Alaska earthquakes

M4.3 earthquake 72 km SSW of Nanwalek, Alaska

A magnitude 4.3 earthquake struck 72 km SSW of Nanwalek, Alaska on Thu, Mar 4, 2021, 1:48 AM AKST (10:48 UTC), 55 km (34 mi) below the surface.

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Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude: 4.3 (ml), light
Local time: Thu, Mar 4, 2021, 1:48 AM AKST
UTC: 2021-03-04 10:48:11 UTC
Depth: 54.7 km (34.0 mi), shallow
Epicenter: 58.782° N, 152.524° W
Region: Alaska
Felt reports: 4
Strongest shaking: III, weak shaking
PAGER alert: Green
Tsunami flag: Yes: a large quake in an oceanic region
Status: Reviewed by a seismologist

Tsunami

The USGS flags a quake this large in an oceanic region. The flag does not mean a tsunami happened; the tsunami warning centers decide that, and their messages are below when they issued any.

Current tsunami warnings: tsunami.gov. Warnings in force in the US also appear on our alerts pages.

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: 277.0% of gravity
Peak ground velocity: 0.4 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.

Estimated impact

The USGS PAGER system estimates deaths and economic losses from the shaking and the population and buildings exposed to it.

Alert level: Green: little or no damage or loss of life expected

Deaths: estimated chance of each range
Range	Chance
Under 1	69%
1 to 10	29%
10 to 100	2%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Economic losses: estimated chance of each range
Range, million USD	Chance
Under 1	65%
1 to 10	30%
10 to 100	4%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

How well it is located

Reviewed by a seismologist.

Stations used: 274

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 173 in the 60 days after this one and 93 in the 30 days before it.

After

The first 60 of 173.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak0212wd3idi (also filed as us7000dfen, at00qpfy0b). Read Mon, Sep 28, 2026, 6:07 PM UTC.