Definition: 

A tsunami is a series of large ocean waves caused by sudden disturbances in or near a body of water, often triggered by underwater earthquakes, volcanic eruptions, or landslides.


Explanation: 

In geography, a tsunami is a powerful natural phenomenon where massive waves are generated due to events like tectonic plate movements under the ocean floor. These waves can travel across entire oceans at high speeds and cause significant destruction when they reach coastal areas, flooding land and damaging infrastructure. Unlike regular waves, tsunamis have much longer wavelengths and can carry enormous energy, making them highly destructive.


Example: 

If an earthquake happens under the Pacific Ocean, it can push the water upward, creating huge waves. These waves might travel thousands of miles and hit a coastline, like the 2004 Indian Ocean tsunami that flooded coastal areas in countries like India, Sri Lanka, and Thailand.