Alaska earthquakes

M4.0 earthquake 51 km SSE of Adak, Alaska

A magnitude 4.0 earthquake struck 51 km SSE of Adak, Alaska on Wed, Sep 16, 2020, 5:57 AM HADT (14:57 UTC), 35 km (22 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: 4.0 (mb), light
Local time: Wed, Sep 16, 2020, 5:57 AM HADT
UTC: 2020-09-16 14:57:24 UTC
Depth: 35.0 km (21.7 mi), shallow
Epicenter: 51.448° N, 176.350° 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 5.1 km horizontally, 1.9 km in depth
Magnitude uncertainty: ±0.07
Depth from: Operator assigned
Station coverage gap: 173°
Stations used: 97

Nearby

Within 100 km, magnitude 1.5 and up: 127 in the 60 days after this one and 84 in the 30 days before it.

After

The first 60 of 127.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000bp6w (also filed as ak020by8ekht). Read Wed, Sep 30, 2026, 8:32 PM UTC.