( ( A tsunami ) ( ( is ( ( a wave ) ( generated ( by ( ( ( a ( submarine ( ( -LRB- ( underwater -RRB- ) ) earthquake ) ) ) or ) ( volcanic event ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN tsunami)) (VP (VBZ is) (NP (NP (DT a) (NN wave)) (VP (VBN generated) (PP (IN by) (NP (NP (DT a) (NN submarine) (PRN (-LRB- -LRB-) (NP (NNP underwater)) (-RRB- -RRB-)) (NN earthquake)) (CC or) (NP (JJ volcanic) (NN event))))))) (. .)))
A tsunami is a wave generated by a submarine (underwater) earthquake or volcanic event.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN underwater) (NN earthquake)) (VP (VBZ creates) (NP (DT a) (NN tsunami))) (. .)))