Alaska earthquakes

M4.0 earthquake 97 km S of Adak, Alaska

A magnitude 4.0 earthquake struck 97 km S of Adak, Alaska on Tue, Oct 20, 2020, 11:33 PM HADT (08:33 UTC), 27 km (17 mi) below the surface.

A larger quake followed: M5.0 124 km SW of Adak, Alaska. This one was a foreshock.

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The earthquake

Magnitude: 4.0 (mb), light
Local time: Tue, Oct 20, 2020, 11:33 PM HADT
UTC: 2020-10-21 08:33:28 UTC
Depth: 27.1 km (16.8 mi), shallow
Epicenter: 51.011° N, 176.870° 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 4.4 km horizontally, 6.9 km in depth
Magnitude uncertainty: ±0.14
Depth from: From location
Station coverage gap: 153°
Stations used: 40

Nearby

Within 100 km, magnitude 1.5 and up: 120 in the 60 days after this one and 74 in the 30 days before it.

After

The first 60 of 120.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000c6ar (also filed as ak020dk0hzhk). Read Mon, Sep 28, 2026, 5:36 AM UTC.