Alaska earthquakes

M7.1 earthquake 60 km SW of Adak, Alaska

A magnitude 7.1 earthquake struck 60 km SW of Adak, Alaska on Tue, Mar 12, 1957, 12:45 AM GMT-11 (11:45 UTC), 20 km (12 mi) below the surface.

A larger quake followed: M7.1 75 km S of Adak, Alaska. This one was a foreshock.

Map

Where this earthquake was located, with the others nearby. Select one for its page.

Open the live map with earthquakes

The earthquake

Magnitude: 7.1 (Mw, moment), major
Magnitude from: ISC-GEM global catalog
Local time: Tue, Mar 12, 1957, 12:45 AM GMT-11
UTC: 1957-03-12 11:45:00 UTC
Depth: 20.0 km (12.4 mi), shallow
Epicenter: 51.481° N, 177.243° W
Region: Alaska
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

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
7.11	Mw, moment	ISC-GEM global catalog	Preferred · Final · ±0.2
7.0	Ms, surface-wave	USGS historic United States catalog	Final

What happened

The USGS’s account of the effects of this earthquake.

Maximum observed Modified Mercalli Intensity (MMI) I

Felt on Adak and Umnak Islands.

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.

From the USGS event page for iscgem886120. U.S. Geological Survey text and figures are in the public domain.

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Magnitude uncertainty: ±0.20
Depth from: From location

Nearby

Within 100 km, magnitude 4.1 and up: 4 in the 60 days after this one and 5 in the 30 days before it.

After

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event iscgem886120 (also filed as ushis2163). Read Thu, Oct 1, 2026, 4:26 PM UTC.