M1.8 earthquake 131 km WSW of Adak, Alaska

A magnitude 1.8 earthquake struck 131 km WSW of Adak, Alaska on Tue, May 4, 2021, 3:42 AM HADT (12:42 UTC), 13 km (8 mi) below the surface.

A larger quake followed: M4.2 122 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
1.8	ML, local (Richter)	Alaska Earthquake Center	Preferred · Preliminary
1.87	ML, local (Richter)	AV	Final · ±0.208889481605023 · 8 stations

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 72 in the 60 days after this one and 59 in the 30 days before it.

The first 60 of 72.

From the USGS Earthquake Hazards Program and its partner networks, event ak0215pa1c0t (also filed as av91234421). Read Thu, Oct 1, 2026, 4:04 AM UTC.