Most tsunamis are caused by large earthquakes on the seafloor when slabs of rock move past each other suddenly, causing the overlying water to move . The resulting waves move away from the source of the earthquake event. For example, both the 2004 southeast Asia earthquake and the 2011 Great East Japan earthquake caused severe tsunamis . Accident statistics indicate that the combination of earthquakes and tsunamis has destroyed a large amount of hazardous materials facilities.