(S (S (BASENP (DT The) (NN volcano)) (VP (VBD had) (VP (VP (VP (VBN erupted) (BASENP (NN four) (NNS times))) (PP (IN on) (BASENP (NNP Friday)))) (COMMA ,) (S (VP (VP (VP (VBG billowing) (BASENP (NN ash))) (PRT (RP up))) (PP (TO to) (NP (BASENP (NN 51,000) (NNS feet)) (ADVP (RB up) (PP (IN into) (BASENP (DT the) (NN air))))))))))) (PERIOD .))