Alaska earthquakes

M4.0 earthquake 65 km S of Nikolski, Alaska

A magnitude 4.0 earthquake struck 65 km S of Nikolski, Alaska on Wed, Aug 9, 2017, 5:52 AM AKDT (13:52 UTC), 21 km (13 mi) below the surface.

A larger quake followed: M4.9 130 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: 4.0 (mb, body-wave), light
Magnitude from: USGS National Earthquake Information Center
Local time: Wed, Aug 9, 2017, 5:52 AM AKDT
UTC: 2017-08-09 13:52:38 UTC
Depth: 21.3 km (13.2 mi), shallow
Epicenter: 52.355° N, 168.965° W
Region: Alaska
Strongest shaking: II, weak shaking
PAGER alert: Green
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 · ±0.122 · 18 stations
4.0	mb, body-wave	Alaska Earthquake Center	Preliminary

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: II, weak shaking
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

No one has reported feeling this quake to the USGS.

Estimated impact

The USGS PAGER system estimates deaths and economic losses from the shaking and the population and buildings exposed to it.

Alert level: Green: little or no damage or loss of life expected

Deaths: estimated chance of each range
Range	Chance
Under 1	69%
1 to 10	29%
10 to 100	2%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Economic losses: estimated chance of each range
Range, million USD	Chance
Under 1	65%
1 to 10	30%
10 to 100	4%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 6.1 km horizontally, 6.8 km in depth
Magnitude uncertainty: ±0.12
Stations used: 42

Nearest places

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

Unalaska, AlaskaPopulation 4,491. Forecast234 kmSW

Nearby

Within 100 km, magnitude 1.5 and up: 92 in the 60 days after this one and 41 in the 30 days before it.

After

The first 60 of 92.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us2000a6ph (also filed as ak16489558, ak017a5ptk6j). Read Fri, Oct 2, 2026, 11:17 AM UTC.