Since a magnitude-5.3 quake hit near Soda Springs last weekend, more than 100 smaller quakes have continued to pummel the region till today, Sept. 6.
Experts said the quakes could continue for about another week but they are unsure exactly when it will all end, NBC reported.
The magnitude 5.3 hit about 6 p.m. last Saturday and there were no immediate reports of injuries or damage to structures. Earthquakes with a magnitude of 5 can cause property damage but not have any severe impacts.
Officials said 17,000 people reported feeling the magnitude 5.3—some felt it in Salt Lake City in Utah, some 170 miles away.
According to the Idaho State Journal, the quake was the largest to hit the area in years.
The latest quake struck about 5 miles from Soda Springs at 12:37 a.m. on Sept. 6 as of this writing—it had a magnitude of 4.5 according to the U.S. Geological Survey. All the additional quakes following the larger Saturday one have been below magnitudes of 4.5, hovering between 4.0 to 4.5.
A geophysicist with the U.S Geological Survey told NBC that the quakes would likely stop soon.
“They can go on for days or weeks, and they’ll get smaller in size and frequency,” John Bellini told NBC.
Bellini noted that forecasting the next earthquake risk can be hard to calculate.
“Do we expect a larger one? No, we don’t,” he said.
“You don’t have earthquakes every day like in California—they’re feel-able just a few times a year in Idaho,” Bellini said. “It’s harder to make generalizations like that in areas that don’t have as much seismicity. Idaho has had larger earthquakes in the past, but how often they repeat is not known.”
A Soda Springs resident JoAnna Ashley told NBC that when the biggest quake hit she grabbed onto her shaking fridge and saw a bottle of tiki torch fuel on top of it wobble to the edge. Her children grabbed on to her during the tremors.
“They didn’t scream, but were all, ‘Momma, what’s happening?’ in that worried voice,” Ashley told NBC.
“It kind of became commonplace. You’d be sitting there in the chairs, everyone talking, and all of a sudden you’d start to see the water shaking inside the bottle,” she said.
According to Ashley, the current quakes feel unusual because of the size and frequency, she experienced other earthquake swarms in the region.
“This is unprecedented for everybody. But if they say a bigger one is unlikely, then I think we’ll all be fine,” Ashley told NBC. “The only concern is that we’ll get a big enough one to do damage—most of us here don’t have earthquake insurance.”
The largest earthquake ever recorded in Idaho was back in 1983—the Borah Peak earthquake, which had a magnitude of 6.9. That’s about 250 times stronger and 40 times larger than this most recent Saturday quake, according to the U.S. Geological Survey.