M3.3 earthquake 186 km SSW of Akhiok, Alaska

A magnitude 3.3 earthquake struck 186 km SSW of Akhiok, Alaska on Wed, Aug 4, 2021, 3:06 AM AKDT (11:06 UTC), 47 km (29 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
3.3	ML, local (Richter)	Alaska Earthquake Center	Preferred · Preliminary
3.5	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.066 · 30 stations

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 126 in the 60 days after this one and at least 200 in the 30 days before it.

The first 60 of 126.

From the USGS Earthquake Hazards Program and its partner networks, event ak0219xeo407 (also filed as us6000f26i). Read Thu, Oct 1, 2026, 8:28 PM UTC.