Alaska earthquakes

M4.0 earthquake 40 km ESE of Nikolski, Alaska

A magnitude 4.0 earthquake struck 40 km ESE of Nikolski, Alaska on Thu, Oct 22, 2020, 7:16 PM AKDT (03:16 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M6.4 46 km ESE of Nikolski, Alaska. This one was a foreshock.

Unalaska 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, Oct 22, 2020, 7:16 PM AKDT
UTC: 2020-10-23 03:16:03 UTC
Depth: 35.0 km (21.7 mi), shallow
Epicenter: 52.758° N, 168.348° W
Region: Alaska
Tsunami flag: No
Status: Reviewed by a seismologist

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 3.8 km horizontally, 2.0 km in depth
Magnitude uncertainty: ±0.13
Depth from: Operator assigned
Station coverage gap: 141°
Stations used: 49

Nearest places

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

Unalaska, AlaskaPopulation 4,491. Forecast173 kmSW

Nearby

Within 100 km, magnitude 1.5 and up: 167 in the 60 days after this one and 21 in the 30 days before it.

After

The first 60 of 167.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000cbv4 (also filed as ak020dn8htbp). Read Wed, Sep 30, 2026, 4:13 AM UTC.