Scientists offer insight into how and where a 10.0 megaquake could strike. This two-hour History special explores one of the most deadly and perplexing mysteries that surrounds planet earth: huge megaquakes. The largest quake ever recorded was a 9.5 earthquake off of Chile in 1960, but new research shows how even larger quakes close to 10.0 just might be possible. Through interviews with top earthquake experts and cutting edge scientific experiments, the special reveals that over 3 billion people on earth are in immediate danger from the next big one and how a real 10.0 might actually happen on US soil--in places you might not expect.