( ( ( ( why and ) how ) ( ( ( ( earthquakes occur ) , ) and ) ( ( the scales ) ( used ( to ( measure ( their ( ( intensity and ) magnitude ) ) ) ) ) ) ) ) . )
(ROOT (FRAG (SBAR (WHADVP (WRB why) (CC and) (WRB how)) (S (S (NP (NNS earthquakes)) (VP (VBP occur))) (, ,) (CC and) (S (NP (DT the) (NNS scales)) (VP (VBD used) (S (VP (TO to) (VP (VB measure) (NP (PRP$ their) (NN intensity) (CC and) (NN magnitude))))))))) (. .)))
why and how earthquakes occur, and the scales used to measure their intensity and magnitude.
(ROOT (S (NP (NNS Seismologists)) (ADVP (RB originally)) (VP (VBD measured) (NP (NP (DT the) (NN intensity)) (PP (IN of) (NP (DT an) (NN earthquake)))) (PP (IN with) (NP (DT the) (JJ mercalli) (NN scale)))) (. .)))
Seismologists originally measured the intensity of an earthquake with the mercalli scale.