Alaska earthquakes

M3.8 earthquake 158 km SSE of Chignik, Alaska

A magnitude 3.8 earthquake struck 158 km SSE of Chignik, Alaska on Thu, Jul 29, 2021, 9:40 PM AKDT (05:40 UTC), 35 km (22 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: 3.8 (ml), minor
Local time: Thu, Jul 29, 2021, 9:40 PM AKDT
UTC: 2021-07-30 05:40:55 UTC
Depth: 34.9 km (21.7 mi), shallow
Epicenter: 55.077° N, 157.086° 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: -4.6 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: Normal
Moment magnitude: 4.0 Mwr
Nodal plane 1: Strike 27°, dip 18°, rake -90°
Nodal plane 2: Strike 207°, dip 72°, rake -90°

How well it is located

Reviewed by a seismologist.

Stations used: 104

Nearest places

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

Sand Point, AlaskaPopulation 1,064. Forecast219 kmE

Nearby

Within 100 km, magnitude 1.5 and up: at least 202 in the 60 days after this one and at least 200 in the 30 days before it.

After

The first 60 of at least 202.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak0219p1m2xa (also filed as us6000f0is). Read Sat, Sep 26, 2026, 3:11 AM UTC.