The November 20, 1971 earthquake
M5.4near Ferndale, California
A magnitude 5.4 earthquake 9.3 miles deep, 3.1 miles off Humboldt County. The 229th strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 5.5 on February 26, 1971.
The earthquake
- Magnitude
- 5.4
- moment magnitude (mw)
- Depth
- 9.3 mi
- 15.0 km below the surface
- Local time
- Saturday, November 20, 1971
- 05:59 PST; 13:59 UTC
- In California’s record
- 229th
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event iscgem778683 (“27 km SSW of Ferndale, 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
- Humboldt CountyCA · 3.1 mi
- Mendocino CountyCA · 32.3 mi
Earthquakes around the epicentre
2,492 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
- January 22, 1923M7.1
- February 9, 1941M6.8
- October 3, 1941M6.5
- June 6, 1932M6.5
- December 21, 1954M6.4
- April 23, 1906M6.4
- October 7, 1951M6.0
- September 22, 1952M6.0
- October 28, 1909M6.0
- March 18, 1910M6.0
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.