Earthquakes and Tsunamis
Usually, Earth’s crust moves very slowly — only a few millimeters every year. Sometimes, two pieces of the crust move suddenly in different directions, and then there’s an earthquake.
Earthquakes are dangerous because buildings sometimes fall down. When there’s an earthquake, people in buildings go under a heavy table. Or they stand between two rooms. These are good ideas — they can help to keep people safe.
There are earthquakes under the ocean, too. Usually, they are small and not dangerous. Sometimes an earthquake under the ocean makes a giant wave called a tsunami. Tsunamis can be very dangerous.
After a tsunami, there are often floods. There’s water everywhere. Houses, cars, and trees are in the water. The water isn’t clean, so many people are sick. In 2004, there was a very big tsunami in the Indian Ocean. Many people died.