The September 12, 1966 earthquake
M5.9near Truckee, California
A magnitude 5.9 earthquake 6.2 miles deep, centred in Nevada County. The 90th strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 6.0 on December 29, 1948. 3 aftershocks of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.9
- moment magnitude (mw)
- Depth
- 6.2 mi
- 10.0 km below the surface
- Local time
- Monday, September 12, 1966
- 09:41 PDT; 16:41 UTC
- In California’s record
- 90th
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event iscgem843363 (“9 km NW of Truckee, 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.
3
Aftershocks in 30 days
4.8
Largest aftershock, Sep 12, 1966
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
- Nevada CountyCA · inside
- Sierra CountyCA · 13.6 mi
- Placer CountyCA · 14.6 mi
- Washoe CountyNV · 20.9 mi
- Carson CityNV · 20.9 mi
- Plumas CountyCA · 22.4 mi
- Lassen CountyCA · 22.4 mi
- El Dorado CountyCA · 23.5 mi
- Douglas CountyNV · 23.9 mi
- Storey CountyNV · 30.3 mi
- Lyon CountyNV · 30.9 mi
- Alpine CountyCA · 37.2 mi
- Yuba CountyCA · 40.7 mi
- Butte CountyCA · 45.6 mi
- Amador CountyCA · 48.3 mi
Cities, largest first
- RenoNV · 24.3 mi
- SparksNV · 31.6 mi
- Carson CityNV · 32.1 mi
- South Lake TahoeCA · 35.5 mi
- TruckeeCA · 4.7 mi
- Grass ValleyCA · 44.1 mi
Earthquakes around the epicentre
400 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 24, 1914M6.4
- February 18, 1914M6.0
- December 29, 1948M6.0
- June 22, 1909M5.9
- April 1, 1959M5.6
- December 14, 1950M5.6
- September 25, 1953M5.3
- March 30, 1943M5.3
- May 9, 1952M5.1
- December 17, 1942M5.1
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.