M2.5 earthquake 111 km S of Adak, Alaska

A magnitude 2.5 earthquake struck 111 km S of Adak, Alaska on Fri, Jan 31, 2020, 3:20 PM HAST (01:20 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M4.1 90 km SSE 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
2.5	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed
2.5	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: 103 in the 60 days after this one and 54 in the 30 days before it.

The first 60 of 103.

From the USGS Earthquake Hazards Program and its partner networks, event us70007s51 (also filed as ak0201gxwvy4). Read Fri, Oct 2, 2026, 3:35 AM UTC.