Alaska earthquakes

M3.4 earthquake 43 km E of Adak, Alaska

A magnitude 3.4 earthquake struck 43 km E of Adak, Alaska on Thu, Mar 1, 2018, 1:40 AM HAST (11:40 UTC), 135 km (84 mi) below the surface.

A larger quake followed: M4.6 48 km SW of Atka, 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: 3.4 (ML, local (Richter)), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Thu, Mar 1, 2018, 1:40 AM HAST
UTC: 2018-03-01 11:40:43 UTC
Depth: 135.2 km (84.0 mi), intermediate-depth
Epicenter: 51.863° N, 176.005° 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
3.4	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.148 · 6 stations
2.7	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 7.6 km horizontally, 5.7 km in depth
Magnitude uncertainty: ±0.15
Depth from: From location
Station coverage gap: 196°, poorly surrounded by stations
Stations used: 16

Nearby

Within 100 km, magnitude 1.5 and up: 93 in the 60 days after this one and 56 in the 30 days before it.

After

The first 60 of 93.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us1000d1zc (also filed as ak18572648, ak0182rf199j). Read Fri, Oct 2, 2026, 3:54 AM UTC.