Page 2 - Microsoft Word - 12.3 TSUNAMI AND CYCLONE

What happens during a tsunami?

1. Once the water is moved by an earthquake or other event, large waves like ripples spread out
from the point where the water first moved.
2. These waves can move quickly and for very long distances. Some tsunamis have been known to
travel for thousands of miles across the ocean and travel at speeds of up to 500 miles per hour.
3. As the waves travel through the deep parts of the ocean, their crest is usually short, only a few
feet tall. This makes it difficult to detect a tsunami as they are not necessarily visible in the deep
ocean.
4. When the waves approach land and shallow water, they pile up and grow in height.
5. At the coastline, a trough of the wave may appear. This will cause drawback to occur on the
shoreline. The water may recede for some distance. This can be dangerous as people may be
tempted to walk out into the open area.
6. When the wave arrives on the shore, it will usually be a tall wall of water. The water will rush
inland, sometimes for some distance and with great speed and power. The height of the tsunami
wave will depend on the topography of the shoreline. Some tsunamis have been known to reach
heights of 100 feet.
7. More waves may arrive. The time period between waves may be several minute.