Tsunami struck Sri Lankan shores on Boxing Day

by Justice P. H. K. Kulatilaka

The word 'Tsunami' sounds musical, soothing and sweet. Albeit, to us the Sri Lankans it sounds eerie, is hurting and sore. It struck quite unawares bringing nothing but death. Tsunami is a Japanese coinage meaning harbour wave. It was unknown to the Sri Lankans. The Mahavamsa refers to a sea flooding of the coastal strip in the Kingdom of Kalyani, an act of vengeance by the sea gods because the king had caused a pious Bhikkhu monk to be slain and thrown into the sea. Perhaps tsunami was the biggest natural disaster known to Sri Lanka in its recorded history. Such human agony was unheard of.

Tsunami devastated more than two thirds of the coast where 25 percent of the island's population and 90 percent of the fishing community lived. According to the statistics supplied by the Ministry of Women Empowerment and Social Welfare, tsunami left in its wake 31,229 people dead, 4,093 missing and 22,536 injured.

More than 432,535 people had been displaced, 62,402 houses had been completely destroyed and 40993 partially destroyed. Ninety-six tsunami camps were set up to accommodate displaced people. The giant wave destroyed coasts, beaches and coral reefs which were considered as most beautiful and scenic in the world. On the whole the country was not prepared to face such a national calamity especially at a time when the country was grappling with the bloody war against ruthless terrorism.

Collision

According to the empirical scientific studies carried out by geoscientists and seismologists the tsunami of December 26, 2004 was caused by a collision of two of the earth's tectonic plates causing one plate to sink below the other. Collision of the Indian plate and Myanmar plate where by the Myanmar plate moved 15 feet over the Indian plate. This caused a rupture of more than 1200 km and width of over 100 km. The focus was at a depth of about 10 km from the earth surface. The epicentre of the earthquake was on the sea bed off the west coast to the south east of Banda Ache in Northern Sumatra. The earthquake recoded a magnitude of 9.3 Richter scale. The magnitude was such that it has caused the planet to spin 3 micro seconds or a million of a second faster and tilt about an inch on its axis [ NASA Geophysicists Jet Propulsion Laboratory in California].

The large and instantaneous displacement of sea floor leading to displacement of thousands of cubic kilometres of ocean water triggered off the massive ocean wave tsunami of the Boxing Day. The latter travelled a distance of 1500 km. and took two hours to reach the coast of Sri Lanka.

Where the trough of the waves [negative waves] reached the coast first it caused a phenomena called 'drawdown' which was soon followed by a 'run up' that brought massive block of water. Television showed to the viewers scenes of people happily collecting fish quite unaware of the killer wave that was to follow.

Identification

Mechanism to identify tsunamis is a complicated one. It comprises broad band seismic station, tide gauges, pressure sensors placed at the sea bottom, buoys placed on the sea surface and satellite connections.

At that point of time scientific studies relating to tsunamis had been confined to the Pacific Ocean region because Pacific Nations were the most affected and vulnerable region to the Tsunami threat. Pacific Tsunami Warning Centre has been located at Honolulu and connected to United States Geological Survey Mines Bureau in California and Japan Meteorogical Agency [evidence of Dr Weinstein at the video conference].

When tsunami hit the shores of Sri Lanka we did not have any mechanism to get an early warning of an incoming tsunami a killer wave. Neither did we have any link with the Pacific Tsunami Warning Centre nor the Japanese Meteorological Agency.

Dr. Weinstein told the Commission at the video conference that the Centre at Honolulu did not have any telephone or E- mail numbers to pass on the warning to Sri Lanka. In fact the traditional belief was that Sri Lanka was a safe area.

Tsunami waves

According to the Eastern Naval Command it was around 9 am. It observed water level in the Trincomalee harbour going up. It was an unusual phenomenon.

But there were no giant waves. It would have been due to the bathymetry of the coastline. Point Pedro was hit around 9.55 and KKS at about 10.30 am. When information was received from Nilaveli Navel Camp it was 9.45 am. By 9.20 Kirinda and Galle were hit. That point of time Navy did not have 'the knowledge, time or the mechanism to inform the public in advance. Besides, the Navy was struggling to save its own men and property at the naval bases'.

Average heights of tsunami wave in the Eastern coasts were 5 metres. Certain places waves rose up to a height of 7.5 metres.

In the Southern coasts average height had been five metres but in Kirinda and Yala and Megalle the giant wave had reached heights of 10 to 12 metres. Expert evidence to this effect came before the Tsunami Commission from Dr. Janaka J. Wijetunga. Dept. of Engineering, University of Peradeniya. The water line at the beach travelled several hundred meters inland as a wall of water with great destructive power inundating low lying coastal areas causing considerable loss of life and property.

To be continued