Alaska earthquakes

M3.9 earthquake 48 km E of Atka, Alaska

A magnitude 3.9 earthquake struck 48 km E of Atka, Alaska on Fri, Aug 13, 2021, 8:32 AM HADT (17:32 UTC), 105 km (65 mi) below the surface.

A larger quake followed: M4.7 67 km ESE of Atka, 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: 3.9 (mb), minor
Local time: Fri, Aug 13, 2021, 8:32 AM HADT
UTC: 2021-08-13 17:32:15 UTC
Depth: 105.0 km (65.2 mi), intermediate-depth
Epicenter: 52.154° N, 173.494° W
Region: Alaska
Strongest shaking: III, weak 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: III, weak shaking
Peak ground acceleration: 0.3% of gravity
Peak ground velocity: -2.5 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 8.6 km horizontally, 5.2 km in depth
Magnitude uncertainty: ±0.09
Depth from: From location
Station coverage gap: 155°
Stations used: 104

Nearby

Within 100 km, magnitude 1.5 and up: 70 in the 60 days after this one and 58 in the 30 days before it.

After

The first 60 of 70.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000f5rq (also filed as ak021ace7qoj). Read Thu, Sep 24, 2026, 3:07 AM UTC.