Jon ran as the tunnel collapsed behind him.
( Jon ( ( ran ( as ( ( the tunnel ) ( collapsed ( behind him ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Jon)) (VP (VBD ran) (SBAR (IN as) (S (NP (DT the) (NN tunnel)) (VP (VBD collapsed) (PP (IN behind) (NP (PRP him))))))) (. .)))
The tunnel collapsed behind Jon as he ran.
( ( The tunnel ) ( ( ( collapsed ( behind Jon ) ) ( as ( he ran ) ) ) . ) )
(ROOT (S (NP (DT The) (NN tunnel)) (VP (VBD collapsed) (PP (IN behind) (NP (NNP Jon))) (SBAR (IN as) (S (NP (PRP he)) (VP (VBD ran))))) (. .)))