Alaska earthquakes

M3.9 earthquake 49 km WSW of Adak, Alaska

A magnitude 3.9 earthquake struck 49 km WSW of Adak, Alaska on Mon, Dec 5, 2016, 9:40 AM HAST (19:40 UTC), 89 km (55 mi) below the surface.

A larger quake followed: M4.9 107 km WSW 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, Dec 5, 2016, 9:40 AM HAST
UTC: 2016-12-05 19:40:07 UTC
Depth: 88.9 km (55.2 mi), intermediate-depth
Epicenter: 51.773° N, 177.336° 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 · ±0.121 · 18 stations
3.5	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 15.7 km horizontally, 6.1 km in depth
Magnitude uncertainty: ±0.12
Stations used: 21

Nearby

Within 100 km, magnitude 1.5 and up: at least 199 in the 60 days after this one and 56 in the 30 days before it.

After

The first 60 of at least 199.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us20007zld (also filed as ak14608455, ak016fmm9tnd). Read Sat, Oct 3, 2026, 2:01 PM UTC.