By Rob Chaney of the Missoulian
A small earthquake rocked houses from Seeley Lake to Ovando just after 10 p.m. Sunday, according to U.S. Geological Survey data.
The earthquake had two shockwaves, according to Mike Stickney at the USGS office in Butte. The foreshock measured magnitude 3.1, while the second arrived 25 seconds later with a 3.7 magnitude. Both quakes were centered between Black and Alloy mountains in the Bob Marshall Wilderness, about 21 miles northeast of Seeley Lake. Their epicenter was nine miles beneath the Earth’s surface.
Brad Weltzien said his family felt the bump at their house just south of Seeley Lake.
“It was real quick – like one huge blast of wind, but it was still as can be last night,” Weltzien said. “You could hear lots of cracks from the house, but it didn’t move anything. We didn’t feel it shake so much as hear the house make noise.”
Montana Fish, Wildlife and Parks biologist Jay Kolbe was camped within a mile of the epicenter on Sunday in the Danaher Meadows area, close to the headwaters of the South Fork Flathead River. He was back in Seeley Lake Sunday evening and didn’t feel the quake. But he said the area looked prime for earthquake activity.
“It’s pretty tortured country,” Kolbe said. “There are some slides along the Dry Fork and North Fork of the Blackfoot. I don’t know if they’re seismic-related, but the whole Bob is that overthrust geology. It’s not as dramatic as on the east front, but it’s beautiful.”
Stickney said the area has recorded a lot of small quakes over the past decade.
“It’s part of the Overthrust Belt, and then it was cut up by later, younger faults,” he said. “There’s some spectacular geology back there.”
I actually felt this earthquake. At first I thought I might have been dreaming. It sounded like extremely loud thunder for a few seconds and then the ground began to shake. We were probably 10 miles from the epicenter when it happened.