Alaska earthquakes

M3.9 earthquake 213 km WSW of Adak, Alaska

A magnitude 3.9 earthquake struck 213 km WSW of Adak, Alaska on Sun, Feb 20, 2022, 12:09 PM HAST (22:09 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M4.1 134 km SW of Adak, Alaska. This one was a foreshock.

Map

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

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The earthquake

Magnitude: 3.9 (mb, body-wave), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Sun, Feb 20, 2022, 12:09 PM HAST
UTC: 2022-02-20 22:09:04 UTC
Depth: 35.0 km (21.7 mi), shallow
Epicenter: 51.178° N, 179.502° W
Region: Alaska
Strongest shaking: III, weak shaking
Tsunami flag: No
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
3.9	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.096 · 29 stations
3.5	ML, local (Richter)	Alaska Earthquake Center	Preliminary

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: 0.8% of gravity
Peak ground velocity: -1.7 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.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 1.7 km horizontally, 2.0 km in depth
Magnitude uncertainty: ±0.10
Depth from: Operator assigned
Station coverage gap: 203°, poorly surrounded by stations
Stations used: 70

Nearby

Within 100 km, magnitude 1.5 and up: 176 in the 60 days after this one and 60 in the 30 days before it.

After

The first 60 of 176.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000gmjb (also filed as ak0222cpk63s). Read Mon, Oct 5, 2026, 11:38 AM UTC.