Alaska earthquakes

M3.8 earthquake 84 km NE of Adak, Alaska

A magnitude 3.8 earthquake struck 84 km NE of Adak, Alaska on Sat, Oct 9, 2021, 2:07 PM HADT (23:07 UTC), 182 km (113 mi) below the surface.

A larger quake followed: M4.1 147 km NNE 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: 3.8 (mb), minor
Local time: Sat, Oct 9, 2021, 2:07 PM HADT
UTC: 2021-10-09 23:07:50 UTC
Depth: 182.5 km (113.4 mi), intermediate-depth
Epicenter: 52.404° N, 175.752° 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: -5.2 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 10.9 km horizontally, 7.7 km in depth
Magnitude uncertainty: ±0.11
Depth from: From location
Station coverage gap: 102°
Stations used: 56

Nearby

Within 100 km, magnitude 1.5 and up: 66 in the 60 days after this one and 20 in the 30 days before it.

After

The first 60 of 66.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000fuk6 (also filed as ak021cyrag4g). Read Thu, Sep 24, 2026, 7:04 AM UTC.