Alaska earthquakes

M4.2 earthquake 227 km SW of Adak, Alaska

A magnitude 4.2 earthquake struck 227 km SW of Adak, Alaska on Thu, Feb 18, 2021, 11:08 PM HAST (09:08 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M5.6 209 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.

Open the live map with earthquakes

The earthquake

Magnitude: 4.2 (mb), light
Local time: Thu, Feb 18, 2021, 11:08 PM HAST
UTC: 2021-02-19 09:08:40 UTC
Depth: 10.0 km (6.2 mi), shallow
Epicenter: 50.755° N, 179.358° W
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.

Location uncertainty: About 5.7 km horizontally, 1.9 km in depth
Magnitude uncertainty: ±0.07
Depth from: Operator assigned
Station coverage gap: 215°, poorly surrounded by stations
Stations used: 99

Nearby

Within 100 km, magnitude 1.5 and up: 60 in the 60 days after this one and 24 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 us6000diwr (also filed as ak0212aua2gg). Read Fri, Sep 25, 2026, 9:46 PM UTC.