( ( Tiltmeters ( -LRB- ( ( instruments ( ( that ( measure tilting ) ) ( of ( the ground ) ) ) ) -RRB- ) ) ) ( ( help ( detect ( ( ( swelling and ) deflation ) ( of ( ( the volcano ) ( caused ( by ( ( the ( ( accumulation and ) movement ) ) ( of magma ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Tiltmeters)) (PRN (-LRB- -LRB-) (NP (NP (NNS instruments)) (NP (NP (DT that) (NN measure) (NN tilting)) (PP (IN of) (NP (DT the) (NN ground))))) (-RRB- -RRB-))) (VP (VBP help) (VP (VB detect) (NP (NP (VBG swelling) (CC and) (NN deflation)) (PP (IN of) (NP (NP (DT the) (NN volcano)) (VP (VBN caused) (PP (IN by) (NP (NP (DT the) (NN accumulation) (CC and) (NN movement)) (PP (IN of) (NP (NN magma))))))))))) (. .)))
Tiltmeters (instruments that measure tilting of the ground) help detect swelling and deflation of the volcano caused by the accumulation and movement of magma.
(ROOT (S (NP (NP (NNP Instruments)) (SBAR (WHNP (WDT that)) (S (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)))))))))) (VP (VBP are) (VP (VBN called) (NP (NN tilt) (NNS meters)))) (. .)))