( ( ( ( Tsunamis ( are ( created ( when ( ( ( ( ( ( an ( underwater earthquake ) ) , ) ( volcanic eruption ) ) or ) ( a landslide ) ) ( suddenly ( disturbs ( ( the ( ocean 's ) ) surface ) ) ) ) ) ) ) ) and ) ( ( the ( ocean floor ) ) ( shifts upwards ) ) ) . )
(ROOT (S (S (NP (NNS Tsunamis)) (VP (VBP are) (VP (VBN created) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT an) (JJ underwater) (NN earthquake)) (, ,) (NP (JJ volcanic) (NN eruption)) (CC or) (NP (DT a) (NN landslide))) (ADVP (RB suddenly)) (VP (VBZ disturbs) (NP (NP (DT the) (NN ocean) (POS 's)) (NN surface)))))))) (CC and) (S (NP (DT the) (NN ocean) (NN floor)) (VP (VBZ shifts) (NP (NNS upwards)))) (. .)))
Tsunamis are created when an underwater earthquake, volcanic eruption or a landslide suddenly disturbs the ocean's surface and the ocean floor shifts upwards.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN underwater) (NN earthquake)) (VP (VBZ creates) (NP (DT a) (NN tsunami))) (. .)))