Debris flow disaster in Atami, Japan, in July 2021

On the morning of July 3, 2021, a large debris flow occurred at the Aizome River in the Izusan district of Atami, Shizuoka Prefecture, Japan. The debris flow caused extensive damage, causing the death of 26 people, leaving one person missing, and damaging 128 houses (as of October 1, 2021). Consistently steep channel gradient from initiation zone to river mouth resulted in the extensive damage along the river. The debris flow was characterized by its high fine-grained content, which may have affected the flow characteristics. The debris flow comprised multiple surges with different flow characteristics.