Japan has approved the restart of the two reactors at the Kansai Electric Power Ohi nuclear plant, northwest of Tokyo, despite mass public opposition.

They will be the first to come back on line after all reactors were shut following a massive earthquake and tsunami last March that caused the worst nuclear crisis since Chernobyl at Tokyo Electric Power’s Daiichi Fukushima plant.

Seismic modelling by Japan’s nuclear regulator did not properly take into account active fault lines near the Ohi plant, Katsuhiko Ishibashi, a seismologist at Kobe University, told reporters.

“The stress tests and new safety guidelines for restarting nuclear power plants both allow for accidents at plants to occur,” Ishibashi told reporters. “Instead of making standards more strict, they both represent a severe setback in safety standards.”

Experts advising Japan’s nuclear industry had underestimated the seismic threat, Mitsuhisa Watanabe, a tectonic geomorphology professor at Toyo University, said at the same news conference.

“The expertise and neutrality of experts advising Japan’s Nuclear Industrial Safety Agency are highly questionable,” Watanabe said.

After an earthquake in 2007 caused radiation leaks at reactors north of Tokyo, Ishibashi said Japan was at risk of a nuclear disaster following a large earthquake, a warning that proved prescient after Fukushima.

While it is impossible to predict when earthquakes will happen, Ishibashi said on Tuesday the magnitude 9 quake last year made it more likely “devastating” earthquakes would follow.