M3.3 earthquake 100 km NE of Adak, Alaska

A magnitude 3.3 earthquake struck 100 km NE of Adak, Alaska on Mon, Oct 23, 2023, 5:51 AM HADT (14:51 UTC), 205 km (127 mi) below the surface.

A larger quake followed: M4.3 84 km WSW 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 · ±0.081 · 20 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: 53 in the 60 days after this one and 35 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event us7000laaf (also filed as ak023dlrptb9). Read Thu, Oct 1, 2026, 2:39 AM UTC.