Alaska earthquakes

M4.2 earthquake 55 km SSW of Unalaska, Alaska

A magnitude 4.2 earthquake struck 55 km SSW of Unalaska, Alaska on Sat, Jul 29, 2023, 12:06 AM AKDT (08:06 UTC), 4 km (3 mi) below the surface.

A larger quake followed: M4.5 93 km S of Unalaska, 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: 4.2 (mb), light
Local time: Sat, Jul 29, 2023, 12:06 AM AKDT
UTC: 2023-07-29 08:06:53 UTC
Depth: 4.3 km (2.7 mi), shallow
Epicenter: 53.434° N, 166.938° W
Region: Alaska
Felt reports: 4
Strongest shaking: IV, light 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: IV, light shaking
Peak ground acceleration: 5.6% of gravity
Peak ground velocity: 0.9 cm/s
Map: Automatic

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

Did you feel it?

4 people reported to the USGS what they felt; the strongest reported shaking was IV, light shaking.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 3.0 km horizontally, 5.8 km in depth
Magnitude uncertainty: ±0.09
Depth from: From location
Station coverage gap: 160°
Stations used: 93

Nearest places

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

Unalaska, AlaskaPopulation 4,491. Forecast56 kmSSW

Nearby

Within 100 km, magnitude 1.5 and up: 154 in the 60 days after this one and 76 in the 30 days before it.

After

The first 60 of 154.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us6000kwh7 (also filed as ak0239nfnr0d). Read Tue, Sep 29, 2026, 5:41 PM UTC.