The tsunami was mainly caused by the motion of the earth beneath the sea suddenly. May collapse, landslide Or crust pushed up or collapsing. When the land under the sea born to change shape suddenly.To change the shape of the sea floor often occur when the earthquake due to the movements of the earth's crust. This will cause the edge of crust multiple sheets connected called fault (such as fault)In addition to the earthquake. Landslides often occur in conjunction with underwater earthquakes can cause tsunamis. In addition to a concussion caused underwater. The huge ground collapse into the sea.It can cause a wave. The tsunami happened in this format will shrink down quickly and no effect on the coast is far too much. However, if the land is large enough. May cause a mega tsunami