debris flow; mudslide; landslide
Geological term for a rapid flow of water-saturated earth, rocks, and debris, often triggered by heavy rain or volcanic activity. In everyday news, it is often used interchangeably with 土砂崩れ, but 土石流 specifically emphasizes the flowing mixture of soil and rocks.
A debris flow occurred due to heavy rain, cutting off the road.
This area has a high risk of debris flows.