There are 14 potentially active fault lines in areas near the crisis-hit Fukushima No. 1 nuclear power plant and other nuclear-related facilities, the government has announced.
The Nuclear and Industrial Safety Agency announced the results of research undertaken by power utilities following the Great East Japan Earthquake.
The 14 faults discovered to be potentially active were previously considered unlikely to cause earthquakes.
According to the research, a magnitude-7.6 earthquake could occur on the potentially active Hatakawa fault line in Fukushima Prefecture, the largest magnitude earthquake estimated.
The agency said the intensity of any quakes from the fault lines would not exceed the level the facilities were designed to withstand. It also said there were no problems with the facilities' quake resistance.
Five of the 14 fault lines are near Tokyo Electric Power Co.'s Fukushima No. 1 and No. 2 nuclear power plants.
The other nine are near Japan Atomic Power Co.'s Tokai No. 2 power plant and the Japan Atomic Energy Agency's Tokai reprocessing plant in Ibaraki Prefecture.