M 4.5 earthquake near Montana, USA — 1977-08-27

Magnitude 4.5 earthquake near 71 km S of Helena (USA), depth 10 km, 23:23 Local (1977-08-27 05:23 UTC). Shaking felt by ~414K people. Readings from every reporting agency, affected towns, aftershock sequence.

71 km S of Helena (USA) — 45.999, -111.69

EarthquakeLive.org