Tidal Waves Page02_ approaching

Only energy is moves through the wave. The actual water molecules are not moved along with the wave. Think of an outstretched slinky. A simple tug on one end can set a wave in motion. The metal rings will move back and forth. Even so, they always return to their original position. This return to equilibrium of matter is a feature of waves.

You may wonder, what is a medium?

A medium is a substance or material through which the wave travels. It is important to note, the medium is not the wave. It is only the material the wave is moving through. In the case of a tidal wave, the medium is water.

. Even in the more viscous fluid of water, the fastest speed is still very impressive. It is hard to imagine a tidal wave traveling as fast as a jet airliner. This leaves very little time for people to get ready. People living along the shore may have only hours or even minutes to prepare. Before people could move to safety, they would first need to know if a tidal wave was coming.

Unfortunately, it’s not as simple as knowing there is an earthquake in the ocean. Not all earthquakes cause tidal waves. Furthermore, tidal waves are very hard to detect out at sea.

If you were on a cruise ship far out at sea, a tidal wave could pass under the boat without anyone knowing.

How is that possible?

In the deep ocean, the wave height may only be inches. The wave only gains height as it enters shallow water. Imagine the fishermen on that infamous day in 2004. They returned home only to find the port and neighboring town scoured by the violent rush of water. The large wavelength of a tidal wave kept the wave hidden to them. It passed without notice right under their boats. The fishermen who returned to their ports had no idea what had happened.