A 3.6 magnitude earthquake struck just north of Great Falls, Montana, at 7:40 a.m. Friday, September 18, 2026. The U.S. Geological Survey placed the quake about 3.1 miles northwest of Black Eagle and about 17.2 miles deep.
It was the first earthquake in several months after a series earlier in 2026, and the new shake fit the same pattern. The survey said the region had already seen a 4.2 magnitude quake on January 29, followed later that day by a 2.7 magnitude event, then 3.2 magnitude shaking on January 31, 3.7 magnitude shaking on February 12 and 2.8 magnitude shaking on February 26.
Great Falls and Black Eagle
The quake was shallow enough to be felt in the area around Great Falls and Black Eagle, but the documented result stayed limited to shaking. Nearby residents were affected, yet no injuries, serious damage or infrastructure impacts were reported in any of the incidents described by the U.S. Geological Survey.
That record leaves the September event in the same category as the earlier ones: a noticeable jolt, but not one that produced a public safety response in the facts provided. The sequence also points to a continuing cluster rather than a single isolated shock.
U.S. Geological Survey sequence
The September quake was described as probably an aftershock of the larger initial quake from January 29. The four smaller quakes earlier this year were also aftershocks of that 4.2 magnitude event, which makes the September reading part of the same chain rather than a separate episode.
For people in the area, the practical takeaway is narrow but useful: the quake was strong enough to register clearly, but the reported effects stopped at the shaking itself. Why the earthquakes near Great Falls have been occurring in this sequence was not explained in the facts provided.
