The November 20, 1915 earthquake

M6.6Baja California-Sonora Border Region, Mexico, Arizona

A magnitude 6.6 earthquake 6.2 miles deep, 39.6 miles off Yuma County. The 2nd strongest in Arizona’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900.

The earthquake

Magnitude: 6.6; moment magnitude (mw)
Depth: 6.2 mi; 10.0 km below the surface
Local time: Saturday, November 20, 1915; 17:13 MST; 00:13 UTC on Nov 21, 1915
Epicentre: 31.93°N, 114.95°W; 39.6 mi from Yuma County
In Arizona’s record: 2nd; strongest of 6,972 since 1900
Within 50 miles: 1; county; more on this date

USGS ANSS Comprehensive Earthquake Catalog, event iscgem913953 (“Baja California-Sonora Border Region, Mexico”). 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

Yuma CountyAZ · 39.6 mi

Cities, largest first

YumaAZ · 47.3 mi
San LuisAZ · 40.4 mi
SomertonAZ · 48.5 mi

Earthquakes around the epicentre

2,163 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.

No earlier earthquake of magnitude 5 or more within 50 miles in the catalogue since 1900.

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