Tsunami
A tsunami is a series of large ocean waves caused by sudden, large-scale disturbances of water. The primary triggers include submarine earthquakes, volcanic eruptions, underwater landslides, and meteorite impacts. Of these, undersea earthquakes account for the majority of destructive tsunamis worldwide. When the seafloor suddenly shifts during an earthquake, it displaces the water column above it, initiating waves that radiate outward in all directions.
Propagation and Speed
In deep ocean water, tsunami waves travel at speeds of 500–800 kilometers per hour, allowing them to cross entire ocean basins in just a few hours. The wavelength of a tsunami can exceed 100 kilometers, and in deep water the waves may be less than a meter high—often unnoticed by ships at sea. However, as these waves approach shallow coastal waters, the seafloor friction slows them down while conservation of energy causes the wave height to increase dramatically, sometimes reaching heights of 30 meters or more.
Coastal Impact
When a tsunami reaches the shore, it typically manifests as a rapid withdrawal of water followed by a series of destructive waves that surge inland. The impact can cause severe coastal erosion, flooding, and destruction of infrastructure and settlements. The 2004 Indian Ocean tsunami and the 2011 Japan tsunami demonstrated the devastating potential of these events, claiming hundreds of thousands of lives. Modern tsunami warning systems use networks of seismic sensors and ocean buoys to detect earthquakes and waves, providing critical minutes to hours for coastal populations to evacuate.