Alaska earthquakes

M3.9 earthquake 86 km NE of Atka, Alaska

A magnitude 3.9 earthquake struck 86 km NE of Atka, Alaska on Sun, Oct 21, 2018, 6:08 AM HADT (15:08 UTC), 240 km (149 mi) below the surface.

A larger quake followed: M4.7 53 km N of Atka, 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: 3.9 (mb, body-wave), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Sun, Oct 21, 2018, 6:08 AM HADT
UTC: 2018-10-21 15:08:49 UTC
Depth: 240.0 km (149.1 mi), intermediate-depth
Epicenter: 52.710° N, 173.241° W
Region: Alaska
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
3.9	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.23 · 8 stations
3.1	ML, local (Richter)	Alaska Earthquake Center	Preliminary

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 9.3 km horizontally, 9.8 km in depth
Magnitude uncertainty: ±0.23
Depth from: From location
Station coverage gap: 143°
Stations used: 38

Nearby

Within 100 km, magnitude 1.5 and up: 22 in the 60 days after this one and 17 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 us1000hfdz (also filed as ak20288486, ak018digzcub). Read Thu, Oct 1, 2026, 12:15 PM UTC.