Alaska earthquakes

M3.5 earthquake 75 km SW of Nikolski, Alaska

A magnitude 3.5 earthquake struck 75 km SW of Nikolski, Alaska on Tue, Nov 21, 2017, 9:09 PM AKST (06:09 UTC), 39 km (24 mi) below the surface.

A larger quake followed: M4.7 156 km SW of Nikolski, Alaska. This one was a foreshock.

Unalaska forecast More in Alaska

Map

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

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The earthquake

Magnitude: 3.5 (ML, local (Richter)), minor
Magnitude from: USGS National Earthquake Information Center
Local time: Tue, Nov 21, 2017, 9:09 PM AKST
UTC: 2017-11-22 06:09:56 UTC
Depth: 38.9 km (24.2 mi), shallow
Epicenter: 52.401° N, 169.552° 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
3.5	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.137 · 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 4.2 km horizontally, 24.0 km in depth
Magnitude uncertainty: ±0.14
Depth from: From location
Station coverage gap: 215°, poorly surrounded by stations
Stations used: 25

Nearest places

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

Unalaska, AlaskaPopulation 4,491. Forecast260 kmSW

Nearby

Within 100 km, magnitude 1.5 and up: 44 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 us2000bt55 (also filed as ak17371104, ak017ez8tsez). Read Fri, Oct 2, 2026, 3:19 AM UTC.