Asian Quake Was Colossal, Say British Scientists
By Scottish Press Association Reporters
Mon 27 Dec 2004
The colossal scale of the earthquake which devastated much of southern Asia was today indicated by new calculations from British scientists.
It was more powerful that all the world’s earthquakes of the past five years put together, scientists said.
It is now also known that the earthquake had three distinct phases, each only a matter of seconds apart, said Dr Roger Musson, a seismologist at the British Geological Survey in Edinburgh.
He said the quake took place along a 750-mile line where two giant tectonic plates, the Indian plate and the Eurasian plate, came together – the Indian plate dipping below and overlapping with the Eurasian plane.
The quake took place in three phases, starting in the south and moving north, as the two plates came closer together by 60 feet.
“We know have some more information and there were three events merged together,” said Dr Musson, “The first was off the coast of northern Sumatra, and this was the smallest break.
“That brought down the next section along to the north, at about the Nicobar islands, and then the Andaman islands.
“The total length of this is 750 miles, which is really massive,” said Dr Musson.
“The Indian plate is continually moving to the north the whole time, at the rate of several inches a year.
“Because it is colliding with something else, it can’t continue to move smoothly so the force builds up and up.
And he said: “If you take the energy from all the earthquakes in the world over the past five years, it would be less than what was released in one go yesterday morning.
“It really is something incredibly big.”
Earlier, another British Geological Survey expert Dr David Booth told how the quake generated the tsunami.
“Not all earthquakes will do this,” he said.
“First of all the earthquake has got to curve underwater in the ground under the ocean and also the movement of the rock has got to reach the surface.
“Where there is a displacement of the ocean floor it causes a movement on the surface and it spreads out from there at a speed of about 300 miles an hour.
“It’s fast, but slow enough for warning to be given, if a sophisticated warning system is set up.”
Dr Booth said he was aware of a warning system in the Pacific but that he was not aware of a warning system being set up around the Indian Ocean where the colossal earthquake was born.
“This wave may only be a few feet high in the ocean but as it reaches shallow water the wave builds up very quickly in height and these waves can reportedly be 170 feet high.”
He said there had been “one or two” small tidal waves this year, but “nothing like the scale” of the Asia one.
He went on: “It is a long, long time since there has been anything quite as devastating.”
Dr Booth explained: “The ocean floor is being pushed under the continent and enormous stresses build up and because the length of the fault is very long you have the potential for a very large earthquake as the whole fault moves as one.”
Just after 1am yesterday vibrations were picked up by instruments in the UK – about 5,000 miles away.
“Our instruments have recorded the tremor here. In fact this is the largest we have seen with regards to displacement in instruments.
“The waves generated from the tsunami would have travelled all around the world.”
This article is from: Scotsman.com News
See also: Tsunami horror hits home