Collapse, Sinking, Depression
Noun and する verb
かんぼつ
地震であそこの道路が陥没したそうです。
It looks like that highway over there collapsed from the earthquake.
A cave in where everyone dies is still a cave in, just a really sad one.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.