Alaska earthquakes

M3.7 earthquake 150 km SSE of Chignik, Alaska

A magnitude 3.7 earthquake struck 150 km SSE of Chignik, Alaska on Fri, Aug 20, 2021, 7:53 PM AKDT (03:53 UTC), 7 km (5 mi) below the surface.

A larger quake followed: M4.5 64 km SE of Perryville, Alaska. This one was a foreshock.

Sand Point 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 (ml), minor
Local time: Fri, Aug 20, 2021, 7:53 PM AKDT
UTC: 2021-08-21 03:53:57 UTC
Depth: 7.4 km (4.6 mi), shallow
Epicenter: 55.136° N, 157.169° W
Region: Alaska
Strongest shaking: I, not felt shaking
Tsunami flag: No
Status: Reviewed by a seismologist

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: I, not felt shaking
Peak ground acceleration: 0.0% of gravity
Peak ground velocity: -5.1 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Stations used: 71

Nearest places

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

Sand Point, AlaskaPopulation 1,064. Forecast212 kmE

Nearby

Within 100 km, magnitude 1.5 and up: 140 in the 60 days after this one and 59 in the 30 days before it.

After

The first 60 of 140.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak021apebqkj (also filed as us6000f987). Read Tue, Sep 22, 2026, 5:14 PM UTC.