Alaska earthquakes

M3.7 earthquake 75 km SW of Adak, Alaska

A magnitude 3.7 earthquake struck 75 km SW of Adak, Alaska on Sun, Oct 31, 2021, 4:51 AM HADT (13:51 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M3.8 Andreanof Islands, Aleutian Islands, Alaska. This one was a foreshock.

Map

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

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The earthquake

Magnitude: 3.7 (mb), minor
Local time: Sun, Oct 31, 2021, 4:51 AM HADT
UTC: 2021-10-31 13:51:16 UTC
Depth: 35.2 km (21.9 mi), shallow
Epicenter: 51.358° N, 177.353° 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 4.3 km horizontally, 10.8 km in depth
Magnitude uncertainty: ±0.14
Depth from: From location
Station coverage gap: 197°, poorly surrounded by stations
Stations used: 54

Nearby

Within 100 km, magnitude 1.5 and up: 169 in the 60 days after this one and 30 in the 30 days before it.

After

The first 60 of 169.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000fus3 (also filed as ak021dyzf3v0). Read Thu, Sep 24, 2026, 8:38 AM UTC.