Regarding the large-scale debris flow that occurred in Atami City, Shizuoka Prefecture, Vice Governor Namba of Shizuoka Prefecture held a press conference and stated that "the continuous rain penetrated the embankment and collapsed." He said that the cause was the collapse of the river.
In the large-scale debris flow that occurred in the Izusan district of Atami City on the 3rd of this month, it is believed that the embankment collapsed in the most upstream part of the Aihatsu River and the damage spread, and Shizuoka Prefecture is investigating the cause of the debris flow. I will.
On the 13th, Deputy Governor Namba of Shizuoka Prefecture met and explained the mechanism of the collapse of the embankment, which was found in the previous surveys. Collapsed in a chain from bottom to top. "
According to Vice Governor Namba, the embankment was created in the most upstream part of the Aihatsu River, where water tends to collect, and in Atami City, the cumulative total from the 1st to the 3rd of this month before the debris flow occurred, which is the largest in the last 10 years. It means that it rained 449 mm.
In addition, it seems that the embankment had insufficient safety measures to prevent the collapse and runoff of sediment, and that almost no trace of a large-scale landslide was confirmed outside the embankment.
For this reason, Vice Governor Namba said that the debris flow was caused by the collapse of the embankment in the upper reaches of the river.
According to the prefecture, a part of the embankment remains, but "the risk of immediate collapse is low", and we are taking measures to prevent secondary disasters.