Montana earthquakes

M5.9 earthquake 26 km SSE of Mammoth, Wyoming

A magnitude 5.9 earthquake struck 26 km SSE of Mammoth, Wyoming on Mon, Jun 30, 1975, 12:54 PM MDT (18:54 UTC), 7 km (4 mi) below the surface.

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Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude: 5.9 (ms), moderate
Local time: Mon, Jun 30, 1975, 12:54 PM MDT
UTC: 1975-06-30 18:54:13 UTC
Depth: 7.0 km (4.3 mi), shallow
Epicenter: 44.745° N, 110.605° W
Region: Montana
Strongest shaking: VIII, severe shaking
Tsunami flag: No
Status: Reviewed by a seismologist

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: VIII, severe shaking
Peak ground acceleration: 49.7% of gravity
Peak ground velocity: 3.6 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Stations used: 157

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 2.5 and up: 16 in the 60 days after this one and 2 in the 30 days before it.

After

Before

Earthquakes today Montana earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event usp0000buf (also filed as ushis3347, iscgem728427, atlas19750630185416). Read Tue, Sep 22, 2026, 10:21 AM UTC.