( ( ( ( ( Electronic tiltmeters ) , ) ( which ( ( are widely ) ( used ( in Hawaii ) ) ) ) ) , ) ( ( ( measure changes ) ( in ( ( ( slope or ) inclination ) ( of ( the ( ground surface ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Electronic) (NNS tiltmeters)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (ADVP (RB widely)) (VP (VBN used) (PP (IN in) (NP (NNP Hawaii))))))) (, ,)) (VP (VB measure) (NP (NNS changes)) (PP (IN in) (NP (NP (NN slope) (CC or) (NN inclination)) (PP (IN of) (NP (DT the) (NN ground) (NN surface)))))) (. .)))
Electronic tiltmeters , which are widely used in Hawaii, measure changes in slope or inclination of the ground surface.
(ROOT (S (NP (NNS Tiltmeters)) (VP (VBP are) (VP (VBN used) (S (VP (TO to) (VP (VB measure) (NP (NP (DT the) (NN angle)) (PP (IN of) (NP (NP (DT the) (NN slope)) (PP (IN of) (NP (DT a) (NN volcano))))))))))) (. .)))