Alaska earthquakes

M8.2 earthquake 2021 Chignik, Alaska Earthquake

A magnitude 8.2 earthquake struck 2021 Chignik, Alaska Earthquake on Wed, Jul 28, 2021, 10:15 PM AKDT (06:15 UTC), 35 km (22 mi) below the surface.

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Map

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

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The earthquake

Magnitude: 8.2 (mww), great
Local time: Wed, Jul 28, 2021, 10:15 PM AKDT
UTC: 2021-07-29 06:15:49 UTC
Depth: 35.0 km (21.7 mi), shallow
Epicenter: 55.364° N, 157.888° W
Region: Alaska
Felt reports: 512
Strongest shaking: VII, very strong shaking
PAGER alert: Yellow
Tsunami flag: Yes: a large quake in an oceanic region
Status: Reviewed by a seismologist

Tsunami

The USGS flags a quake this large in an oceanic region. The flag does not mean a tsunami happened; the tsunami warning centers decide that, and their messages are below when they issued any.

Current tsunami warnings: tsunami.gov. Warnings in force in the US also appear on our alerts pages.

Shaking

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

Strongest estimated: VII, very strong shaking
Peak ground acceleration: 40.1% of gravity
Peak ground velocity: 3.3 cm/s
Map: Automatic

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

Did you feel it?

512 people reported to the USGS what they felt; the strongest reported shaking was IX, violent shaking.

Estimated impact

The USGS PAGER system estimates deaths and economic losses from the shaking and the population and buildings exposed to it.

Alert level: Yellow: some damage and deaths possible, a local or regional response

Deaths: estimated chance of each range
Range	Chance
Under 1	69%
1 to 10	29%
10 to 100	2%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Economic losses: estimated chance of each range
Range, million USD	Chance
Under 1	48%
1 to 10	33%
10 to 100	16%
100 to 1,000	3%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Fault motion and ground failure

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

Faulting: Reverse (thrust)
Moment magnitude: 8.2 Mww
Nodal plane 1: Strike 239°, dip 14°, rake 95°
Nodal plane 2: Strike 54°, dip 76°, rake 89°
Landslide alert: Yellow
Liquefaction alert: Orange

How well it is located

Reviewed by a seismologist.

Stations used: 202

Nearest places

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

Sand Point, AlaskaPopulation 1,064. Forecast165 kmE

Nearby

Within 100 km, magnitude 2.5 and up: 200 in the 60 days after this one and 0 in the 30 days before it.

After

The first 60 of 200.

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak0219neiszm (also filed as us6000f02w, ak0219nejcxv, at00qwzteb, pt21210001, usauto6000f02w, iscgem620857937). Read Tue, Sep 22, 2026, 12:14 PM UTC.