Alaska earthquakes

M3.4 earthquake 132 km WSW of Adak, Alaska

A magnitude 3.4 earthquake struck 132 km WSW of Adak, Alaska on Mon, Dec 20, 2021, 4:32 AM HAST (14:32 UTC), 74 km (46 mi) below the surface.

A larger quake followed: M5.1 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: 3.4 (ml), minor
Local time: Mon, Dec 20, 2021, 4:32 AM HAST
UTC: 2021-12-20 14:32:17 UTC
Depth: 73.9 km (45.9 mi), intermediate-depth
Epicenter: 51.515° N, 178.460° 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 7.7 km horizontally, 8.3 km in depth
Magnitude uncertainty: ±0.09
Depth from: From location
Station coverage gap: 192°, poorly surrounded by stations
Stations used: 27

Nearby

Within 100 km, magnitude 1.5 and up: 153 in the 60 days after this one and 65 in the 30 days before it.

After

The first 60 of 153.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000gfzx (also filed as ak021g9ortl8). Read Mon, Sep 28, 2026, 5:32 AM UTC.