4 CHAPTER 1 HOW TSUNAMIS FORM A tsunami is a group of huge waves that hit land Most tsunamis are caused by earthquakes These earthquakes happen deep underwater The ocean floor is made up of many tectonic plates WATCH A VIDEO HERE
5 These huge plates move very slowly Sometimes two plates run into each other When that happens those plates can cause an earthquake A diver swims in a gap between two of Earth's tectonic plates
6 An ocean earthquake causes waves At first these waves are small and fast But the ocean is shallower near the shore The waves slow down as they
7 Tsunami waves often start less than a foot tall Near shore they can become more than 100 feet tall hit the shallow water As these waves slow down they get taller When a tsunami finally strikes land the waves can be massive
