The Tsunami Disaster
At 0059 GMT on 26 December 2004, a magnitude 9.3 earthquake ripped
apart the seafloor off the coast of northwest Sumatra.
Over 100 years of accumulated stress was released in the second
biggest earthquake in recorded history.
It unleashed a devastating tsunami that travelled thousands of
kilometres across the Indian Ocean, taking the lives of nearly 300,000
people in countries as far apart as Indonesia, the Maldives, Sri Lanka
Two hundred and forty kilometres (150 miles) off the coast of Sumatra,
deep under the ocean floor, at the boundary between two of the world's
tectonic plates, lay a 1,200km (745 miles) trench called the
Andaman-Sumatran subduction zone.
At about the same speed as your fingernails grow, the lower plate,
carrying India, is being forced or subducted beneath the upper plate,
carrying most of South-East Asia, dragging it down, causing huge
stresses to build up.
These stresses were released on 26 December. Shaking from this giant
mega-thrust earthquake woke people from sleep as far away as Thailand
and the Maldives.
Unlike the more frequent strike-slip earthquakes of Kobe or Los
Angeles, which last for a matter of seconds, subduction zone quakes
last for several minutes.
The shaking during the Indonesian event went on for eight minutes.
Nobody knows how many died in the actual quake itself, but scientists
have since visited the nearby island of Simueleu and found something
The whole island has been tilted by the force of the earthquake,
causing coral, submerged beneath the ocean for thousands of years, to
be thrust out of the water on the east side; bays in the west have
"We were astonished to find ourselves walking through a pristine
marine ecosystem, missing only its multitude of colours, its fish, and
its water," said Professor Kerry Sieh, from the California Institute
of Technology, US.
Yet, when the shaking from the earthquake subsided, no-one had any
idea that the tremors had set in motion something far more deadly - a
Deep under the Indian Ocean, at the epicentre of the quake, the 20m
(65ft) upward thrust of the seafloor set in motion a series of
geological events that were to devastate the lives of millions.
Billions of tonnes of seawater, forced upward by the movement of the
seabed now flowed away from the fault in a series of giant waves.
The only people in the world to have any idea what had happened were
thousands of kilometres away on the island of Hawaii.
But, relying on seismic data alone, the scientists at the Pacific
Tsunami Warning Centre had no idea the earthquake had unleashed an
It was a full 50 minutes after they first picked up...