Alaska earthquakes

M5.5 earthquake 173 km WSW of Adak, Alaska

A magnitude 5.5 earthquake struck 173 km WSW of Adak, Alaska on Mon, Apr 16, 1973, 3:48 AM GMT-11 (14:48 UTC), 54 km (34 mi) below the surface.

A larger quake followed: M5.8 222 km WSW of Adak, Alaska. This one was a foreshock.

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The earthquake

Magnitude
5.5 (mb), moderate
Local time
UTC
1973-04-16 14:48:02 UTC
Depth
54.0 km (33.6 mi), shallow
Epicenter
51.123° N, 178.829° 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.

Stations used
121

Nearby

Within 100 km, magnitude 2.5 and up: 10 in the 60 days after this one and 4 in the 30 days before it.

After

  1. 4.8237 km WSW of Adak, Alaska · 19510 days ago · 54 km deep · 71 km away
  2. 4.0248 km WSW of Adak, Alaska · 19510 days ago · 45 km deep · 77 km away
  3. 4.1248 km WSW of Adak, Alaska · 19510 days ago · 42 km deep · 79 km away
  4. 3.7186 km SW of Adak, Alaska · 19504 days ago · 33 km deep · 36 km away
  5. 5.3207 km WSW of Adak, Alaska · 19493 days ago · 61 km deep · 55 km away
  6. 5.8222 km WSW of Adak, Alaska · 19477 days ago · 39 km deep · 69 km away
  7. 4.9221 km WSW of Adak, Alaska · 19477 days ago · 56 km deep · 62 km away
  8. 4.1239 km WSW of Adak, Alaska · 19474 days ago · 46 km deep · 75 km away
  9. 5.8201 km WSW of Adak, Alaska · 19457 days ago · 48 km deep · 44 km away
  10. 5.4204 km WSW of Adak, Alaska · 19457 days ago · 50 km deep · 45 km away

Before

  1. 3.8224 km W of Adak, Alaska · 19521 days ago · 111 km deep · 97 km away
  2. 5.0134 km WSW of Adak, Alaska · 19527 days ago · 50 km deep · 42 km away
  3. 4.2209 km WSW of Adak, Alaska · 19541 days ago · 51 km deep · 39 km away
  4. 4.9196 km WSW of Adak, Alaska · 19541 days ago · 40 km deep · 29 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event usp00001e4 (also filed as ushis3228, iscgem761620). Read Tue, Sep 22, 2026, 4:55 AM UTC.