M4.8 earthquake 85 km E of Adak, Alaska

A magnitude 4.8 earthquake struck 85 km E of Adak, Alaska on Wed, May 21, 1986, 1:12 PM HADT (22:12 UTC), 33 km (21 mi) below the surface.

A larger quake followed: M5.5 27 km E of Adak, Alaska. This one was a foreshock.

Map

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

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

Felt (II) on Adak.

From the USGS event page for usp0002u9g. U.S. Geological Survey text and figures are in the public domain.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.8 and up: 66 in the 60 days after this one and 194 in the 30 days before it.

The first 60 of 66.

From the USGS Earthquake Hazards Program and its partner networks, event usp0002u9g. Read Sun, Oct 4, 2026, 6:17 AM UTC.