YM out of its depth ..... again?

[Greenwichman]

March edition page 13, diagram 'anatomy of a tsunami' shows waves forming at sea and travelling towards shallow water. Oh, yes? At 300 knots? Pity they couldn't get an expert who knows about these things. But then the guy's name is Disney, apparently. /forums/images/graemlins/smirk.gif

 

[Birdseye]

[ QUOTE ]
March edition page 13, diagram 'anatomy of a tsunami' shows waves forming at sea and travelling towards shallow water. Oh, yes? At 300 knots? Pity they couldn't get an expert who knows about these things. But then the guy's name is Disney, apparently. /forums/images/graemlins/smirk.gif

[/ QUOTE ]

So what is wrong about the report? Its well established that waves like the Tsunami in very deep water, with a long wavelength can travel at very high speeds (as much as 500 mph in the deepest part of the Pacific), slowing down as the water shallows and the wave height builds.

Have a read of this

 

[jimi]

erm I'd checkyour facts out if I were yoiu

 

[webcraft]

Facts are chiels that winna ding

- R. Burns

 

[graham]

Not widely known but a Tsunami came up the Bristol channel in 1607causing lots of catatrophe at huntspill ,brean and several other communities.

at appledore a large ship ended up well above normal HW level.

The wave was an estimatedc 18 feet ,I think its not the height but the length of Tsunamis that cause such devastation .A normal 18 ft wave would break harmlessly on the beach but these buggers just keep coming forward .

 

[Woodentop]

The problem lies with the word "Wave".

This makes you think of a nice curved shape on the surface of the water. This is not the case.

What we have have is a shock-wave opr pulse travelling through the water, with little indication or trace of it at the surface.

Pre asia tsunami models predicted a speed for the wave of 300-400 knots.

 

[Greenwichman]

Thanks, Woodentop, my point exactly.

The way the YM description is phrased (and the diagram that goes with it) implies that actual watery wet waves leap across the ocean and heap up on the shoreline. They don't.

Vessels at sea in deep water feel absolutely nothing.

Those in shallower water and relatively close to the epicentre may hear grinding vibrating noises (as friends of mine in a tanker in the Malacca Strait reported on Boxing Day: in fact, they were so alarmed they took all way off their ship, thinking they had gone aground).

 

[Woodentop]

What ! You agree with me !

Not having read the latest "Overseas Charters and If I Get Out Of The Solent" Monthly I thought your arguement was about wave speed.

When researching my reply I was suprised by wave speed. The speed of sound in air is about 600 knots (pressure and temperature and altitude vary this) but the speed in water is about 2,000 knots.

I thought that a much higher speed than 400 knots would apply to the shock wave.

Also there are a number of accounts from Japanese fishermen who had a happy day at sea to find their home port had been wrecked by a wave that passed beneath them at sea, without their knowledge.

Your point exactly.