M3.5 earthquake 55 km SW of Adak, Alaska

A magnitude 3.5 earthquake struck 55 km SW of Adak, Alaska on Sat, May 27, 2023, 12:05 AM HADT (09:05 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M5.3 135 km WSW 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
3.5	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.091 · 16 stations
3.1	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: at least 199 in the 60 days after this one and 149 in the 30 days before it.

The first 60 of at least 199.

From the USGS Earthquake Hazards Program and its partner networks, event us7000k5ip (also filed as ak0236r9e1hn). Read Thu, Oct 1, 2026, 9:42 PM UTC.