Alaska:In 1958, an earthquake-triggered landslide in Lituya Bay created a wave over 1,700 feet high—the tallest ever recorded. As glaciers melt and permafrost thaws, similar disasters could recur. Hawaii:Volcanic slopes, like those on Mauna Loa and Kilauea, are unstable. Past undersea landslides suggest ancient mega-tsunamis once hit the islands. A sudden collapse could again send massive waves across the Pacific....