Idaho earthquakes

M1.6 earthquake 10 km SSW of Mackay, Idaho

A magnitude 1.6 earthquake struck 10 km SSW of Mackay, Idaho on Mon, Aug 20, 2018, 11:36 PM MDT (05:36 UTC), 3 km (2 mi) below the surface.

A larger quake followed: M2.8 13 km SE of Challis, Idaho. 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
1.6 (ML, local (Richter)), micro
Magnitude from
Montana Bureau of Mines and Geology
Local time
UTC
2018-08-21 05:36:29 UTC
Depth
3.4 km (2.1 mi), shallow
Epicenter
43.822° N, 113.656° W
Region
Idaho
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 0.9 km horizontally, 4.6 km in depth
Magnitude uncertainty
±0.13
Depth from
From location
Station coverage gap
191°, poorly surrounded by stations
Stations used
6

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 9 in the 60 days after this one and 4 in the 30 days before it.

After

  1. 2.110 km W of Clayton, Idaho · 2967 days ago · 13 km deep · 85 km away
  2. 1.813 km NNE of Clayton, Idaho · 2961 days ago · 3 km deep · 84 km away
  3. 1.935 km ESE of Clayton, Idaho · 2956 days ago · 0 km deep · 46 km away
  4. 2.813 km SE of Challis, Idaho · 2941 days ago · 5 km deep · 76 km away · felt by 3
  5. 2.336 km ENE of Challis, Idaho · 2939 days ago · 11 km deep · 94 km away
  6. 2.434 km NE of Challis, Idaho · 2939 days ago · 11 km deep · 97 km away
  7. 1.634 km SE of Stanley, Idaho · 2935 days ago · 14 km deep · 84 km away
  8. 1.610 km SE of Challis, Idaho · 2930 days ago · 7 km deep · 79 km away
  9. 1.616 km SE of Challis, Idaho · 2921 days ago · 4 km deep · 73 km away

Before

  1. 2.426 km NE of Challis, Idaho · 2971 days ago · 5 km deep · 94 km away
  2. 1.727 km S of Clayton, Idaho · 2974 days ago · 4 km deep · 66 km away
  3. 2.212 km W of Clayton, Idaho · 2979 days ago · 12 km deep · 87 km away
  4. 2.121 km NNW of Clayton, Idaho · 2996 days ago · 12 km deep · 97 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event mb80307494. Read Mon, Oct 5, 2026, 4:07 AM UTC.