Updated 10:20 p.m. Jan. 29

A 4.2 magnitude earthquake shook the Great Falls region around 12:41 p.m. Jan. 29.

According to the U.S. Geological Survey, the epicenter was about eight kilometers northeast of Black Eagle at a depth of 22.5 kilometers.

A 2.7 magnitude aftershock was recorded at 5:46 p.m. about five kilometers north-northwest of Malmstrom Air Force Base at a depth of 16.1 kilometers, according to USGS.

As of about 5 p.m., there had been no aftershocks of magnitude 3 or higher, which are strong enough to be felt nearby, according to USGS.

The USGS estimates the chance of more aftershocks within the next week until Feb. 5:

• 20 percent chance of magnitude 3 and above aftershocks and it is most likely that 0 to 4 of these will occur
• 4 percent chance of magnitude 4 and above aftershocks and it is most likely that 0 to 1 of these will occur
• 3 percent chance that this earthquake becomes a foreshock to a larger earthquake (magnitude 4.2 or greater), such an earthquake is possible but with a low probability

The USGS recorded 896 responses to their Did You Feel It tracker.

Malmstrom Air Force Base said that the earthquake caused no impact to the base and all operations were proceeding normally.

Immediately after the event, airmen conducted “thorough inspections across the entire base and the missile complex. We have found no damage to any of our equipment or facilities, and the security of the missile complex remains fully intact,” Malmstrom said in a statement. “The safety of our airmen, their families, and our local community is our highest priority. We will continue to monitor our systems to ensure the continued safety and security of the base and the surrounding area.”

NorthWestern Energy said that because the epicenter was close to the Big Sandy Pipeline, their Gas Transmission Services team was in the field inspecting above‑ground facilities and patrolling the pipeline to make sure the system continues operating normally.

Gas Control is also reviewing system pressures and flows to confirm everything looks normal, according to the company.

NWE’s hydro team also completed initial checks at the Great Falls sites and no immediate impacts were reported.

Operators began thorough inspections and walkdowns, following their dam safety protocols, according to NWE.

Other NWE responses to the earthquake include:

• team members from Cut Bank are inspecting above‑ground natural gas structures between Great Falls and Floweree
• team members from Great Falls are inspecting above-ground natural gas structures in Great Falls
• line patrol crews from Havre are patrolling the Big Sandy line from Fort Benton to Great Falls
• a detailed inspection is underway within 10 miles north and south of the earthquake’s epicenter
• hydro operators are conducting full site walkdowns and safety checks at Great Falls facilities
• crews are inspecting the Spion Kop wind facility though it’s further from the epicenter
• gas control has reviewed current and historical gas pressures and flows to ensure there are no fluctuation points on the transmission system

The Great Falls Police Department wrote on their Facebook page that “we understand something like your house shaking may feel like an emergency but, when 911 is misused it could cause a delay in getting help to someone truly in need.”

When the earthquake hit, 911 was fully staffed with four dispatchers, plus the director and deputy director.

Multiple lines are dedicated to incoming 911 calls and on average, dispatchers get seven calls in an hour.

From 12:40-1 p.m. Jan. 29, there were 73 calls to 911, according to GFPD, and “for every one of the 911 calls, a dispatcher determined there was no incident requiring a police, fire, or medical response.”

There were at least 29 calls to the GFPD non-emergency number.

911 calls are prioritized over non-emergency calls and will be answered by a dispatched if the caller stays on the line, according to GFPD, so several callers to the non-emergency number received a recorded message.

• check on those closest to you first
• check online resources for information, including social media
• check your structures, paying close attention to utility connections and structure stability
• call 911 if someone is injured or in imminent danger, if a structure is damaged and liable to collapse, if a fire started, if a gas line is leaking, if electrical wires are down or arcing, if flooding or looting is happening, and anything else that requires a lights and siren response from police, fire, or medical personnel