Intermountain Seismic Belt Historical Earthquake Project
September 23, 1945 – Flathead Lake, MT – M 5.5
At 2:57 a.m. on Sunday, September 23, 1945, a magnitude 5.5 earthquake occurred near Lakeside, Montana on the northwest side of Flathead Lake.
The earthquake was reported felt in western Montana, northern Idaho and eastern Washington. There were reports of dishes and windows rattling from Helena, Montana to Walla Walla, Washington. In Kalispell, Montana the shaking awakened most people. Many reported their homes creaking. No significant damage or injuries were reported.
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