Mary Cashman, age 10, of San Francisco, California, for her question:

What starts a tidal wave?

High tides wash up on the beaches twice every day and some are higher than others. Once in a great while, huge wild waves come flooding in over the land, creating disastrous destruction for miles and miles. We call this a tidal wave, though usually it has nothing to do with the regular daily tides. Sometimes it happens when a howling hurricane blows floods of ocean water onto the land, bashing down trees and buildings.

Sometimes earthquakes tremble and volcanoes erupt deep down on the floor below the oceans. This upsets the sea and causes the water. to rise and fall in monstrous waves. These enormous waves spread on and on until they reach the shores. Then they come raging in over the land. This sort of tidal event is called a tsunami. Tidal waves caused by raging storm winds also may be called tsunamis. Tsunami is a Japanese word for storm wave and you say with a small, soft "T" sound.