Bereaved families of Mt. Ontake volcano eruption victims to sue state, Nagano Pref.

Twelve people from five families of those killed in the 2014 eruption of Mount Ontake are set to sue the state and the Nagano Prefectural Government, demanding a total of 150 million yen in compensation, it has been learned.

Mount Ontake, straddling the border between Gifu and Nagano prefectures, erupted in September 2014, claiming 58 lives and leaving five others unaccounted for.

In the lawsuit to be filed with the Matsumoto branch of the Nagano District Court on Jan. 25, the bereaved families of the victims will argue that Mount Ontake's volcanic alert level was not raised from 1 (normal -- at the time of the eruption) to 2 (restricting access to the area around the crater), among other factors.

According to the plaintiffs' arguments and other information, although the Japan Meteorological Agency (JMA) started observing increased volcanic temblors (at least 50 temblors a day), which is one of the criteria for raising the alert level, on Sept. 10, 2014 -- 17 days before Mount Ontake erupted on Sept. 27 that year, the agency decided not to raise the alert level partly on the grounds that the temblors were not accompanied by crustal movements.

The bereaved families of the victims say, "It was inappropriate and led to heavy damage." They also claim that although two of the five seismometers near the mountain peak had been out of order, the Nagano Prefectural Government left them unfixed and that its effort to call people's attention to the eruption was insufficient.

A JMA official in charge said about the decision made by the agency, "We believe that the utmost effort was made to deal with it within the decision criteria." Soon after Mount Ontake erupted, the agency revised the explanatory wording for the alert level 1 from "normal" to "take note that it is an active volcano."