( ( Underwater earthquakes ) ( ( pose ( ( a threat ) ( of ( ( generating tsunamis ) ( which ( could ( have ( ( a ( devastating effect ) ) ( on ( the ( Caribbean islands ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Underwater) (NNS earthquakes)) (VP (VBP pose) (NP (NP (DT a) (NN threat)) (PP (IN of) (NP (NP (VBG generating) (NNS tsunamis)) (SBAR (WHNP (WDT which)) (S (VP (MD could) (VP (VB have) (NP (NP (DT a) (JJ devastating) (NN effect)) (PP (IN on) (NP (DT the) (JJ Caribbean) (NNS islands)))))))))))) (. .)))
Underwater earthquakes pose a threat of generating tsunamis which could have a devastating effect on the Caribbean islands.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN underwater) (NN earthquake)) (VP (VBZ creates) (NP (DT a) (NN tsunami))) (. .)))