cave-in; collapse; sinking; depression (e.g., of land, road, or the skull); subsidence
大雨の影響で道路が陥没した。
The road collapsed/sank due to heavy rain.
事故で頭蓋骨が陥没し、手術が必要になった。
The skull was depressed in the accident and surgery was required.
地下工事のせいで地盤が陥没する恐れがある。
There is a risk of ground subsidence due to the underground construction.