The November 21, 1952 earthquake
M6.2near Cambria, CA
A magnitude 6.2 earthquake 3.7 miles deep, 4.6 miles off San Luis Obispo County. The 48th strongest in California’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900. 6 aftershocks of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 6.2
- local magnitude (ml)
- Depth
- 3.7 mi
- 6.0 km below the surface
- Local time
- Friday, November 21, 1952
- 23:46 PST; 07:46 UTC on Nov 22, 1952
- In California’s record
- 48th
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event ci3307216 (“28km NW of Cambria, CA”). 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.
6
Aftershocks in 30 days
4.2
Largest aftershock, Nov 22, 1952
2
On the first day
0
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.
- Before the modern seismic networks of the 1970s many small aftershocks went unrecorded, so early sequences read short.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- San Luis Obispo CountyCA · 4.6 mi
- Monterey CountyCA · 5.1 mi
- San Benito CountyCA · 40.7 mi
- Fresno CountyCA · 46.4 mi
Cities, largest first
- San Luis ObispoCA · 48.7 mi
- Paso RoblesCA · 38.6 mi
- AtascaderoCA · 39.5 mi
- SoledadCA · 49.2 mi
- GreenfieldCA · 41.8 mi
- King CityCA · 35.8 mi
- Morro BayCA · 35.7 mi
Earthquakes around the epicentre
873 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
- June 7, 1934M5.8
- December 6, 1906M5.7
- December 28, 1939M5.2
- June 7, 1934M5.1
- February 26, 1932M5.0
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.