Alaska earthquakes

M4.3 earthquake 116 km NW of Atka, Alaska

A magnitude 4.3 earthquake struck 116 km NW of Atka, Alaska on Mon, Aug 30, 2021, 5:17 PM HADT (02:17 UTC), 255 km (158 mi) below the surface.

A larger quake followed: M4.7 49 km NE of Adak, Alaska. This one was a foreshock.

Map

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

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The earthquake

Magnitude: 4.3 (mb), light
Local time: Mon, Aug 30, 2021, 5:17 PM HADT
UTC: 2021-08-31 02:17:11 UTC
Depth: 254.5 km (158.2 mi), intermediate-depth
Epicenter: 52.857° N, 175.531° 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: 0.1% 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?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 6.4 km horizontally, 4.4 km in depth
Magnitude uncertainty: ±0.03
Depth from: From location
Station coverage gap: 72°
Stations used: 112

Nearby

Within 100 km, magnitude 1.5 and up: 25 in the 60 days after this one and 12 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 us7000f605 (also filed as ak021b5wvve7). Read Thu, Sep 24, 2026, 5:01 AM UTC.