Alaska earthquakes

M2.5 earthquake 227 km W of Adak, Alaska

A magnitude 2.5 earthquake struck 227 km W of Adak, Alaska on Mon, Nov 20, 2017, 11:23 PM HAST (09:23 UTC), 156 km (97 mi) below the surface.

A larger quake followed: M4.2 209 km W of Adak, Alaska. This one was a foreshock.

Map

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The earthquake

Magnitude: 2.5 (ML, local (Richter)), micro
Magnitude from: USGS National Earthquake Information Center
Local time: Mon, Nov 20, 2017, 11:23 PM HAST
UTC: 2017-11-21 09:23:02 UTC
Depth: 155.6 km (96.7 mi), intermediate-depth
Epicenter: 51.804° N, 179.937° 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
2.5	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed
2.5	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 7.0 km horizontally, 6.3 km in depth
Depth from: From location
Station coverage gap: 159°
Stations used: 12

Nearby

Within 100 km, magnitude 1.5 and up: 75 in the 60 days after this one and 47 in the 30 days before it.

After

The first 60 of 75.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us2000bv0v (also filed as ak017exn5mhs, ak17393867). Read Fri, Oct 2, 2026, 11:13 AM UTC.