Alaska earthquakes

M3.9 earthquake 45 km S of Adak, Alaska

A magnitude 3.9 earthquake struck 45 km S of Adak, Alaska on Mon, Mar 29, 2021, 10:24 PM HADT (07:24 UTC), 47 km (29 mi) below the surface.

A larger quake followed: M4.4 44 km SE of Adak, 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: 3.9 (ml), minor
Local time: Mon, Mar 29, 2021, 10:24 PM HADT
UTC: 2021-03-30 07:24:52 UTC
Depth: 46.6 km (28.9 mi), shallow
Epicenter: 51.474° N, 176.514° 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 5.7 km horizontally, 13.7 km in depth
Magnitude uncertainty: ±0.13
Depth from: From location
Station coverage gap: 236°, poorly surrounded by stations
Stations used: 19

Nearby

Within 100 km, magnitude 1.5 and up: 130 in the 60 days after this one and 55 in the 30 days before it.

After

The first 60 of 130.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000dxmc (also filed as ak02143b56hu). Read Thu, Sep 24, 2026, 8:39 AM UTC.