南海 なんかいトラフ巨大 きょだい地震 じしんであれば
nankaitorafu kyodai jishindeareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of 南海トラフ巨大地震

1. If/when the Nankai Trough mega-earthquake occurs.; If/when there is a Nankai Trough mega-earthquake.

Ba Conditional