How fast can tsunamis travel?

Here is a the final version of how fast can tsunamis travel?

The speed of a tsunami depends on how deep the water is, so the deeper the water, the faster the waves travelling. In very deep oceans a tsunami can travel on speeds of up to 900km per hour, faster than a jet aeroplane.

As it approaches land the shallow water acts as a brake at the front of the wave, slowing it down to around 200km/h. Meanwhile the back of the wave is still travelling very fast as it catches up to the front of the wave. This causes it then to look like a giant wall of water.