Alaska earthquakes

M4.7 earthquake 81 km SSW of Unalaska, Alaska

A magnitude 4.7 earthquake struck 81 km SSW of Unalaska, Alaska on Sat, Jul 3, 2021, 5:42 AM AKDT (13:42 UTC), 47 km (29 mi) below the surface.

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: 4.7 (mwr), light
Local time: Sat, Jul 3, 2021, 5:42 AM AKDT
UTC: 2021-07-03 13:42:53 UTC
Depth: 46.6 km (29.0 mi), shallow
Epicenter: 53.170° N, 166.895° W
Region: Alaska
Felt reports: 3
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: 1.0% of gravity
Peak ground velocity: -0.5 cm/s
Map: Automatic

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

Did you feel it?

3 people reported to the USGS what they felt; the strongest reported shaking was III, weak shaking.

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Reverse (thrust)
Moment magnitude: 4.7 Mwr
Nodal plane 1: Strike 71°, dip 71°, rake 83°
Nodal plane 2: Strike 273°, dip 20°, rake 111°

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 4.0 km horizontally, 5.0 km in depth
Magnitude uncertainty: ±0.06
Depth from: From location
Station coverage gap: 86°
Stations used: 107

Nearest places

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

Unalaska, AlaskaPopulation 4,491. Forecast82 kmSSW

Nearby

Within 100 km, magnitude 1.7 and up: 66 in the 60 days after this one and 12 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 us7000eigv (also filed as ak0218givlw0). Read Wed, Sep 23, 2026, 8:33 PM UTC.