Alaska earthquakes

M3.7 earthquake 55 km NE of Adak, Alaska

A magnitude 3.7 earthquake struck 55 km NE of Adak, Alaska on Wed, Apr 20, 2016, 3:26 PM HADT (00:26 UTC), 179 km (111 mi) below the surface.

A larger quake followed: M5.1 39 km SW of Adak, Alaska. This one was a foreshock.

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The earthquake

Magnitude: 3.7 (mb, body-wave), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Wed, Apr 20, 2016, 3:26 PM HADT
UTC: 2016-04-21 00:26:20 UTC
Depth: 179.0 km (111.2 mi), intermediate-depth
Epicenter: 52.245° N, 176.089° 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
3.7	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.206 · 6 stations
2.8	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 13.0 km horizontally, 6.3 km in depth
Magnitude uncertainty: ±0.21
Stations used: 22

Nearby

Within 100 km, magnitude 1.5 and up: 94 in the 60 days after this one and 50 in the 30 days before it.

After

The first 60 of 94.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us10005c04 (also filed as ak13488742, ak016558chjc). Read Sun, Oct 4, 2026, 8:50 AM UTC.