崩壊
ほうかい · houkai · JLPT N1 · noun
collapse
🏚️ 崩 = crumble + 壊 = break: a structure crumbling and breaking into pieces
Both characters mean breaking apart: 崩 (ほう, crumble, cave in) and 壊 (かい, break, wreck). Physics uses 崩壊 for radioactive decay, where an atom breaks apart into other nuclei.