A fault near Hokuriku Electric Power Co.'s Shiga nuclear plant may be active and the utility should consider bolstering the facility's quake-resistance, a study found Thursday.
The study by professors Mitsuhisa Watanabe of Toyo University and Yasuhiro Suzuki of Nagoya University found that the fault 9 km north of the plant in Ishikawa Prefecture had shifted in the last 120,000 to 130,000 years, a time frame that prompted the government to recommend that reactor operators take a new look at such movements.
Movement of a fault may trigger a stronger than forecast earthquake to strike near the power plant, thus closer study is needed, they said.
The professors believe terraces at different elevations that formed on once flat land around the fault in the coastal area indicate repeated fault movements.
Traces of abrupt land elevation also found in the coast near the plant are "evidence of fault activities, which have been continuing for several thousands of years," Watanabe said.
The fault has been known since the 1970s, but it has never been clearly recognized as active.
Hokuriku Electric officials said the fault is not active and should not affect the safety of the Shiga complex. The two reactors at the plant have been offline since being halted last year for regular maintenance.