Alaska earthquakes

M4.0 earthquake 163 km SE of Atka, Alaska

A magnitude 4.0 earthquake struck 163 km SE of Atka, Alaska on Tue, Apr 20, 2021, 4:32 PM HADT (01:32 UTC), 26 km (16 mi) below the surface.

A larger quake followed: M4.2 95 km SE of Atka, Alaska. This one was a foreshock.

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

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The earthquake

Magnitude
4.0 (mb), light
Local time
UTC
2021-04-21 01:32:41 UTC
Depth
25.8 km (16.0 mi), shallow
Epicenter
51.178° N, 172.496° W
Region
Alaska
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 3.0 km horizontally, 6.4 km in depth
Magnitude uncertainty
±0.10
Depth from
From location
Station coverage gap
206°, poorly surrounded by stations
Stations used
57

Nearby

Within 100 km, magnitude 1.5 and up: 22 in the 60 days after this one and 7 in the 30 days before it.

After

  1. 3.168 km SE of Atka, Alaska · 1980 days ago · 35 km deep · 96 km away
  2. 2.5191 km SSE of Atka, Alaska · 1979 days ago · 10 km deep · 53 km away
  3. 1.978 km SE of Atka, Alaska · 1978 days ago · 12 km deep · 84 km away
  4. 2.194 km SE of Atka, Alaska · 1974 days ago · 18 km deep · 70 km away
  5. 3.7126 km SSE of Atka, Alaska · 1972 days ago · 38 km deep · 65 km away
  6. 2.684 km SSE of Atka, Alaska · 1959 days ago · 35 km deep · 85 km away
  7. 3.0177 km SSE of Atka, Alaska · 1959 days ago · 22 km deep · 65 km away
  8. 2.1140 km SSE of Atka, Alaska · 1955 days ago · 38 km deep · 71 km away
  9. 4.295 km SE of Atka, Alaska · 1951 days ago · 16 km deep · 69 km away
  10. 4.281 km SE of Atka, Alaska · 1951 days ago · 41 km deep · 81 km away
  11. 5.175 km SE of Atka, Alaska · 1951 days ago · 21 km deep · 88 km away
  12. 3.879 km SE of Atka, Alaska · 1951 days ago · 45 km deep · 84 km away
  13. 3.6123 km SSE of Atka, Alaska · 1951 days ago · 39 km deep · 53 km away
  14. 4.198 km SE of Atka, Alaska · 1951 days ago · 45 km deep · 67 km away
  15. 4.099 km SE of Atka, Alaska · 1951 days ago · 35 km deep · 65 km away
  16. 2.4118 km SSE of Atka, Alaska · 1942 days ago · 37 km deep · 95 km away
  17. 3.3107 km SSE of Atka, Alaska · 1939 days ago · 33 km deep · 64 km away
  18. 2.0141 km SE of Atka, Alaska · 1938 days ago · 24 km deep · 21 km away
  19. 2.5159 km SSE of Atka, Alaska · 1935 days ago · 10 km deep · 43 km away
  20. 2.9Andreanof Islands, Aleutian Islands, Alaska · 1931 days ago · 35 km deep · 64 km away
  21. 4.189 km SSE of Atka, Alaska · 1930 days ago · 30 km deep · 80 km away
  22. 2.6217 km ESE of Atka, Alaska · 1923 days ago · 10 km deep · 72 km away

Before

  1. 3.1153 km E of Atka, Alaska · 1984 days ago · 20 km deep · 94 km away
  2. 1.978 km SSE of Atka, Alaska · 1986 days ago · 17 km deep · 93 km away
  3. 2.7139 km SE of Atka, Alaska · 1993 days ago · 10 km deep · 26 km away
  4. 2.2Andreanof Islands, Aleutian Islands, Alaska · 1995 days ago · 15 km deep · 95 km away
  5. 4.276 km ESE of Atka, Alaska · 1996 days ago · 189 km deep · 92 km away
  6. 2.7100 km SSE of Atka, Alaska · 2011 days ago · 35 km deep · 99 km away
  7. 2.9177 km SE of Atka, Alaska · 2012 days ago · 25 km deep · 17 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000e3fh (also filed as ak02153lfxv2). Read Thu, Sep 24, 2026, 4:59 AM UTC.