( Tsunamis ( ( are ( ( long-period waves ) ( caused ( by ( ( an ( underwater distubance ) ) ( such ( as ( ( ( a ( submarine earthquake ) ) or ) ( volcanic eruption ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Tsunamis)) (VP (VBP are) (NP (NP (JJ long-period) (NNS waves)) (VP (VBN caused) (PP (IN by) (NP (NP (DT an) (JJ underwater) (NN distubance)) (PP (JJ such) (IN as) (NP (NP (DT a) (JJ submarine) (NN earthquake)) (CC or) (NP (JJ volcanic) (NN eruption))))))))) (. .)))
Tsunamis are long-period waves caused by an underwater distubance such as a submarine earthquake or volcanic eruption.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN underwater) (NN earthquake)) (VP (VBZ creates) (NP (DT a) (NN tsunami))) (. .)))