( Earthquakes ( ( are ( measured ( on ( ( a variety ) ( of ( scales ( that ( attempt ( to ( describe ( their ( ( magnitude and ) intensity ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Earthquakes)) (VP (VBP are) (VP (VBN measured) (PP (IN on) (NP (NP (DT a) (NN variety)) (PP (IN of) (NP (NP (NNS scales)) (SBAR (WHNP (WDT that)) (S (VP (VBP attempt) (S (VP (TO to) (VP (VB describe) (NP (PRP$ their) (NN magnitude) (CC and) (NN intensity)))))))))))))) (. .)))
Earthquakes are measured on a variety of scales that attempt to describe their magnitude and intensity.
(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.