Tsunamis are ocean waves generated by a disturbance in the sea floor. The waves can reach huge heights and speeds while traveling vast distances.
A tsunami is most commonly triggered by an underwater earthquake, but can also be caused by landslides, volcanic eruptions, or even explosions.
Geologists say tsunamis often pick up strength and speed as they travel and they become even more powerful close to shore, where the water is shallower.
Tsunamis can pummel coastlines with walls of water meters high, washing away homes and buildings, and triggering heavy flooding.
Tsunamis can form and travel outwards in all directions from the epicenter of an earthquake, meaning they can affect countries thousands of kilometers apart.
Some information for this report provided by AFP and AP.