SENDAI—A high court here on Sept. 30 more than doubled the amount of compensation awarded to victims of the Fukushima nuclear disaster and issued a scathing critique against the central government for its inaction.

The Sendai High Court found the central government equally at fault as plant operator Tokyo Electric Power Co. for failing to take anti-tsunami measures and ordered the defendants to pay a total of about 1.01 billion yen ($9.6 million) to around 3,550 evacuees and residents living in Fukushima Prefecture and elsewhere.

It was the first high court ruling in various lawsuits seeking compensation from TEPCO and the central government for the triple meltdown at the Fukushima No. 1 nuclear power plant caused by a quake-triggered tsunami in March 2011.

In October 2017, the Fukushima District Court ordered the defendants to pay about 500 million yen to about 2,900 evacuees. That decision was appealed to the Sendai High Court, which increased both the compensation amount and the number of recipients.

“We won a total victory over the central government and TEPCO,” Izutaro Managi, a lawyer for the plaintiffs, said. “The effect on the various lawsuits to be decided in the future will be huge.”

A major point of contention in the case was a long-term assessment of the probability of major earthquakes released by the science ministry’s Headquarters for Earthquake Research Promotion in 2002. The report pointed out that Fukushima Prefecture could be hit by a major tsunami.

The high court found the assessment to be a “scientific finding that had a considerable level of objective and rational basis,” making it an important perspective that differed greatly from various views presented by individual scholars or private-sector organizations.

The court ruled that if the economy minister at the time had immediately ordered TEPCO to calculate the height of a possible tsunami, a forecast could have been made of the likelihood of a tsunami striking the nuclear plant.

But the ruling said, “The regulatory authority did not fulfill the role that was expected of it” and that “not exercising regulatory powers was a violation of the law regarding state compensation.”

The Fukushima District Court found that the central government only had a secondary responsibility to oversee the utility.

The high court, however, ruled that the government had the same level of responsibility. It said both the central government and TEPCO avoided making tsunami calculations because they feared the effects that would arise if the urgent measures were taken.

The high court ruling also expanded the range of plaintiffs who could receive compensation to people living in the Aizu district of Fukushima Prefecture as well as Miyagi and Tochigi prefectures where evacuation orders were not issued.

Experts said the high court ruling is a game-changer because of the positive assessment given to the long-term evaluation about possible tsunami.

Other district courts have ruled that the central government was not responsible because even if it had ordered measures to be taken, there would not have been enough time to complete such steps to prevent damage from the tsunami.

“Plaintiffs in the other lawsuits have provided testimony at a similar level so this could turn the tide in the recent trend of plaintiffs losing their cases,” said Masafumi Yokemoto, a professor of environmental policy at Osaka City University who is knowledgeable about nuclear plant issues.

Yotaro Hatamura, a professor emeritus of engineering at the University of Tokyo who headed the government panel that investigated the Fukushima nuclear accident, said, “This was an unprecedented ruling that pointed out in a rational manner the stance of both the central government and TEPCO of not looking at data that they did not want to see.”

Chief Cabinet Secretary Katsunobu Kato said at his Sept. 30 news conference that the central government would carefully go over the court ruling before making a decision on whether to appeal.

TEPCO also issued a statement with similar wording.

(This article was written by Taro Kotegawa and Keiji Iijima.)