M 5.1 Earthquake in the USA (Helena) — August 20, 1999

M 5.1 Earthquake in the USA (Helena) — August 20, 1999. Epicenter 209 km S of Helena, depth 16 km, 07:50 Local (1999-08-20 13:50 UTC). Shaking felt by ~681K people. Readings from every reporting agency, affected towns, aftershock sequence.

209 km S of Helena (USA) — 44.785, -112.788

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