M3.3 earthquake 128 km SE of Adak, Alaska

A magnitude 3.3 earthquake struck 128 km SE of Adak, Alaska on Thu, Dec 21, 2023, 11:48 AM HAST (21:48 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
3.3	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.128 · 15 stations
2.9	ML, local (Richter)	Alaska Earthquake Center	Preliminary

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

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

The first 60 of 100.

From the USGS Earthquake Hazards Program and its partner networks, event us6000m2gu (also filed as ak023gbgklt0). Read Thu, Oct 1, 2026, 9:35 AM UTC.