The USGS reported a 4.4 magnitude earthquake hit at 12:08 p.m. about 3.7 miles northeast of Lima Tuesday, closely followed by a 3.5 magnitude earthquake at 12:11 p.m., about seven miles northeast of the town.
The USGS then recorded three more earthquakes, or aftershocks, in the area Tuesday night and Wednesday morning, all about six miles northeast of Lima.
The first 2.6 magnitude quake was 6.5 miles in depth, while the second 3.4 magnitude earthquake was 6.6 miles beneath the surface. The last 2.6 earthquake was at a depth of 6.9 miles.
Geologist Michael Stickney told MTN News there were reports of Butte residents feeling Tuesday’s earthquakes, while some people in Lima described them as a bomb or an explosion.
One of Tuesday’s earthquakes occurred along a fairly active fault called the Centennial Tectonic Belt, but it hasn’t experienced a major quake in decades.
“The really significant earthquake that occurred in this zone was the 1983 Borah Peak Idaho earthquake, which had a magnitude of 6.9. It resulted in two fatalities in Challis and caused significant damage,” Stickney said.
The strongest earthquake to hit Montana in more than a decade happened near Lincoln in July 2017.