zerfạllen1
intransitive verb
irregular, mit sein 1 (also ) disintegrate (in + Akk., zu into); ‹building› fall into ruin, decay; ‹corpse› decompose, decay;
zerfallende Mauern/Ruinen crumbling walls/ruins;
zu Staub zerfallen crumble into dust;
Moral und Kultur waren zerfallen morals and culture had broken down or fallen into decay
2 (unterteilt sein)
in Phasen/Teile usw. zerfallen be divided into phases/parts etc.
3 (Nuclear physics) decay