The December 27, 1960 earthquake
M5.9near Crescent City, California
A magnitude 5.9 earthquake 12.4 miles deep, 49.3 miles off Del Norte County. The 90th strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 6.0 on June 5, 1960. 1 aftershock of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.9
- moment magnitude (mw)
- Depth
- 12.4 mi
- 20.0 km below the surface
- Local time
- Tuesday, December 27, 1960
- 02:35 PST; 10:35 UTC
- In California’s record
- 90th
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event iscgem881080 (“81 km WSW of Crescent City, California”). 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
4.7
Largest aftershock, Dec 27, 1960
1
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
- Del Norte CountyCA · 49.3 mi
Earthquakes around the epicentre
192 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
- July 14, 1918M6.5
- April 23, 1906M6.4
- June 4, 1925M6.0
- June 5, 1960M6.0
- September 9, 1931M5.8
- April 28, 1923M5.6
- August 20, 1927M5.3
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.