Alaska earthquakes

M3.7 earthquake 33 km SSW of Unalaska, Alaska

A magnitude 3.7 earthquake struck 33 km SSW of Unalaska, Alaska on Thu, May 20, 2021, 5:05 PM AKDT (01:05 UTC), 77 km (48 mi) below the surface.

A larger quake followed: M3.8 81 km S of Unalaska, Alaska. This one was a foreshock.

Unalaska forecast More in Alaska

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude: 3.7 (mb), minor
Local time: Thu, May 20, 2021, 5:05 PM AKDT
UTC: 2021-05-21 01:05:51 UTC
Depth: 77.4 km (48.1 mi), intermediate-depth
Epicenter: 53.617° N, 166.796° 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, 4.0 km in depth
Magnitude uncertainty: ±0.17
Depth from: From location
Station coverage gap: 169°
Stations used: 39

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Unalaska, AlaskaPopulation 4,491. Forecast33 kmSSW

Nearby

Within 100 km, magnitude 1.5 and up: 52 in the 60 days after this one and 17 in the 30 days before it.

After

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000e4yb (also filed as ak0216h7ejtv). Read Wed, Sep 23, 2026, 6:47 PM UTC.