M3.7 earthquake 66 km ENE of Atka, Alaska

A magnitude 3.7 earthquake struck 66 km ENE of Atka, Alaska on Wed, Mar 21, 2018, 6:02 AM HADT (15:02 UTC), 137 km (85 mi) below the surface.

A larger quake followed: M4.5 51 km NNE of Atka, 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	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.101 · 25 stations
3.2	ML, local (Richter)	Alaska Earthquake Center	Preliminary

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 24 in the 60 days after this one and 27 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event us1000d74r (also filed as ak0183ojxprm). Read Thu, Oct 1, 2026, 9:30 PM UTC.