The August 6, 1973 earthquake
M5.1near Santa Cruz Is. (E end), CA
A magnitude 5.1 earthquake 10.5 miles deep, 4.3 miles off Ventura County. The 373rd strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 5.3 on February 21, 1973. 1 aftershock of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.1
- local magnitude (ml)
- Depth
- 10.5 mi
- 16.9 km below the surface
- Local time
- Monday, August 6, 1973
- 16:29 PDT; 23:29 UTC
- In California’s record
- 373rd
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event ci3319386 (“9km SSE of Santa Cruz Is. (E end), 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.
1
Aftershocks in 30 days
3.0
Largest aftershock, Aug 15, 1973
0
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.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- Ventura CountyCA · 4.3 mi
- Santa Barbara CountyCA · 5.6 mi
- Los Angeles CountyCA · 31.0 mi
Cities, largest first
- OxnardCA · 22.7 mi
- Simi ValleyCA · 46.7 mi
- Thousand OaksCA · 38.1 mi
- VenturaCA · 24.9 mi
- Santa BarbaraCA · 33.8 mi
- CamarilloCA · 31.3 mi
- MoorparkCA · 41.1 mi
- GoletaCA · 39.7 mi
- Santa PaulaCA · 36.1 mi
- CalabasasCA · 47.9 mi
- Port HuenemeCA · 21.0 mi
- Agoura HillsCA · 42.8 mi
Earthquakes around the epicentre
397 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 29, 1925M6.8
- February 18, 1926M5.5
- June 29, 1926M5.5
- June 30, 1941M5.5
- February 21, 1973M5.3
- August 30, 1930M5.2
- April 18, 1928M5.2
- July 4, 1968M5.0
- August 5, 1930M5.0
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.