Alaska earthquakes

M4.0 earthquake 233 km SSE of Perryville, Alaska

A magnitude 4.0 earthquake struck 233 km SSE of Perryville, Alaska on Thu, Jul 29, 2021, 11:56 PM AKDT (07:56 UTC), 24 km (15 mi) below the surface.

A larger quake followed: M4.1 204 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: 4.0 (mb), light
Local time: Thu, Jul 29, 2021, 11:56 PM AKDT
UTC: 2021-07-30 07:56:00 UTC
Depth: 24.0 km (14.9 mi), shallow
Epicenter: 54.044° N, 157.479° 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: -5.8 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.

Location uncertainty: About 4.9 km horizontally, 6.1 km in depth
Magnitude uncertainty: ±0.18
Depth from: From location
Station coverage gap: 162°
Stations used: 136

Nearest places

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

Sand Point, AlaskaPopulation 1,064. Forecast242 kmSE

Nearby

Within 100 km, magnitude 1.5 and up: 75 in the 60 days after this one and 21 in the 30 days before it.

After

The first 60 of 75.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000f0r0 (also filed as ak0219p2w62g). Read Thu, Sep 24, 2026, 3:03 AM UTC.