The August 20, 1959 earthquake

M5.0near Hebgen Lake Estates, Montana

A magnitude 5.0 earthquake 3.1 miles deep, centred in Beaverhead County. The 23rd strongest in Montana’s record since 1900, and the strongest within 50 miles since a magnitude 5.0 on August 19, 1959.

The earthquake

Magnitude: 5.0; as reported (uk)
Depth: 3.1 mi; 5.0 km below the surface
Local time: Thursday, August 20, 1959; 12:11 MST; 19:11 UTC
Epicentre: 44.70°N, 111.68°W; In Beaverhead County
In Montana’s record: 23rd; strongest of 1,459 since 1900
Within 50 miles: 8; counties; more on this date

USGS ANSS Comprehensive Earthquake Catalog, event ushis2405 (“39 km W of Hebgen Lake Estates, Montana”). 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

Beaverhead CountyMT · inside
Madison CountyMT · 5.1 mi
Fremont CountyID · 9.0 mi
Clark CountyID · 10.1 mi
Gallatin CountyMT · 15.1 mi
Teton CountyWY · 30.8 mi
Park CountyWY · 30.8 mi
Park CountyMT · 37.2 mi

Earthquakes around the epicentre

370 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

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