(S (S (S (BASENP (DT The) (FW tsunami) (NNS warnings)) (VP (VBD were) (VP (VBN issued)))) (SBAR (RB only) (SBAR (IN after) (S (NP (BASENP (NNP Japan) (POS 's)) (BASENP (NN weather) (NN agency))) (VP (VBD said) (SBAR (IN that) (S (NP (DT an) (NP (ADJP (JJ 18-inch) (PRN (LRB -LRB-) (BASENP (NN 46cm)) (RRB -RRB-))) (NN wave))) (VP (MD could) (VP (VB be) (BASENP (DT a) (NN possibility))))))))))) (PERIOD .))