1966 September 12 16:41 UTC
Minor but extensive fractures in the ground were observed in the area northeast of Truckee, extending 16 km on a trend N. 30degrees E. from Prosser Reservior to Hoke Valley. Chimmneys toppled and masonry walls were cracked at Boca, Hirschdale (near Boca Dam), Hobart Mills (near Prosser Dam), Loyalton, and Sierraville. Pipelines were ruptured at Loyalton and Boca Dam. Several bridges on highway 80 retained minor damage, and Boca and Prosser earthfill dams were cracked. Landslides, rockslides, and slumping occured on area highways and on the Southern Pacific Railway bed. This was a main shock in a series occuring near Boca. It was felt over a large area of east-central California and northwest Nevada.
Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.