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Docs on deadly central Japan mudslide show local gov't failure to take precautionary action

Shizuoka Vice Gov. Takashi Namba provides explanations on disclosed documents at the Shizuoka Prefectural Government building in the city of Shizuoka's Aoi Ward on Oct. 18, 2021. (Mainichi/Shota Kaneko)

Recently disclosed documents detailing the administrative procedures taken for the soil mounds that were the origins of a deadly mudslide that struck the central Japan city of Atami in July have revealed that local governments failed to enforce effective measures while recognizing the potential threat posed by the soil.

    The mudslide occurred in Atami, Shizuoka Prefecture, on July 3. The disaster resulted in 26 deaths, while one person remains missing. On Oct. 18, the Shizuoka Prefectural Government disclosed about 4,300 pages of documents created by the prefectural and municipal governments in 2006 or later. While the former and current landowners are said to have not taken any safety measures for the soil mounds, prefectural and municipal authorities also did not take effective action. Parties close to the matter have claimed that the mudslide was a "man-made calamity."

    The origin of the mudslide was situated in the uppermost area of the Aizome River, located some two kilometers from the Pacific coast. A real estate management company, which had undergone liquidation and is situated in the Kanagawa Prefectural city of Odawara, obtained the entire vicinity, including the site of the mudslide, in 2006. The land was transferred to its current owner in February 2011.

    According to the prefectural government's survey, the former owner had filed a notice with the Atami Municipal Government in 2007 that the soil mound had a height of 15 meters, and had a volume of some 36,000 cubic meters. However, it is believed that prior to the mudslide's occurrence, the mound's height was actually some 50 meters, while the total volume was a maximum of 75,000 cubic meters. Based on new calculations by the prefecture using topographic map data, if the soil mound had been 15 meters tall as claimed in the former landowner's notice, then the mound could have consisted of only around 6,000 to 8,500 cubic meters of sediment.

    Yuji Seshimo, right, head of a group of survivors and bereaved family members of the mudslide disaster in Atami and lawyer Hirotaro Kato, center, are seen during a press conference in Tokyo's Minato Ward on Oct. 18, 2021. (Mainichi/Rinnosuke Fukano)

    Atami Mayor Sakae Saito says he first recognized the soil mound's danger in April 2011. At the time, the municipal government had requested in writing that the former owner submit a report indicating the amount of soil brought in, among other factors, based on an ordinance regulating the collection of prefectural soil. As there was no response from the former owner, the city decided to issue an authoritative order in June that commanded the owner to take action. However, as the former owner began disaster prevention construction work in the following July as part of preventative measures against the outflow of sediment, the city apparently called off the order.

    Mayor Saito explained that he did not issue the order as "while it was inadequate, the former owner carried out the disaster prevention construction work, and the current owner also stated firmly that they would conduct additional construction work." He added, "It was a clever tactic to avoid administrative measures, and it is true that we are regretful. Although at the time we judged that our decision to be the right one, we feel ashamed now."

    Would the mudslide disaster have been prevented had the order been issued? Shizuoka Vice Gov. Takashi Namba only went so far as to say, "We gave out instructions many times, but they did not obey them. Whether the other party obeyed and acted in conformity with these instructions is a separate problem."

    The Shizuoka prefectural Atami civil engineering office, the Shizuoka prefectural eastern agriculture and forestry office, and the Atami Municipal Government discussed measures surrounding soil mounds in December 2009. Though some suggested it "may in a worst-case scenario be good to prepare for enforcing a substitute execution by administration," this did not happen. The prefectural government had confirmed in an on-site investigation in August 2010 that the soil mounds comprised eight or nine layers, with an estimated height of 40 to 45 meters -- greatly outstripping the height of 15 meters reported in the notice filed to the government.

    (Japanese original by Hideyuki Yamada, Shota Kaneko and Rinnosuke Fukano, Shizuoka Bureau; and Yoshihiro Yanagawa, Ito Local Bureau)

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