( ( Most ( natural earthquakes ) ) ( ( occur ( when ( ( two ( of ( those plates ) ) ) ( ( ( slide ( past ( each other ) ) ) and ) ( ( ( get stuck ) , ) ( ( building up ) pressure ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJS Most) (JJ natural) (NNS earthquakes)) (VP (VBP occur) (SBAR (WHADVP (WRB when)) (S (NP (NP (CD two)) (PP (IN of) (NP (DT those) (NNS plates)))) (VP (VP (VB slide) (PP (IN past) (NP (DT each) (JJ other)))) (CC and) (VP (VB get) (ADJP (JJ stuck)) (, ,) (S (VP (VBG building) (PRT (RP up)) (NP (NN pressure))))))))) (. .)))
Most natural earthquakes occur when two of those plates slide past each other and get stuck, building up pressure.
(ROOT (S (NP (NP (CD Two) (NNS plates)) (VP (VBG sliding))) (VP (MD can) (VP (VB increase) (NP (NP (DT the) (NN occurance)) (PP (IN of) (NP (NNS earthquakes)))))) (. .)))