A shallow magnitude 3.6 earthquake was reported near Great Falls, Cascade County, Montana, USA, in the morning.According to the United States Geological Survey, the quake struck on Friday, September 18th, 2026, at 7:40 am local time, at a shallow depth of 17 miles. Shallow earthquakes are felt more strongly than deeper ones because they are closer to the surface. The exact magnitude, epicenter, and depth of the quake might be revised within the next few hours or minutes as seismologists review data and refine their calculations, or as other agencies issue their reports.Our monitoring service identified a second report from the European-Mediterranean Seismological Centre (EMSC), which also listed the quake at magnitude 3.6.Weak shaking might have been felt in Black Eagle (pop. 900), located 3 miles from the epicenter; Great Falls (pop. 59,600), 4 miles away; Sun Prairie (pop. 1,600), 7 miles away; Malmstrom Air Force Base (pop. 3,500), 8 miles away; Vaughn (pop. 660), 10 miles away; and Ulm (pop. 740), 12 miles away. In Fort Benton (pop. 1,500, 36 miles away), Choteau (pop. 1,700, 44 miles away), and Conrad (pop. 2,600, 51 miles away), the quake was probably not felt.Earthquake data: Date & time: Sep 18, 2026 07:40 am (GMT -6) local time (18 Sep 2026 13:40 GMT)Magnitude: 3.6Hypocenter depth: 27.73 kmEpicenter coordinates: 47.56°N / 111.32°W (Cascade County, Montana, United States)Primary data source: USGS