One of more than 1,700 seismic events detected near Helena so far this year, a 5.8 magnitude earthquake centered six miles south of Lincoln on July 6 was the biggest ever recorded west of the Continental Divide in Montana and the strongest to hit the state in more than 40 years.
The U.S. Geological Survey recorded at least nine tremors within an hour of the initial 12:30 a.m. quake, and they ranged in magnitude from 4.9 to 3.1.
Despite the late hour, Lewis and Clark County's 911 dispatchers received 257 calls from people asking about the earthquake within about 15 minutes of the initial activity.
News of the earthquake and its aftershocks also blew up on social media, as people from Missoula to Billings and some surrounding states described what they saw, felt and heard. The earthquakes were strong enough to knock items off of walls and shelves as far away as Helena and Missoula, cause a temporary power outage in Lincoln and cause a gas leak in Helena.
In the small community of Lincoln, which was hit the hardest, business owners, volunteer firefighters and neighbors gathered later that morning to survey the damage and help clean up broken glass and spilled products at the Wheel Inn Tavern, D&D Foodtown grocery store and other local businesses. Though some businesses suffered a financial loss, no serious damages or injuries were reported.
The earthquake occurred near a fault line that was not previously mapped by seismologists, and the exact causes of Montana’s seismic activity remain in debate.
“If you look globally, it is interesting and unusual to have a seismic belt such as we have form far away from an active plate tectonic boundary,” Mike Stickney, seismologist at the Earthquake Studies Office of the Montana Bureau of Mines and Geology on the Montana Tech Campus in Butte, told Lee Newspapers at the time.