Imagine a wall of water over 1,000 feet high racing toward shore. This isn’t science fiction—it’s a potential reality. Scientists warn that parts of the U.S. could one day face mega-tsunamis, rare disasters caused not just by earthquakes, but by massive landslides or volcanic collapses. What Is a Mega-Tsunami?Unlike typical tsunamis caused by underwater quakes, mega-tsunamis result from enormous chunks...