M3.9 earthquake 41 km SSW of Adak, Alaska

A magnitude 3.9 earthquake struck 41 km SSW of Adak, Alaska on Sat, Dec 9, 2023, 8:06 AM HAST (18:06 UTC), 46 km (28 mi) below the surface.

A larger quake followed: M4.5 125 km SW of Adak, 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
3.9	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.091 · 16 stations
3.4	ML, local (Richter)	Alaska Earthquake Center	Preliminary

The USGS’s account of the effects of this earthquake.

From the USGS event page for us7000lkid. U.S. Geological Survey text and figures are in the public domain.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 139 in the 60 days after this one and 94 in the 30 days before it.

The first 60 of 139.

From the USGS Earthquake Hazards Program and its partner networks, event us7000lkid (also filed as ak023frk3920). Read Sun, Oct 4, 2026, 9:04 PM UTC.