Tsunami

A few little things about Tsunami

1. The Tsunami that hit recently was caused by a subduction earthquake due to natural plate tectonics. The earthquake was not predictable with any accuracy at all! Similarly the Tsunami was also not predictable. Oil and gas activities as well as global warming had no effects. I can see why someone started these rumours on the internet. as the film the day after tomorrow showed a Tsunami and oil and gas exploration use seismic sensors which are in use in the Indian ocean. But these are totally erroneous and to be forgotten.

2. A Tsunami is a very different wave from those normally in the sea. I think that a good analogy is a pond with some wind generated ripples on the surface. They generally go in one direction at the same speed and with the same height etc. But if you throw a pebble in to the pond the ripples this create can be larger or smaller than the other ripples (depending on the size of the pebble) which can move at a speed independent of the other ripples. The new ripples also move out from the drop point in all directions. this is the same as a tsunami apart from instead of a pebble. The water surface was distorted by water pressure change in the ocean above a subduction zone.

3. The Tsunami wave contained far more energy than the normal Indian Ocean wave. But wave energy does not mean more wave height. instead they lead to a wave which has greater influence below the surface and penetrates deeper than the surrounding waves. They move faster than expected (I understand the recent Tsunami moved at nearing 500mph). in the ocean these waves are hard to spot especially with insitu wave sensors. As they come close to shore the deepest part of a wave influence would hit the seafloor and start to be pushed up making the wave height increase also. as with a normal wave. at a certain point on a beach the wave crashes and a face of wave rushes ashore in a bubble of turbulence. A tsunami will do this sooner than a normal wave with a huge amount of energy to continue moving across the land rather than just up a beach.

I'll try and get some links and images up later. But I am waiting till I can see if we have any data for that part of the world which may include it. If you have any questions let me know :^)

Here is a good link

http://news.bbc.co.uk/1/hi/world/asia-pacific/4136289.stm