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Brinty · 10-06-2008, 06:19 AM

It's not so much the height of a tidal surge or tsunami that is the thing that causes the damage, but the wavelength from trough to trough. Imagine a swell that is say, 5 metres high with a distance of 100 metres between troughs. For ease of explanation, and using a mathematical formula, picture this swell as a triangle 100 metres at the base and 5 metres to the top. You would finish up with an amount of water that would be contained in a rectangle 50 meters by 5 metres or, put another way, 250 cubic metres of water for every metre of the wave's width.

A cubic metre of seawater weighs over a tonne so if a wave was of the dimensions mentioned above, there would be the pressure of 250 tonnes pouring onto the east coast for every metre width. Increase the wavelength by tenfold to 1 kilometre and the weight of water would also be multiplied ten times to 2500 tonnes per metre width.

Scary eh? But we've left one other factor out of the scenario - the speed the wave is travelling at. If it were travelling at say, 100 kph, can you imagine the effect it would have? How far inland it would travel? Think on it this way - there is a mass of water weighing 2500 tonnes traveling at 100kph and it is 500 metres long.

If you still have difficulty with that picture, then imagine a runaway train that is 500 metres long consisting of a string of carriages five metres high and filled with water, travelling at 100kph. Now imagine a wall of these runaway trains, side by side for as far as the eye can see.

If it weren't for The Great Dividing Range, I reckon Alice Springs could get a tad damp.

10-06-2008, 06:19 AM	#104
Brinty Avalon Senior Member Join Date: Sep 2008 Location: Blackbutt, Queensland, Australia Posts: 1,004	Re: Australian Ground Crew Members? It's not so much the height of a tidal surge or tsunami that is the thing that causes the damage, but the wavelength from trough to trough. Imagine a swell that is say, 5 metres high with a distance of 100 metres between troughs. For ease of explanation, and using a mathematical formula, picture this swell as a triangle 100 metres at the base and 5 metres to the top. You would finish up with an amount of water that would be contained in a rectangle 50 meters by 5 metres or, put another way, 250 cubic metres of water for every metre of the wave's width. A cubic metre of seawater weighs over a tonne so if a wave was of the dimensions mentioned above, there would be the pressure of 250 tonnes pouring onto the east coast for every metre width. Increase the wavelength by tenfold to 1 kilometre and the weight of water would also be multiplied ten times to 2500 tonnes per metre width. Scary eh? But we've left one other factor out of the scenario - the speed the wave is travelling at. If it were travelling at say, 100 kph, can you imagine the effect it would have? How far inland it would travel? Think on it this way - there is a mass of water weighing 2500 tonnes traveling at 100kph and it is 500 metres long. If you still have difficulty with that picture, then imagine a runaway train that is 500 metres long consisting of a string of carriages five metres high and filled with water, travelling at 100kph. Now imagine a wall of these runaway trains, side by side for as far as the eye can see. If it weren't for The Great Dividing Range, I reckon Alice Springs could get a tad damp.