( ( ( ( ( ( The ( usual causes ) ) ( of tsunami ) ) ( are ( ( earthquakes and ) ( underwater landslides ) ) ) ) but ) ( there ( ( ( is now ) evidence ) ( that ( ( giant tsunami ) ( can ( be ( caused ( by ( NEO impacts ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (JJ usual) (NNS causes)) (PP (IN of) (NP (NN tsunami)))) (VP (VBP are) (NP (NP (NNS earthquakes)) (CC and) (NP (JJ underwater) (NNS landslides))))) (CC but) (S (NP (EX there)) (VP (VBZ is) (ADVP (RB now)) (NP (NN evidence)) (SBAR (IN that) (S (NP (JJ giant) (NN tsunami)) (VP (MD can) (VP (VB be) (VP (VBN caused) (PP (IN by) (NP (NNP NEO) (NNS impacts)))))))))) (. .)))
The usual causes of tsunami are earthquakes and underwater landslides but there is now evidence that giant tsunami can be caused by NEO impacts .
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN underwater) (NN earthquake)) (VP (VBZ creates) (NP (DT a) (NN tsunami))) (. .)))