( ( ( ( Tsunamis , ) ( caused ( by ( underwater earthquakes ) ) ) ) , ) ( ( ( ( have ( devastated ( many islands ) ) ) and ) ( ( in ( some cases ) ) ( destroyed ( entire towns ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Tsunamis)) (, ,) (VP (VBN caused) (PP (IN by) (NP (JJ underwater) (NNS earthquakes)))) (, ,)) (VP (VP (VBP have) (VP (VBN devastated) (NP (JJ many) (NNS islands)))) (CC and) (VP (PP (IN in) (NP (DT some) (NNS cases))) (VBD destroyed) (NP (JJ entire) (NNS towns)))) (. .)))
Tsunamis, caused by underwater earthquakes, have devastated many islands and in some cases destroyed entire towns.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN underwater) (NN earthquake)) (VP (VBZ creates) (NP (DT a) (NN tsunami))) (. .)))