Can you imagine the devastation that would be caused if a massive wall of water several hundred feet high slammed into Florida at more than 100 miles an hour? To many people such a scenario is impossible, but that is what people living along the Indian Ocean thought before the 2004 tsunami and that is what people living in Japan thought before the 2011 tsunami. Throughout history, giant tsunamis have been relatively rare events, but they do happen. Scientists tell us that a mega-tsunami can race across the open ocean at up to 500 miles an hour, and when they...