The earthquake causing the tsunami in the Indian Ocean late last year has put extra stress on neighbouring fault lines, increasing the likelihood that future shocks triggering similar mega-waves will occur, recent European research in Nature calculated – a forecast that appears to have been borne out by the latest aftershock to hit Indonesia on 28 March.
The UK research team behind the study found that the quake – which measured 9.0 on the Richter Scale and shunted almost 250 000 square kilometres of the Indian plate on 26 December – has placed a great deal of stress on two fault zones: the Sunda trench and the Sumatra trench which run close to the devastated Indonesian province of Aceh.
|UN relief workers deliver tents to people made homeless by the tsunami in Sri Lanka|
© UNHCR Colombo
The most immediate threat is probably an earthquake of 7.5 on the Richter Scale somewhere in the province, predicted the seismologists, led by John McCloskey of Ulster University, Northern Ireland. This, they said before last week's event, could trigger another tsunami. The massive wave that swept across the Indian Ocean just before the New Year reached as far as the east coast of Africa. It killed an estimated 273 000 people in 11 Indian Ocean countries, with Indonesia, Sri Lanka and Thailand among the hardest hit countries.
Aceh has been hit by a number of smaller tremors – including one measuring 5.9 on 25 March and now an 8.7 tremor with its epicentre 56 miles south of the island of Simeulue – which experts say are aftershocks of the December quake. Last year's quake killed over 126 000 people and 93 000 are still missing in Indonesia alone. Some 2 000 are predicted to have been killed in the most recent quake.
Seeing the signs
“People think ‘well you've had your bad luck', but earthquakes cluster in time and in space,” McCloskey notes. This underlines the need for a tsunami early-warning system in the region. Following a powerful earthquake that shook southern Japan in March, the Japanese authorities said they would issue tsunami alerts for six Pacific nations, including Indonesia.
The Hawaii-based Pacific Tsunami Warning Centre currently gives information to Pacific-rim countries. However, the Indian Ocean remains largely uncovered by such a system. The international community has vowed to set one up and European research and know-how will undoubtedly contribute to this effort.
The EU is already closely involved in disaster research with, for example, contributions to the Global Monitoring for Environment and Security (GMES) initiative and activities carried out at the European Laboratory for Structural Assessment (ELSA) – part of the Institute for the Protection and Security of the Citizen, under the Commission's Joint Research Centre DG.
“Natural disasters cannot be entirely prevented – they are an integral part of our changing planet, shaping our landscapes since time immemorial,” notes the EU's Environment Research website. “[But] research has contributed to improving forecasting methods in order to provide early warnings for effective evacuation strategies, and risk assessment techniques for pre-disaster planning and mitigation,” it continues.
The UN, which is coordinating the international effort, hopes to have a high-tech tsunami warning system up and running by the end of 2006. If another devastating wave takes shape, scientists should be able to predict where, when and just how hard the water will hit, once the infrastructure is in place. After that, the main challenge will be how to get the warning out to poor communities which lack modern communications technologies, and even electricity, before the waves strike.
The latest earthquake to strike Indonesia flattened houses and cut power along the west coast as far as the beleaguered Aceh province. According to reports, it caused widespread panic across Indian Ocean countries still traumatised by the December 2004 quake and tsunami disaster.
EU sources, Nature and SciDev.net, CBS