M3.8 earthquake 48 km S of Adak, Alaska

A magnitude 3.8 earthquake struck 48 km S of Adak, Alaska on Sun, Jul 20, 2025, 12:37 PM HADT (21:37 UTC), 40 km (25 mi) below the surface.

A larger quake followed: M4.8 54 km W 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
3.8	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.207 · 6 stations
3.7	ML, local (Richter)	Alaska Earthquake Center	Preliminary

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

1 person reported to the USGS what they felt; the strongest reported shaking was II, weak shaking.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 191 in the 60 days after this one and 146 in the 30 days before it.

The first 60 of 191.

From the USGS Earthquake Hazards Program and its partner networks, event us7000qe5e (also filed as ak02598rqvvs). Read Sat, Oct 3, 2026, 1:44 AM UTC.