The Volcano is where a lot of seismic activity took place. Ginger was in a movie once where she was thrown into a volcano, but it had a happy ending. It made 3 million dollars.
At one point the volcano was so furious that the Professor had to build a bomb to de-activate the eruption. Unfortunately, Gilligan and Ginger had fallen into a tunnel leading into the core of the volcano. The Skipper and the Professor carried the bomb to a vent and dropped the explosive device in. Gilligan (being inside), caught the bomb and threw it back. Skipper went to look inside the hole and fell in. The Professor rescued all three of them just as the bomb went off. The Professor's bomb had worked and snuffed out the erupting volcano.