The September 17, 2026 earthquake

M6.5near Nikolski, Alaska

A magnitude 6.5 earthquake 60.9 miles deep, 22.9 miles off Aleutians West Census Area. The 187th strongest in Alaska’s record since 1900, and the strongest within 50 miles since a magnitude 6.8 on February 21, 1957. 7 aftershocks of magnitude 2.5 or more followed within 30 days.

The earthquake

Magnitude: 6.5; moment magnitude (mww)
Depth: 60.9 mi; 98.0 km below the surface
Local time: Thursday, September 17, 2026; 05:19 HDT; 14:19 UTC
Epicentre: 52.88°N, 171.40°W; 22.9 mi from Aleutians West Census Area
In Alaska’s record: 187th; strongest of 124,625 since 1900
Within 50 miles: 1; county; more on this date

USGS ANSS Comprehensive Earthquake Catalog, event us7000ti1p (“170 km W of Nikolski, Alaska”). The USGS event page carries the ShakeMap, felt reports and the official summary.

Aftershocks

Earthquakes of magnitude 2.5 or more within 20 miles of the epicentre in the 30 days after.

Aftershocks in 30 days

4.1

Largest aftershock, Sep 17, 2026

On the first day

In the 7 days before

The search radius is the surface rupture length expected for an earthquake of this magnitude (Wells and Coppersmith, 1994), at least 20 and at most 600 miles, so a great earthquake's sequence is counted along its whole fault.

Counties and cities within 50 miles

Distance from the epicentre to each county boundary (zero when inside) and to each city centre.

Counties

Aleutians West Census AreaAK · 22.9 mi

Earthquakes around the epicentre

522 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.

Earlier earthquakes of magnitude 5 or more within 50 miles, strongest first

April 17, 1916M7.4
February 21, 1957M6.8
December 5, 1930M6.5
January 14, 1968M6.2
January 3, 1968M6.1
April 4, 1971M6.1
March 24, 1957M6.0
August 18, 1925M6.0
March 17, 1957M6.0
May 9, 1962M6.0

USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.