by Kathy Poh
The way the oceans took all that they had was how a predator might pounce on its unsuspecting prey. As waters along the Phuket coastline receded, exposing rock pools and floundering fish, tourists and locals alike flocked to marvel at this curious phenomenon. A natural disaster was probably the last thing on their minds, especially on the day after Christmas. By the time mountainous waves loomed over the horizon, it was already too late to run.
With five million people affected, 230,000 lives taken and 1.7 million people displaced, the tsunami that ravaged coastlines of the Indian Ocean in 2004 is the deadliest in recorded history. Today, it might be hard to comprehend how warning signs of an earthquake and receding seas were ignored, but tsunamis have been historically more common within the Pacific Ocean rather than the Indian Ocean because of the conditions under which they occur.
Arising from a sudden displacement of water, they are triggered by undersea megathrust earthquakes wherein there is vertical tectonic movement; this occurs at convergent plate tectonic boundaries where
one plate is subducted under another. While tectonic earthquakes are frequent in Indonesia, such earthquakes are rare. In the case of the 2004 tsunami, whose epicentre lies off the western Sumatran coast, a rupture along boundaries of the Indian Plate and the overriding Burma Plate caused a 9.1-magnitude earthquake and displaced massive amounts of water that travelled at speeds over 800 km/h.
The sheer amount of energy released – 23,000 times what was contained in the atomic bomb detonated over Hiroshima – resulted in damage to countries as far-flung as South Africa.