Many people have become interested in finding out more about Tsunamis due to the recent and devastating tsunami in Japan. This particular Tsunami was caused by a violent earthquake that occurred below the surface of the ocean. However, not all tsunamis are caused by earthquakes. A tsunami is a series of waves that are made in an ocean or other body of water such as an inland sea or lake. Tsunamis are huge and can travel large distances very quickly. As they approach a coastline they slow down and gain height. Tsunamis can appear as a rapidly rising or falling tide or a series of large waves up to 30 meters in height.
What Causes Tsunamis?
Tsunamis are generally caused by seismic activity of some kind whether that be an earthquake or a volcanic eruption. They can also be caused by an underwater landslide or a meteoroid impact. Tsunamis that are caused by an earthquake are the most common. It all begins when two tectonic plates come in contact with one another underneath the ocean or other body of water. One plate slides under the other and become stuck in a certain place. The plates continue to move and this builds up a large amount of force causing the rock around the area where the plates are stuck to become distorted. The force eventually builds up along the section of rock that is stuck and the overriding plate suddenly slides back into its original position. This creates an earthquake and displaces the overlying water. The wave begins to travel outwards from where the earthquake occurred.
Tsunamis that are caused by volcanic eruption are usually caused by an old magma chamber collapsing. This causes a large depression to form in the ocean floor very quickly. Water rushes into this new depression causing a displacement wave, which can trigger a tsunami.