Alaska earthquakes

M5.4 earthquake 158 km SE of Chignik, Alaska

A magnitude 5.4 earthquake struck 158 km SE of Chignik, Alaska on Thu, Jul 29, 2021, 12:32 PM AKDT (20:32 UTC), 21 km (13 mi) below the surface.

A larger quake followed: M6.9 125 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.

Open the live map with earthquakes

The earthquake

Magnitude: 5.4 (mww), moderate
Local time: Thu, Jul 29, 2021, 12:32 PM AKDT
UTC: 2021-07-29 20:32:43 UTC
Depth: 20.8 km (12.9 mi), shallow
Epicenter: 55.215° N, 156.759° W
Region: Alaska
Felt reports: 1
Strongest shaking: III, weak shaking
PAGER alert: Green
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: III, weak shaking
Peak ground acceleration: 0.6% of gravity
Peak ground velocity: -0.8 cm/s
Map: Automatic

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

Did you feel it?

1 person reported to the USGS what they felt; the strongest reported shaking was I, not felt 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: Green: little or no damage or loss of life expected

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	65%
1 to 10	30%
10 to 100	4%
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%

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: 5.5 Mwb
Nodal plane 1: Strike 64°, dip 72°, rake 76°
Nodal plane 2: Strike 282°, dip 22°, rake 126°
Landslide alert: Green
Liquefaction alert: Green

How well it is located

Reviewed by a seismologist.

Stations used: 125

Nearest places

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

Sand Point, AlaskaPopulation 1,064. Forecast237 kmE

Nearby

Within 100 km, magnitude 2.4 and up: at least 201 in the 60 days after this one and 197 in the 30 days before it.

After

The first 60 of at least 201.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak0219nmyhv7 (also filed as us6000f0ca, iscgem622450981). Read Mon, Sep 28, 2026, 9:43 PM UTC.