Mudslides stretched about more than 2 km in Atami, Shizuoka Pref. Officials say at least 54,000 cubic meters had been used to fill a valley in roughly the area where the mudslide began.

“The primary factor (behind the disaster) was the insufficient assessment and guidance on the part of the Atami city government,” the body said May 13 in its final report. The Shizuoka ...