The wave is called a tsunami.
Tsunami waves are produced when a volcanic eruption or earth quake occurs in the ocean.
Tsunami waves are usually giant waves . when they are produced far out in the ocean, they are not all that tall. What happens is that as they begin to move from far out in the ocean towards the coast, they begin getting taller and taller the depth of the sea floor reduces and the sea gets shallower and shallower. By time they reach land they may be dozens of feet high.
They also move at terrific speed especially over deep waters, almost as fast as a jet plane. They only begin to slow down as they approach land but even then the speed is still tremendous.
