Alaska earthquakes

M3.1 earthquake 121 km WSW of Adak, Alaska

A magnitude 3.1 earthquake struck 121 km WSW of Adak, Alaska on Thu, Sep 23, 2021, 3:00 PM HADT (00:00 UTC), 78 km (49 mi) below the surface.

A larger quake followed: M5.5 185 km WSW 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: 3.1 (ml), minor
Local time: Thu, Sep 23, 2021, 3:00 PM HADT
UTC: 2021-09-24 00:00:30 UTC
Depth: 78.5 km (48.8 mi), intermediate-depth
Epicenter: 51.637° N, 178.346° 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 8.0 km horizontally, 6.5 km in depth
Magnitude uncertainty: ±0.10
Depth from: From location
Station coverage gap: 175°
Stations used: 33

Nearby

Within 100 km, magnitude 1.5 and up: 145 in the 60 days after this one and 54 in the 30 days before it.

After

The first 60 of 145.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000fwh4 (also filed as ak021c9khq6h). Read Thu, Sep 24, 2026, 9:06 AM UTC.