Alaska earthquakes

M4.0 earthquake 161 km SW of Adak, Alaska

A magnitude 4.0 earthquake struck 161 km SW of Adak, Alaska on Tue, Nov 21, 2017, 11:06 AM HAST (21:06 UTC), 19 km (12 mi) below the surface.

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The earthquake

Magnitude: 4.0 (mb, body-wave), light
Magnitude from: USGS National Earthquake Information Center
Local time: Tue, Nov 21, 2017, 11:06 AM HAST
UTC: 2017-11-21 21:06:58 UTC
Depth: 18.7 km (11.6 mi), shallow
Epicenter: 51.005° N, 178.492° 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
4.0	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.149 · 12 stations
4.1	mb, body-wave	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 4.6 km horizontally, 11.3 km in depth
Magnitude uncertainty: ±0.15
Depth from: From location
Station coverage gap: 222°, poorly surrounded by stations
Stations used: 35

Nearby

Within 100 km, magnitude 1.5 and up: 181 in the 60 days after this one and 132 in the 30 days before it.

After

The first 60 of 181.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us2000bv1b (also filed as ak17366146, ak017exu7b14). Read Fri, Oct 2, 2026, 11:13 AM UTC.