Alaska earthquakes

M4.0 earthquake 52 km E of Nikolski, Alaska

A magnitude 4.0 earthquake struck 52 km E of Nikolski, Alaska on Mon, Jul 12, 2021, 6:11 PM AKDT (02:11 UTC), 45 km (28 mi) below the surface.

A larger quake followed: M4.6 70 km E 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: Mon, Jul 12, 2021, 6:11 PM AKDT
UTC: 2021-07-13 02:11:47 UTC
Depth: 44.6 km (27.7 mi), shallow
Epicenter: 52.887° N, 168.079° W
Region: Alaska
Felt reports: 1
Strongest shaking: II, 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: II, weak shaking
Peak ground acceleration: 0.2% of gravity
Peak ground velocity: -1.8 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

1 person reported to the USGS what they felt; the strongest reported shaking was I, not felt shaking.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 5.0 km horizontally, 6.6 km in depth
Magnitude uncertainty: ±0.07
Depth from: From location
Station coverage gap: 126°
Stations used: 60

Nearest places

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

Unalaska, AlaskaPopulation 4,491. Forecast150 kmSW

Nearby

Within 100 km, magnitude 1.5 and up: 94 in the 60 days after this one and 30 in the 30 days before it.

After

The first 60 of 94.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000ele4 (also filed as ak0218wvinin). Read Sun, Sep 27, 2026, 9:45 AM UTC.