Alaska earthquakes

M4.0 earthquake 69 km SSE of Atka, Alaska

A magnitude 4.0 earthquake struck 69 km SSE of Atka, Alaska on Thu, Oct 28, 2021, 9:38 AM HADT (18:38 UTC), 53 km (33 mi) below the surface.

A larger quake followed: M4.3 107 km SSW of Atka, 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: Thu, Oct 28, 2021, 9:38 AM HADT
UTC: 2021-10-28 18:38:10 UTC
Depth: 52.7 km (32.8 mi), shallow
Epicenter: 51.600° N, 173.910° 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 6.1 km horizontally, 6.3 km in depth
Magnitude uncertainty: ±0.08
Depth from: From location
Station coverage gap: 142°
Stations used: 104

Nearby

Within 100 km, magnitude 1.5 and up: 68 in the 60 days after this one and 16 in the 30 days before it.

After

The first 60 of 68.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000fr5j (also filed as ak021du3pfnv). Read Thu, Sep 24, 2026, 3:24 PM UTC.