Alaska earthquakes

M3.9 earthquake 136 km S of Adak, Alaska

A magnitude 3.9 earthquake struck 136 km S of Adak, Alaska on Thu, Jan 18, 2018, 5:33 AM HAST (15:33 UTC), 28 km (17 mi) below the surface.

A larger quake followed: M4.3 177 km SSW 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: Thu, Jan 18, 2018, 5:33 AM HAST
UTC: 2018-01-18 15:33:05 UTC
Depth: 27.7 km (17.2 mi), shallow
Epicenter: 50.659° N, 176.339° 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 · ±0.052 · 95 stations
3.3	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 4.5 km horizontally, 8.3 km in depth
Magnitude uncertainty: ±0.05
Depth from: From location
Station coverage gap: 224°, poorly surrounded by stations
Stations used: 140

Nearby

Within 100 km, magnitude 1.5 and up: 53 in the 60 days after this one and 37 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 us2000cnap (also filed as ak18097922, ak018u0su3c). Read Fri, Oct 2, 2026, 7:07 AM UTC.