Alaska earthquakes

M3.9 earthquake 84 km N of Adak, Alaska

A magnitude 3.9 earthquake struck 84 km N of Adak, Alaska on Mon, Jul 31, 2017, 3:38 PM HADT (00:38 UTC), 191 km (119 mi) below the surface.

A larger quake followed: M5.2 27 km ESE of Adak, Alaska. This one was a foreshock.

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The earthquake

Magnitude: 3.9 (mb, body-wave), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Mon, Jul 31, 2017, 3:38 PM HADT
UTC: 2017-08-01 00:38:48 UTC
Depth: 191.5 km (119.0 mi), intermediate-depth
Epicenter: 52.631° N, 176.656° 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 · ±0.101 · 26 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 13.1 km horizontally, 15.7 km in depth
Magnitude uncertainty: ±0.10
Depth from: From location
Station coverage gap: 117°
Stations used: 63

Nearby

Within 100 km, magnitude 1.5 and up: 24 in the 60 days after this one and 4 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 us2000a5j7 (also filed as ak0179s9p63a, ak16392574). Read Fri, Oct 2, 2026, 10:30 AM UTC.