tsunami, original a japanese word, is now the standard term for what used to be called a tidal wave. since tsunami are not generated by tidal forces, and since tsumani means 'great wave' it is a more acurate term.

we have discussed some oceographic terms, but in WOW's link over in I & A, the term bore is used.

tidal bores (are there other kinds?) are well known.

if a river bed has a drop in it.. (a substanstial drop, but not one that causes a water fall.)

________****____water level of river (*=a surface disturbence)
-------_________(river bed)

AND this change in river bed level is close enough to the mouth, you can get a tidal bore.

the sudden change in the river bed depth, (and low tide--this might actually present as a small water fall, or rapids)impedes the back flow of (upstream flow)the tide. as the tide comes in, it fills the river bed right up to change in depth, and as it 'tops' over the step, there is a surge of tidal water..this surge of water is a tidal bore--one of the reasons for a bore is how water volume moves during a tidal flow.

the best known bore in North America is on one of the rivers that feeds the bay of fundy..(which is known for its extreme tides)
tidal movement of water is very interesting.

tides water moves by 'the rule of 12'
in the six hours or so it takes for a tide to 'change' the water moves in 1/12ths..

in the 1st hour, 1/12ths of the volume of water is moved
in the 2nd hour, 2/12ths of the volume of water is moved.
in the 3rd hour, 3 /12ths of the volume of water is moved.
in the 4th hour, 3/12ths of the volume of water is moved.
in the 5th hour, 2/12ths of the volume of water is moved.
in the 6th hour, 1/12th of the volume of water is moved.

So in the 'middle 2 hours' (1/3 of the time)6/12ths (or 1/2) of the volume of water is moved!

furthermore, in the of the middle two hours, (3.5 to 4.5)--4/12ths (1/4th or 25%) of the water is moved.

i wonder if the tide was high or close to high tide, the effect of a tsunami were much worse, (there would have been more water closer to shore) and if an area was at low tide, its might have mitigated the effects of waves--there wasn't (that i saw) any information about the tides.

in looking at all the images of the 'path' of the tsunami, and the areas that suffered destructions (why were some parts of the eastern coast of india impacted so much more than others?) i wonder what effects the local tides had.

now that i have shared a large percentage of my water knowlege.. perhaps we can explore other specific terms for water (and water movement in rivers, lakes and oceans..)

or is the idea to boring?




my other obsession