of magnitude-4.2 struck a little more than three hours later, waking up Hadley and her dog. That quake was centered 38 miles northeast of Hayden. Then, a magnitude-3.3 temblor hit at 1:28 a.m. Friday in the same area.
Also Friday, a magnitude-6.1 earthquake struck British Columbia's north coast, but a tsunami was not expected and no injuries or damage were reported.
After the Idaho temblors, hundreds of people logged onto the Geological Survey's National Earthquake Information website to report feeling them.
Mike Stickney, senior research geologist at the Montana Bureau of Mines and Geology based in Butte, Montana, said four aftershocks of up to magnitude-2.5 occurred after the first quake and another small aftershock followed the second quake.
He said the shaking was almost certainly caused by a slip on a fault, though there are no known active faults in the area. However, there are many old faults—millions of years old that occurred with the formation of the Rocky Mountains—that likely caused the quakes, Stickney said.
The Lucky Friday Mine, a silver mine and one of the nation's deepest at about a mile, is about 60 miles from where the quakes struck, but they weren't felt there and work was going on as usual, said Mike Westerlund of Hecla Mining Co. A small earthquake closer to the mine in February briefly slowed production.
Stickney said he had no reason to believe the recent quakes might lead to something larger but had no guarantees.
"It's not one of the more seismically active regions in Idaho," he said. "But as this well-proves, nowhere in the state is immune from the possibility of earthquakes."
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