M3.3 earthquake 153 km WSW of Adak, Alaska

A magnitude 3.3 earthquake struck 153 km WSW of Adak, Alaska on Sat, Dec 20, 2025, 6:18 AM HAST (16:18 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M4.6 137 km SW 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
3.3	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.085 · 18 stations
3.5	ML, local (Richter)	Alaska Earthquake Center	Reviewed · ±0.2 · 25 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: 73 in the 60 days after this one and 45 in the 30 days before it.

The first 60 of 73.

From the USGS Earthquake Hazards Program and its partner networks, event us6000s9pb (also filed as ak2025yzftwh). Read Fri, Oct 2, 2026, 2:11 AM UTC.