Alaska earthquakes

M4.0 earthquake 257 km WSW of Adak, Alaska

A magnitude 4.0 earthquake struck 257 km WSW of Adak, Alaska on Wed, Sep 22, 2021, 6:48 AM GMT+12 (18:48 UTC), 106 km (66 mi) below the surface.

A larger quake followed: M6.1 187 km WSW 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: 4.0 (mb), light
Local time: Wed, Sep 22, 2021, 6:48 AM GMT+12
UTC: 2021-09-21 18:48:39 UTC
Depth: 106.2 km (66.0 mi), intermediate-depth
Epicenter: 51.466° N, 179.706° E
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 7.9 km horizontally, 5.7 km in depth
Magnitude uncertainty: ±0.08
Depth from: From location
Station coverage gap: 167°
Stations used: 94

Nearby

Within 100 km, magnitude 1.5 and up: 118 in the 60 days after this one and 66 in the 30 days before it.

After

The first 60 of 118.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000fe4u (also filed as ak021c4wvsrg). Read Thu, Sep 24, 2026, 12:17 PM UTC.