( ( ( ( ( ( 6 ( -RRB- ( seismic disturbances ) ) ) , ) and ) 7 ) -RRB- ) ( ( surface ( tilt ( on ( volcano slopes ) ) ) ) . ) )
(ROOT (S (NP (NP (CD 6) (JJ -RRB-) (JJ seismic) (NNS disturbances)) (, ,) (CC and) (NP (CD 7)) (-RRB- -RRB-)) (VP (VBP surface) (NP (NP (NN tilt)) (PP (IN on) (NP (NN volcano) (NNS slopes))))) (. .)))
6) seismic disturbances, and 7) surface tilt on volcano slopes.
(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)))) (. .)))