Tsunamis are a force of nature to be reckoned with.
Gigantic waves that decimate the shores they hit.
But what makes them so destructive?
A tsunami is caused by an underwater disturbance.
It's a huge volume of moving water that forms massive waves when it reaches shallow areas.
Tsunami – massive volume of moving water
Tsunamis can be a single wave, but they are usually composed of a series of crests called a wave train.
Landslides, volcanic eruptions, and even meteorites can create a tsunami.
But the most common cause is an undersea earthquake.
When the ocean floor cracks, one side is thrust upwards – a process known as tectonic uplift.
It suddenly displaces the water above the fault.
This creates a ripple that starts to move outwards, racing across the ocean at the speed of a jet plane.
Over 900 km/h
As the tsunami nears shallow water, the front of the wave is slowed down dramatically.
Faster moving water from behind catches up on the front of the wave, causing it to rear up into a wall of water.
Up to 30 metres high
As it approaches the shore, the water along the beach is sucked back towards the tsunami.
Drawback – ocean recedes before a tsunami
When it hits land, the whole length of the wave sweeps forward, engulfing everything in its path.
This is what happened on December 26 2004.
A 1200km section of the Earth's crust shifted off the coast of Sumatra, an island in Indonesia.
Energy released: Over 23,000 atomic bombs
The waves reached up to 30m high, causing huge amounts of damage.
It was one of the most deadly natural disasters in recent history, claiming over 200,000 lives.
Small tsunamis occur frequently, but major waves are very rare, only produced roughly six times a century.
Tsunamis can now be tracked once they start.
Computerised offshore buoys map their paths, giving vital warning to countries likely to be hit.
It is hoped that in the future these warning systems will give enough time to get everyone to safety.