M3.7 earthquake 176 km SSW of Akhiok, Alaska

A magnitude 3.7 earthquake struck 176 km SSW of Akhiok, Alaska on Thu, Jul 29, 2021, 10:46 PM AKDT (06:46 UTC), 35 km (21 mi) below the surface.

A larger quake followed: M5.6 181 km SE of Chignik, 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
3.7	ML, local (Richter)	Alaska Earthquake Center	Preferred · Preliminary
4.0	mb, body-wave	USGS National Earthquake Information Center	Reviewed · ±0.164 · 10 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.

Distance and direction from each place to the epicenter, with its forecast.

Within 100 km, magnitude 1.5 and up: at least 201 in the 60 days after this one and 135 in the 30 days before it.

The first 60 of at least 201.

From the USGS Earthquake Hazards Program and its partner networks, event ak0219p28psw (also filed as us6000f0j5). Read Mon, Oct 5, 2026, 7:25 AM UTC.