Alaska earthquakes

M5.1 earthquake 270 km W of Adak, Alaska

A magnitude 5.1 earthquake struck 270 km W of Adak, Alaska on Thu, Oct 22, 1987, 5:47 AM GMT+12 (17:47 UTC), 95 km (59 mi) below the surface.

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The earthquake

Magnitude
5.1 (mw), moderate
Local time
UTC
1987-10-21 17:47:30 UTC
Depth
94.9 km (59.0 mi), intermediate-depth
Epicenter
51.937° N, 179.439° E
Region
Alaska
Tsunami flag
No
Status
Reviewed by a seismologist

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Depth from
CONSTRAINED_BY_DEPTH_PHASES

Nearby

Within 100 km, magnitude 2.1 and up: 1 in the 60 days after this one and 1 in the 30 days before it.

After

  1. 4.7225 km W of Adak, Alaska · 14187 days ago · 88 km deep · 58 km away

Before

  1. 4.5285 km W of Adak, Alaska · 14235 days ago · 33 km deep · 50 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event usp00039fk (also filed as gcmtb102187c, gcmt19871021174730, iscgem455886). Read Tue, Sep 22, 2026, 6:32 AM UTC.