The document discusses the physics behind tsunamis, beginning with the causes of earthquakes. It describes plate tectonics and how the movement of tectonic plates can cause earthquakes. It then explains how earthquakes at sea can generate tsunamis by rapidly displacing large amounts of water. The document outlines how tsunami waves travel long distances at high speeds with little loss of energy. Finally, it discusses the impacts of the 2004 Indian Ocean tsunami, including physical changes to coastlines and islands as well as human impacts.