Sunday December 26th, 2004 seemed to be another sunny day on the island of Sumatra (Indonesia) and in the early morning only slowly the shores became frequented by tourists and locals. At 7:58:53 local time a strong earthquake was felt, lasting unusual long with 8-10 minutes it caused however minor damage. But the magnitude 9.1-9.3 earthquake had displaced an estimated 1.600 kilometres long segment of the seafloor by 15 metres. The water column above this segment was first pushed up and generated then a series of four waves travelling in opposite direction.
Video 1. The tsunami in the Indian Ocean is probably one most well documented disasters in modern history, the accounts and video footage helped to understand what happened in the various phases and how a tsunami propagates on land. ?Tsunami: Caugth on Camera? is a TV-documentary produced in 2009 almost exclusively with original footage (the video shows victims and injured people ? viewers discretion is advised).
Fifteen minutes after the earthquake, at 8:14 local time, the first wave reached the coast of Sumatra without a warning. In Thailand it was the trough of the wave to reach first the coast. Eyewitness accounts and video footage shows how the sea level first regress, large parts of the shores and even reefs emerge, then suddenly a huge and fast wall of water approaches. Video footage showed also how the first wave cleared the path for the later ones, that even faster and stronger hit the interior areas along the coasts.
The waves travelled for 8 hours trough the entire Indian Ocean, bringing destruction and death to the coasts of Indonesia, Thailand, Sri Lanka, India, Somalia, Kenya, Tanzania, Madagascar and flooding almost completely the smaller islands in the Indian Ocean.
The death toll rose in the following hours and days after the catastrophe ? more than 230.000 fatalities were counted, possibly thousands of bodies remain either lost to the sea or unidentified, even more people injured and large areas devastated.
Almost one year earlier, in the morning of December 26th, 2003, the 142.000 inhabitants counting city of Bam in the Iranian province of Kerman was hit by 12 seconds lasting magnitude 6.5 earthquake. Protecting and overlooking the city was the mighty citadel of Arg-e-Bam, build during the reign of the Safawida-dynasty in the years 1501-1736. The citadel was constructed in old times with bricks of clay and straw mortar. Many buildings in the modern city were still constructed with similar materials ? a typical house, often with many floors, had a heavy roof of concrete resting on walls of simple bricks. This type of construction, the main weight of the construction is situated high above the ground, free to shake and resting on a weak support, is very unstable even during a moderate earthquake. In seconds 80% of the buildings in Bam collapsed and many sleeping inhabitants were surprised inside their houses by the quake. More than 26.000 people died and 120.000 people lost their homes.
Bibliography:
BARBER, A.J.; CROW, M.J. & MILSOM, J.S. ed. (2005): Sumatra ? Geology, Resources and Tectonic Evolution. Geological Society Memoir No. 31: 304
BRYANT, E. (2008): Tsunami ? The Underrated Hazard. 2.nd edition Springer: 338
KOZAK, J. & CERMAK, V. (2010): The Illustrated History of Natural Disasters. Springer-Verlag: 203
MANAFPOUR, A.R. (2004): The Bam, Iran earthquake of 26 December 2003 ? Field Investigation Report. Halcrow-EEFIT Report: 59
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