Alaska earthquakes

M5.3 earthquake 216 km WSW of Adak, Alaska

A magnitude 5.3 earthquake struck 216 km WSW of Adak, Alaska on Fri, Feb 21, 2020, 12:20 AM HAST (10:20 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M5.7 239 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.

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The earthquake

Magnitude: 5.3 (mww), moderate
Local time: Fri, Feb 21, 2020, 12:20 AM HAST
UTC: 2020-02-21 10:20:14 UTC
Depth: 10.0 km (6.2 mi), shallow
Epicenter: 50.835° N, 179.267° W
Region: Alaska
Tsunami flag: Yes: a large quake in an oceanic region
Status: Reviewed by a seismologist

Tsunami

The USGS flags a quake this large in an oceanic region. The flag does not mean a tsunami happened; the tsunami warning centers decide that, and their messages are below when they issued any.

Current tsunami warnings: tsunami.gov. Warnings in force in the US also appear on our alerts pages.

Did you feel it?

No one has reported feeling this quake to the USGS.

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Oblique reverse
Moment magnitude: 5.3 Mww
Nodal plane 1: Strike 291°, dip 26°, rake 139°
Nodal plane 2: Strike 58°, dip 73°, rake 69°

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 2.1 km horizontally, 1.7 km in depth
Magnitude uncertainty: ±0.04
Depth from: Operator assigned
Station coverage gap: 76°
Stations used: 147

Nearby

Within 100 km, magnitude 2.3 and up: 54 in the 60 days after this one and 133 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 us70007u2w (also filed as at00q61rdp, ak0202e60pcj, iscgem617539261). Read Wed, Sep 30, 2026, 7:00 AM UTC.