M2.5 earthquake 253 km W of Adak, Alaska

A magnitude 2.5 earthquake struck 253 km W of Adak, Alaska on Sun, Oct 4, 2020, 8:27 PM GMT+12 (08:27 UTC), 110 km (68 mi) below the surface.

A larger quake followed: M4.3 Andreanof Islands, Aleutian Islands, 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 · ±0.162 · 6 stations
2.3	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: 63 in the 60 days after this one and 85 in the 30 days before it.

The first 60 of 63.

From the USGS Earthquake Hazards Program and its partner networks, event us6000c7x7 (also filed as ak020crwbr85). Read Thu, Oct 1, 2026, 3:41 PM UTC.