Alaska earthquakes

M4.0 earthquake 29 km SSW of Adak, Alaska

A magnitude 4.0 earthquake struck 29 km SSW of Adak, Alaska on Thu, Dec 16, 2021, 9:48 AM HAST (19:48 UTC), 71 km (44 mi) below the surface.

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The earthquake

Magnitude: 4.0 (mb), light
Local time: Thu, Dec 16, 2021, 9:48 AM HAST
UTC: 2021-12-16 19:48:27 UTC
Depth: 70.5 km (43.8 mi), intermediate-depth
Epicenter: 51.633° N, 176.828° 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 6.6 km horizontally, 8.0 km in depth
Magnitude uncertainty: ±0.21
Depth from: From location
Station coverage gap: 208°, poorly surrounded by stations
Stations used: 37

Nearby

Within 100 km, magnitude 1.5 and up: 189 in the 60 days after this one and 10 in the 30 days before it.

After

The first 60 of 189.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000gf3l (also filed as ak021g35p1tz). Read Thu, Sep 24, 2026, 5:40 AM UTC.