Alaska earthquakes

M4.7 earthquake 142 km S of Akhiok, Alaska

A magnitude 4.7 earthquake struck 142 km S of Akhiok, Alaska on Fri, Jul 30, 2021, 2:11 PM AKDT (22:11 UTC), 12 km (7 mi) below the surface.

Womens Bay 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 (ML, local (Richter)), light
Magnitude from: Alaska Earthquake Center
Local time: Fri, Jul 30, 2021, 2:11 PM AKDT
UTC: 2021-07-30 22:11:41 UTC
Depth: 12.0 km (7.5 mi), shallow
Epicenter: 55.672° N, 154.443° W
Region: Alaska
Strongest shaking: III, weak shaking
PAGER alert: Green
Tsunami flag: Yes: a large quake in an oceanic region
Status: Reviewed by a seismologist

Magnitude estimates

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
4.7	ML, local (Richter)	Alaska Earthquake Center	Preferred · Preliminary
4.8	Mww, W-phase moment	USGS National Earthquake Information Center	Reviewed · ±0.056 · 31 stations
4.8	mb, body-wave	NOAA National Tsunami Warning Center	Reviewed · 12 stations
5.15	Mw, moment	ISC-GEM global catalog	Final · ±0.1

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: 0.3% 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?

No one has reported feeling this quake to the USGS.

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%

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: 4.8 Mww
Nodal plane 1: Strike 220°, dip 12°, rake 78°
Nodal plane 2: Strike 52°, dip 78°, rake 93°

How well it is located

Reviewed by a seismologist.

Stations used: 141

Nearest places

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

Womens Bay, AlaskaPopulation 719. Forecast248 kmSSW

Nearby

Within 100 km, magnitude 1.7 and up: 53 in the 60 days after this one and 33 in the 30 days before it.

After

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak0219pbk71d (also filed as at00qx2wbg, us6000f0u3, iscgem620923870). Read Thu, Oct 1, 2026, 9:21 AM UTC.