The April 15, 1940 earthquake

M7.0near Attu Station, Alaska

A magnitude 7.0 earthquake 18.6 miles deep, 5.3 miles off Aleutians West Census Area. The 50th strongest in Alaska’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900.

The earthquake

Magnitude: 7.0; moment magnitude (mw)
Depth: 18.6 mi; 30.0 km below the surface
Local time: Monday, April 15, 1940; 19:43 NST; 06:43 UTC on Apr 16, 1940
Epicentre: 52.85°N, 173.55°E; 5.3 mi from Aleutians West Census Area
In Alaska’s record: 50th; strongest of 124,625 since 1900
Within 50 miles: 1; county; more on this date

USGS ANSS Comprehensive Earthquake Catalog, event iscgem901283 (“24 km E of Attu Station, Alaska”). The USGS event page carries the ShakeMap, felt reports and the official summary.

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 · 5.3 mi

Earthquakes around the epicentre

233 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 15, 1940M7.0
February 22, 1935M6.8
October 18, 1912M6.7
July 22, 1923M6.5
May 30, 1931M6.0
May 30, 1931M5.8
December 17, 1929M5.7

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