Alaska earthquakes

M3.3 earthquake 30 km SW of Adak, Alaska

A magnitude 3.3 earthquake struck 30 km SW of Adak, Alaska on Mon, Sep 21, 2020, 4:34 PM HADT (01:34 UTC), 87 km (54 mi) below the surface.

A larger quake followed: M4.3 68 km SSE of Adak, 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: 3.3 (ml), minor
Local time: Mon, Sep 21, 2020, 4:34 PM HADT
UTC: 2020-09-22 01:34:50 UTC
Depth: 86.5 km (53.8 mi), intermediate-depth
Epicenter: 51.710° N, 176.985° 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 7.8 km horizontally, 4.4 km in depth
Magnitude uncertainty: ±0.12
Depth from: From location
Station coverage gap: 190°, poorly surrounded by stations
Stations used: 32

Nearby

Within 100 km, magnitude 1.5 and up: 144 in the 60 days after this one and 96 in the 30 days before it.

After

The first 60 of 144.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000c6bw (also filed as ak020c7xr57g). Read Sun, Sep 27, 2026, 11:07 PM UTC.