How are tsunmais formed?

Answer 1

Under the ocean The plates were moving and moving for hundreds of years then finally one of the plates went up about 400ft, which caused an earthquake. That caused a one metre wave and the speed was 500 mph. As the wave started to approach shallow water the shallow water on the beach went way too far back. that made the wave slow down at the front but at the back of the wave the water was still travelling at 500 mph. That made the wave into a vertical wave. so from one metre it went ridiculously high.