Alaska earthquakes

M4.0 earthquake 269 km WSW of Adak, Alaska

A magnitude 4.0 earthquake struck 269 km WSW of Adak, Alaska on Mon, Jul 18, 2016, 8:31 AM GMT+12 (20:31 UTC), 74 km (46 mi) below the surface.

A larger quake followed: M5.6 269 km W of Adak, Alaska. This one was a foreshock.

Map

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The earthquake

Magnitude: 4.0 (mb, body-wave), light
Magnitude from: USGS National Earthquake Information Center
Local time: Mon, Jul 18, 2016, 8:31 AM GMT+12
UTC: 2016-07-17 20:31:46 UTC
Depth: 74.1 km (46.0 mi), intermediate-depth
Epicenter: 51.203° N, 179.631° E
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 · ±0.09 · 33 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 7.5 km horizontally, 4.8 km in depth
Magnitude uncertainty: ±0.09
Depth from: From location
Station coverage gap: 213°, poorly surrounded by stations
Stations used: 57

Nearby

Within 100 km, magnitude 1.5 and up: 123 in the 60 days after this one and 69 in the 30 days before it.

After

The first 60 of 123.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us20006gpn (also filed as ak13763020, ak01695g1h72). Read Sun, Oct 4, 2026, 7:09 AM UTC.