Avoiding a catastrophe if Mount Fuji erupts after major quake

What would happen if Mount Fuji suddenly erupted following a major earthquake?

A large majority of the general public in Japan considers the likelihood of it occurring in the foreseeable future extremely low.

But it did happen three centuries ago, and experts say it is a possibility that should be taken seriously through advanced preparations and drills, in order to avoid a major catastrophe in a situation that would already be out of control.