( ( Of ( ( the ( two modes ) ) ( of propagation ) ) ) ( ( ( the ( seismic mode ) ) ( of propagation ) ) ( ( is ( ( the ( more complicated ) ) ( since ( ( the ( same harmonic ) ) ( may ( ( propagate simultaneously ) ( in ( ( ( various ( wave types ) ) ( -LRB- ( ( ( ( ( ( compressional waves ) , ) ( shear waves ) ) and ) ( various ( surface ( wave types ) ) ) ) -RRB- ) ) ) ( with ( differing ( propagation vehicles ) ) ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN Of) (NP (NP (DT the) (CD two) (NNS modes)) (PP (IN of) (NP (NN propagation))))) (NP (NP (DT the) (JJ seismic) (NN mode)) (PP (IN of) (NP (NN propagation)))) (VP (VBZ is) (ADJP (ADJP (DT the) (RBR more) (JJ complicated)) (SBAR (IN since) (S (NP (DT the) (JJ same) (NN harmonic)) (VP (MD may) (VP (VB propagate) (ADVP (RB simultaneously)) (PP (IN in) (NP (NP (NP (JJ various) (NN wave) (NNS types)) (PRN (-LRB- -LRB-) (NP (NP (JJ compressional) (NNS waves)) (, ,) (NP (NN shear) (NNS waves)) (CC and) (NP (JJ various) (NN surface) (NN wave) (NNS types))) (-RRB- -RRB-))) (PP (IN with) (NP (VBG differing) (NN propagation) (NNS vehicles))))))))))) (. .)))
Of the two modes of propagation the seismic mode of propagation is the more complicated since the same harmonic may propagate simultaneously in various wave types (compressional waves, shear waves and various surface wave types) with differing propagation vehicles.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD two) (NNS types)) (PP (IN of) (NP (NN surface) (NNS waves))))) (. .)))