Alaska earthquakes

M3.9 earthquake 61 km WNW of Atka, Alaska

A magnitude 3.9 earthquake struck 61 km WNW of Atka, Alaska on Sun, Feb 21, 2016, 1:42 PM HAST (23:42 UTC), 146 km (91 mi) below the surface.

A larger quake followed: M4.6 Andreanof Islands, Aleutian Islands, Alaska. This one was a foreshock.

Map

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The earthquake

Magnitude: 3.9 (mb, body-wave), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Sun, Feb 21, 2016, 1:42 PM HAST
UTC: 2016-02-21 23:42:19 UTC
Depth: 145.9 km (90.7 mi), intermediate-depth
Epicenter: 52.423° N, 175.023° W
Region: Alaska
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 · ±0.209 · 6 stations
3.2	ML, local (Richter)	Alaska Earthquake Center	Preliminary

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 9.8 km horizontally, 10.2 km in depth
Magnitude uncertainty: ±0.21
Depth from: From location
Station coverage gap: 126°
Stations used: 43

Nearby

Within 100 km, magnitude 1.5 and up: 80 in the 60 days after this one and 46 in the 30 days before it.

After

The first 60 of 80.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us10004sdr (also filed as ak12863465, ak0162edw26i). Read Mon, Oct 5, 2026, 12:57 PM UTC.