Tsunami as fast as a jumbo jet

QUESTION

The tsunami that struck Indonesia was said to have travelled at more than 400 mph, but this was not the speed it hit the shore. What part of a tsunami can reach that velocity?

A TSUNAMI occurs when the water in the ocean is displaced by an earthquake or volcano. Like throwing a stone into a pond, a series of waves are generated.

On a boat in the ocean, you might hardly notice a tsunami because its energy is distributed throughout the water and the surface wave will be less than a metre high.

The speed of the tsunami is equal to the square root of the acceleration due to gravity (a constant 9.81 metres per second) times the water depth at which the disturbance occurred.

In the ocean, this would be 500mph — the speed of a jumbo jet. In 1960, a tsunami triggered by an 8.8magnitude earthquake in Chile took 21 hours to reach Japan, 10,500 miles away.

As a tsunami wave hits the shoreline, it rapidly slows down to 30mph, but the back of the wave is travelling faster and catches up. The water is forced upwards, building a destructive wave that’s 30ft to 100ft high. Dr Ian Smith, Cambridge.

QUESTION

Was Jackie Gleason, aka Sheriff Buford T. Justice in Smokey And The Bandit, a successful composer?

THE previous answer about Gleason’s albums mentioned his quick wit — he was also known for his bulk and party lifestyle.

He famously said: ‘The second day of a diet is always easier than the first. By the second day you’re off it.

‘Thin people are beautiful, but fat people are adorable.’ Jane Saunders, Manchester.