(S (S (PP (VBG According) (PP (TO to) (BASENP (DT the) (NNP Observatory)))) (COMMA ,) (S (BASENP (JJ seismic) (NN activity)) (VP (VBD caused) (S (NP (BASENP (DT a) (JJ major) (NN lahar)) (PRN (COMMA ,) (ADJP (JJ similar) (PP (TO to) (BASENP (DT a) (NN mudslide) (CC or) (NN landslide)))) (COMMA ,))) (VP (TO to) (VP (VB occur) (PP (IN in) (BASENP (DT the) (NNP Drift) (NNP River) (NNP Valley))))))))) (PERIOD .))