Alaska earthquakes

M4.0 earthquake 106 km NNW of Nikolski, Alaska

A magnitude 4.0 earthquake struck 106 km NNW of Nikolski, Alaska on Fri, Jul 20, 2018, 10:12 AM AKDT (18:12 UTC), 225 km (140 mi) below the surface.

A larger quake followed: M4.7 46 km W of Nikolski, Alaska. This one was a foreshock.

Dutch Harbor forecast More in Alaska

Map

Where this earthquake was located, with the others nearby. Select one for its page.

Open the live map with earthquakes

The earthquake

Magnitude: 4.0 (mb, body-wave), light
Magnitude from: USGS National Earthquake Information Center
Local time: Fri, Jul 20, 2018, 10:12 AM AKDT
UTC: 2018-07-20 18:12:49 UTC
Depth: 224.6 km (139.6 mi), intermediate-depth
Epicenter: 53.760° N, 169.689° 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
4.0	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.088 · 35 stations
4.0	mb, body-wave	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 9.7 km horizontally, 8.5 km in depth
Magnitude uncertainty: ±0.09
Depth from: From location
Station coverage gap: 115°
Stations used: 121

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Dutch Harbor, AlaskaPopulation 4,376. Forecast207 kmW

Nearby

Within 100 km, magnitude 1.5 and up: 9 in the 60 days after this one and 2 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 us2000g9yv (also filed as ak01898pt8n6, ak19921345). Read Sat, Oct 3, 2026, 10:45 AM UTC.