The November 4, 1949 earthquake

M5.1near Primo Tapia, B.C., MX, California

A magnitude 5.1 earthquake 3.7 miles deep, 38.9 miles off San Diego County. The 415th strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 5.7 on November 4, 1949.

The earthquake

Magnitude: 5.1; local magnitude (ml)
Depth: 3.7 mi; 6.0 km below the surface
Local time: Friday, November 4, 1949; 20:35 PST; 04:35 UTC on Nov 5, 1949
Epicentre: 31.98°N, 116.99°W; 38.9 mi from San Diego County
In California’s record: 415th; strongest of 97,065 since 1900
Within 50 miles: 1; county; more on this date

USGS ANSS Comprehensive Earthquake Catalog, event ci3355580 (“27km SSW of Primo Tapia, B.C., MX”). 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

San Diego CountyCA · 38.9 mi

Cities, largest first

Chula VistaCA · 44.6 mi
National CityCA · 47.6 mi
Imperial BeachCA · 40.9 mi
CoronadoCA · 47.6 mi

Earthquakes around the epicentre

305 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

November 4, 1949M5.7
June 24, 1939M5.2

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