Sixty years ago today, at 11:37PM, a 7.3 magnitude earthquake sent a wall of the mountain down into the Madison River creating Quake Lake and killing at least 28 people. The Madison River went dry and evacuation orders went out to the town of Ennis.

https://mtstandard.com/news/state-and-regional/retrospective-hebgen-lake-earthquake/collection_53f773bd-75ca-5128-8986-000a1acc742c.html#1