( ( A fault ) ( ( is ( ( a fracture ) ( in ( ( ( the ( earth 's ) ) crust ) ( along ( which ( ( rocks ( on ( one side ) ) ) ( have ( been ( ( displaced ( relative ( to ( the rock ) ) ) ) ( on ( the ( other side ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN fault)) (VP (VBZ is) (NP (NP (DT a) (NN fracture)) (PP (IN in) (NP (NP (NP (DT the) (NN earth) (POS 's)) (NN crust)) (PP (IN along) (SBAR (WHNP (WDT which)) (S (NP (NP (NNS rocks)) (PP (IN on) (NP (CD one) (NN side)))) (VP (VBP have) (VP (VBN been) (VP (VBN displaced) (ADVP (JJ relative) (PP (TO to) (NP (DT the) (NN rock)))) (PP (IN on) (NP (DT the) (JJ other) (NN side))))))))))))) (. .)))
A fault is a fracture in the earth's crust along which rocks on one side have been displaced relative to the rock on the other side.
(ROOT (S (NP (DT A) (NN fault)) (VP (VBZ is) (NP (NP (DT the) (NN fracture)) (VP (VBN caused) (SBAR (WHADVP (WRB when)) (S (NP (NP (NNS rocks)) (PP (IN on) (NP (DT both) (NNS sides)))) (VP (VBP move))))))) (. .)))