The September 4, 1955 earthquake
M5.8near Boulder Creek, California
A magnitude 5.8 earthquake 9.3 miles deep, centred in Santa Cruz County. The 107th strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 6.3 on October 22, 1926.
The earthquake
- Magnitude
- 5.8
- moment magnitude (mw)
- Depth
- 9.3 mi
- 15.0 km below the surface
- Local time
- Sunday, September 4, 1955
- 19:01 PDT; 02:01 UTC on Sep 5, 1955
- In California’s record
- 107th
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event iscgem889890 (“7 km NNW of Boulder Creek, California”). 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
- Santa Cruz CountyCA · inside
- San Mateo CountyCA · 1.9 mi
- Santa Clara CountyCA · 3.8 mi
- Alameda CountyCA · 19.8 mi
- Monterey CountyCA · 28.8 mi
- San Benito CountyCA · 34.3 mi
- Contra Costa CountyCA · 38.0 mi
- Stanislaus CountyCA · 38.3 mi
- San Francisco CountyCA · 38.5 mi
- San Joaquin CountyCA · 40.5 mi
- Marin CountyCA · 48.0 mi
Earthquakes around the epicentre
1,823 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
- April 18, 1906M7.9
- July 1, 1911M6.5
- October 22, 1926M6.3
- October 22, 1926M6.3
- August 2, 1903M6.2
- June 11, 1903M6.1
- March 10, 1910M5.8
- December 31, 1910M5.7
- November 8, 1914M5.5
- October 24, 1926M5.5
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.