M3.8 earthquake 106 km SE of Adak, Alaska

A magnitude 3.8 earthquake struck 106 km SE of Adak, Alaska on Thu, Dec 21, 2023, 7:43 PM HAST (05:43 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M4.9 124 km SSW of Atka, Alaska. This one was a foreshock.

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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
3.8	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.093 · 30 stations
3.7	ML, local (Richter)	Alaska Earthquake Center	Preliminary

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 111 in the 60 days after this one and 72 in the 30 days before it.

The first 60 of 111.

From the USGS Earthquake Hazards Program and its partner networks, event us7000lkvx (also filed as ak023gcuk254). Read Thu, Oct 1, 2026, 2:36 AM UTC.