Alaska earthquakes

M2.8 earthquake 191 km S of Atka, Alaska

A magnitude 2.8 earthquake struck 191 km S of Atka, Alaska on Mon, Sep 21, 2020, 1:34 PM HADT (22:34 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M4.1 180 km SSE of Atka, Alaska. This one was a foreshock.

Map

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The earthquake

Magnitude: 2.8 (ML, local (Richter)), micro
Magnitude from: USGS National Earthquake Information Center
Local time: Mon, Sep 21, 2020, 1:34 PM HADT
UTC: 2020-09-21 22:34:57 UTC
Depth: 10.0 km (6.2 mi), shallow
Epicenter: 50.485° N, 174.453° 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
2.8	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.128 · 8 stations
2.6	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 8.3 km horizontally, 2.0 km in depth
Magnitude uncertainty: ±0.13
Depth from: Operator assigned
Station coverage gap: 294°, poorly surrounded by stations
Stations used: 18

Nearby

Within 100 km, magnitude 1.5 and up: 17 in the 60 days after this one and 6 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 us6000c3rz (also filed as ak020c6mpx31). Read Fri, Oct 2, 2026, 10:41 PM UTC.