“We’re starting to nail down specifically where they happened,” said Ken Sprenke, a professor of geophysics at University of Idaho.
Sandpoint is at the northern edge of a large seismic zone running from Helena, Montana, to Coeur d’Alene. It sits atop what’s known as the Hope Fault, Sprenke said.
Inland Northwest quakes are mysterious, he said, because they don’t involve plate tectonics. Nor would they be related to oil fracking on the Great Plains, he added.
UPDATE: A third earthquake, magnitude 3.3, was reported eight miles east-southeast of Sandpoint at 1:28 Friday morning.
Two earthquakes shook Sandpoint and much of North Idaho Thursday night, but there was little damage.
The U.S. Geological Survey reported a magnitude 4.1 earthquake at 7:32 p.m. about 14 miles southeast of Sandpoint, east of Lake Pend Oreille, just south of Kilroy Creek.
The second quake was recorded at 10:43 p.m. The 4.2-magnitude quake’s epicenter was within Lake Pend Oreille, just west of Hope.
A Bonner County dispatcher said emergency responders received no immediate reports of damage from the second quake. The only report of damage after the first event was about downed trees near Whiskey Rock, not far from the epicenter.
For about five seconds Thursday evening, glasses and bottles at the Cabinet Mountain Bar and Grill in Clark Fork, Idaho, began to clink.
“It was just a lot of shaking,” said Torrie Straley, a bartender. “The whole entire bar shook.”
The restaurant is the only business open late in Clark Fork, and many residents soon began calling to find out what occurred. Some reported to Straley that pictures fell off their walls.
The bar felt the second quake, too, Straley said. Shaking seemed less severe, but it lasted longer, maybe 10 to 15 seconds, she said.
Both quakes were widely felt in the county, and Bob Howard, Bonner County’s emergency management director said the emergency manager in Thompson Falls, Montana, noticed the shaking, too. Howard felt the quake in his home in Cocolalla.
“I was sitting here and I couldn’t figure out what was going on,” he said.
The Bonner County 911 center was inundated with calls immediately following the quake, he said.
“We have earthquake faults in our county, but it’s not prone to earthquakes,” he said.
But earthquakes near Sandpoint are not unheard of. A magnitude-5 quake shook the town in 1942. Idaho experienced two of the most destructive quakes in the lower 48 states in the 20th century. According to previous news reports, those were the 1959 Hebgen Lake earthquake, a magnitude 7.5 temblor centered 10 miles across the state line in Montana, and the 1983 Borah Peak quake, magnitude 7.3, which killed two people and caused millions in damage in Challis and Mackay.
It was $1 beer night Thursday at Eichardt’s Pub in downtown Sandpoint. So the bar was pretty full when the first quake struck.
But struck might be an overly strong word.
“The bar stool jiggled,” said Joshua Burt, whose friend quickly pulled out a cellphone and pinpointed the earthquake’s data on the U.S. Geological Survey’s website.
“We were one of 26 earthquakes in the world,” he said noting the day’s count at that point. “We felt pretty privileged to be part of it.”
The second quake was the 28th of the day.
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