Alaska earthquakes

M3.9 earthquake 71 km NE of Adak, Alaska

A magnitude 3.9 earthquake struck 71 km NE of Adak, Alaska on Mon, Aug 17, 2020, 11:19 PM HADT (08:19 UTC), 154 km (96 mi) below the surface.

A larger quake followed: M5.3 76 km SW of Atka, Alaska. This one was a foreshock.

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The earthquake

Magnitude
3.9 (mb), minor
Local time
UTC
2020-08-18 08:19:06 UTC
Depth
153.8 km (95.6 mi), intermediate-depth
Epicenter
52.296° N, 175.846° 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 11.0 km horizontally, 5.5 km in depth
Magnitude uncertainty
±0.21
Depth from
From location
Station coverage gap
94°
Stations used
45

Nearby

Within 100 km, magnitude 1.5 and up: 105 in the 60 days after this one and 52 in the 30 days before it.

After

The first 60 of 105.

Before

Earthquakes todayAlaska earthquakesLive radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us7000bclu (also filed as ak020am60q4c). Read Tue, Sep 29, 2026, 3:59 PM UTC.