"A 9.0 quake happens once every 20 years, like the one that struck Japan in March. An earthquake of 10.0 has never been recorded in history and it is said to occur once every 2500 years, capable of destroying entire civilizations. We'll see what would unfold if a 10.0 Megaquake struck different fault lines in the U.S., underwater and around the world"--History Channel website.
