Montana earthquakes

M2.5 earthquake 20 km SSW of Mammoth, Wyoming

A magnitude 2.5 earthquake struck 20 km SSW of Mammoth, Wyoming on Fri, Mar 1, 1985, 4:33 PM MST (23:33 UTC), 11 km (7 mi) below the surface.

A larger quake followed: M2.8 20 km SSW of Mammoth, Wyoming. This one was a foreshock.

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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
2.5 (md), micro
Local time
UTC
1985-03-01 23:33:27 UTC
Depth
11.3 km (7.0 mi), shallow
Epicenter
44.797° N, 110.772° W
Region
Montana
Tsunami flag
No
Status
Reviewed by a seismologist

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Location uncertainty
About 0.5 km horizontally, 0.7 km in depth
Depth from
From location
Station coverage gap
108°
Stations used
21

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 13 in the 60 days after this one and 1 in the 30 days before it.

After

  1. 2.820 km SSW of Mammoth, Wyoming · 15180 days ago · 12 km deep · 0 km away
  2. 1.520 km SSW of Mammoth, Wyoming · 15180 days ago · 5 km deep · 1 km away
  3. 2.420 km SSW of Mammoth, Wyoming · 15180 days ago · 12 km deep · 2 km away
  4. 1.921 km SSW of Mammoth, Wyoming · 15180 days ago · 11 km deep · 1 km away
  5. 1.620 km SSW of Mammoth, Wyoming · 15180 days ago · 6 km deep · 1 km away
  6. 1.620 km SSW of Mammoth, Wyoming · 15179 days ago · 5 km deep · 1 km away
  7. 3.623 km SSW of Mammoth, Wyoming · 15176 days ago · 5 km deep · 3 km away
  8. 3.223 km S of Mammoth, Wyoming · 15176 days ago · 5 km deep · 8 km away
  9. 2.319 km SSW of Mammoth, Wyoming · 15171 days ago · 28 km deep · 1 km away
  10. 3.529 km W of Hebgen Lake Estates, Montana · 15162 days ago · 5 km deep · 62 km away
  11. 2.041 km SSE of Mammoth, Wyoming · 15138 days ago · 2 km deep · 31 km away
  12. 1.821 km SSW of Mammoth, Wyoming · 15125 days ago · 12 km deep · 3 km away
  13. 1.9Idaho-Montana border region · 15121 days ago · 12 km deep · 43 km away

Before

  1. 1.835 km E of West Yellowstone, Montana · 15184 days ago · 3 km deep · 23 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event uu50019495 (also filed as usp0002cb7). Read Tue, Sep 22, 2026, 8:55 PM UTC.