Pacific Gas & Electric Company went through six years of hearings , referenda and litigation to have the Diablo Canyon plant approved . A principal concern about the plant is whether it can be sufficiently earthquake-proof ; the site was deemed safe when construction began in 1968 , but a seismic fault ( the Hosgri fault ) had been discovered several miles offshore by the time the plant was completed in 1973 . This fault experienced a 7.1 magnitude quake 10 miles offshore on November 4 , 1927 , and thus is capable of generating forces equivalent to approximately 1/16 of those felt in the 1906 San Francisco earthquake
1906 San Francisco earthquake
1906 San Francisco earthquake
Diablo Canyon Power Plant