Please Note: The movies shown on this site have been created to outline the general principles of the creation, propagation and impacts of tsunami - they do not represent any specific event or outcome.
Most tsunami are caused by large earthquakes on the seafloor suddenly moving large bodies of water. The resulting waves move away from the source of the earthquake event at speeds of up to 900 kilometres per hour.
The Indian Ocean Tsunami of 2004 was caused by an undersea earthquake off the coast of Sumatra in Indonesia. Most of the earthquake activity around the world occurs near subduction zones - places where one tectonic plate is forced under another.
Underwater landslides can cause tsunami as can onshore landslides which slump into the ocean.
The 1998 tsunami in northern Papua New Guinea was caused by an earthquake that is believed to have triggered an undersea landslide.
Volcanic tsunamis can be produced by pyroclastic flows (fast-moving curents of hot gas and rock) and/or the collapse of a volcano during a volcanic eruption. Volcano collapse can also occur without an accompanying eruption.
The 1883 eruption of Krakatau volcano in Indonesia unleashed a series of devastating tsunamis that resulted in the loss of tens of thousands of lives.