Alaska earthquakes

M4.1 earthquake 67 km S of Cantwell, Alaska

A magnitude 4.1 earthquake struck 67 km S of Cantwell, Alaska on Thu, Sep 21, 2017, 2:15 PM AKDT (22:15 UTC), 20 km (13 mi) below the surface.

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Map

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

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The earthquake

Magnitude: 4.1 (Mw, moment), light
Magnitude from: Alaska Earthquake Center
Local time: Thu, Sep 21, 2017, 2:15 PM AKDT
UTC: 2017-09-21 22:15:20 UTC
Depth: 20.3 km (12.6 mi), shallow
Epicenter: 62.783° N, 148.876° W
Region: Alaska
Felt reports: 3
Strongest shaking: IV, light 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
4.1	Mw, moment	Alaska Earthquake Center	Preferred · Preliminary
4.1	Mwr, regional moment	USGS National Earthquake Information Center	Reviewed · ±0.027 · 132 stations

Shaking

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

Strongest estimated: IV, light shaking
Map: Automatic

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

Did you feel it?

3 people reported to the USGS what they felt; the strongest reported shaking was II, weak shaking.

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%

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Oblique reverse
Moment magnitude: 4.1 Mwr
Nodal plane 1: Strike 62°, dip 42°, rake 129°
Nodal plane 2: Strike 195°, dip 59°, rake 60°

How well it is located

Reviewed by a seismologist.

Stations used: 197

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 165 in the 60 days after this one and 70 in the 30 days before it.

After

The first 60 of 165.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak017c4z2f1d (also filed as ak16875653, us2000asvu). Read Sat, Oct 3, 2026, 9:26 AM UTC.