Alaska earthquakes

M3.9 earthquake 197 km SE of Chignik, Alaska

A magnitude 3.9 earthquake struck 197 km SE of Chignik, Alaska on Wed, Sep 15, 2021, 2:48 AM AKDT (10:48 UTC), 33 km (21 mi) below the surface.

A larger quake followed: M5.6 181 km SE of Chignik, 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: 3.9 (ml), minor
Local time: Wed, Sep 15, 2021, 2:48 AM AKDT
UTC: 2021-09-15 10:48:57 UTC
Depth: 33.2 km (20.6 mi), shallow
Epicenter: 54.980° N, 156.304° 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: -3.9 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.

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Strike-slip
Moment magnitude: 4.3 Mwr
Nodal plane 1: Strike 122°, dip 56°, rake 10°
Nodal plane 2: Strike 26°, dip 82°, rake 145°

How well it is located

Reviewed by a seismologist.

Stations used: 134

Nearest places

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

Sand Point, AlaskaPopulation 1,064. Forecast269 kmE

Nearby

Within 100 km, magnitude 1.5 and up: 46 in the 60 days after this one and 106 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 ak021buuwa10 (also filed as us7000fbdz). Read Wed, Sep 23, 2026, 2:36 AM UTC.