海啸，为什么在海上看着不高？

A tsunami starts under the sea. 海啸是从海底开始的。 Far out at sea, the wave is only one meter high. 在深海里，浪只有一米高。 Ships barely even notice it. 船上的人几乎感觉不到。 But the water moves very, very fast. 可海水跑起来又快又猛。 Near the beach, the wave piles up. 冲到岸边，浪头越堆越高。 It can become a wall tens of meters high. 它能变成几十米高的水墙。