M4.0 earthquake 47 km ESE of Adak, Alaska

A magnitude 4.0 earthquake struck 47 km ESE of Adak, Alaska on Tue, Feb 17, 2026, 1:17 PM HAST (23:17 UTC), 60 km (37 mi) below the surface.

A larger quake followed: M5.0 89 km SSW 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
4.0	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.1 · 27 stations
4.5	ML, local (Richter)	Alaska Earthquake Center	Reviewed · ±0.2 · 39 stations

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 110 in the 60 days after this one and 76 in the 30 days before it.

The first 60 of 110.

From the USGS Earthquake Hazards Program and its partner networks, event us6000s9w6 (also filed as ak2026dkblcf). Read Thu, Oct 1, 2026, 9:17 PM UTC.