M1.7 earthquake 82 km W of Adak, Alaska

A magnitude 1.7 earthquake struck 82 km W of Adak, Alaska on Mon, Sep 13, 2021, 3:35 AM HADT (12:35 UTC), 12 km (7 mi) below the surface.

A larger quake followed: M3.9 116 km WSW 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
1.7	ML, local (Richter)	Alaska Earthquake Center	Preferred · Preliminary
1.79	ML, local (Richter)	AV	Final · ±0.302402811734045 · 23 stations

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 114 in the 60 days after this one and 91 in the 30 days before it.

The first 60 of 114.

From the USGS Earthquake Hazards Program and its partner networks, event ak021brkxliz (also filed as av91373271). Read Thu, Oct 1, 2026, 4:04 AM UTC.