Wave Warnings
November 11, 2008
Indonesian President Susilo Bambang Yudhoyono will attend Tuesday's ceremony in Jakarta along with representatives of the German government, the German Research Center for Geosciences (GFZ) said.
The German government financed the 45-million-euro ($58 million) project, known as the German-Indonesian Tsunami Early Warning System, or GITEWS.
The devastating tsunami four years ago was triggered by an earthquake that measured 9.3 on the Richter scale off the coast of the Indonesian island of Sumatra. The GFZ said the death toll would have been considerably lower if an early warning system had been in place at the time.
Avoiding the worst
The system about to be launched makes use of sensors placed on the seabed which relay details of changes in water pressure to buoys on the surface. The information is then transmitted via satellite to a tsunami early-warning center in Indonesia.
The German government proposed developing an early-warning system shortly in cooperation with Indonesia after the disaster struck.
The backbone of the system is ten large yellow steel buoys which monitor the water and seabed and flash news of changes to authorities.
"Were a tsunami to cross a sensor then the pressure would change," said Joern Lauterjung, project coordinator at the GFZ. "This pressure can be measured very exactly."
Reacting fast
The new system also boasts 20 stations where sea levels can be measured, using some 100 seismometers and global positioning system satellites to detect tremors. Collected data is sent to a headquarters, where experts have to be ready to make instant decisions based on the information they receive. The tsunami warnings have to be issued preferably within five minutes. They will be based on rapidly determined earthquake parameters and pre-calculated tsunami scenarios.
"The central question is knowing how to interpret the data so that we can say with complete certainty that a tsunami is coming or not -- and predicting what effect it will have," said Stefan Dech, director of the German Aerospace Center in Oberpfaffenhofen and head of the "Early Warning and Situation Center, Risk Modeling and Earth Observation" project team. "Our experts have at most ten minutes to reach conclusions and issue a warning."
"If our predictions are correct 50 percent of the time then we could say the system was successful," he went on. "Other tsunami early-warning systems such as those that exist in the Pacific regularly issue false alarms."
Educating the public
The GITEWS projects can already point to one success -- the Bengkulu earthquake off Sumatra on Sept. 12, 2007, when it was possible to obtain a first "heads-up" alert after less than two minutes and a first estimate of location, depth range and magnitude after two-and-a-half minutes.
"The Indonesian meteorological and geophysical services were able to issue a warning 15 to 20 minutes before the wave hit," said Lauterjung.
All the buoys should be installed by early 2009, and the German team will remain in Indonesia another year to help train local staff.
"I believe we need to work on the system with our Indonesian counterparts for another few years and to continue training," said Lauterjung. "This is a very long-term project. Our Indonesian partners also have to educate the population in terms of how they should react to a warning, and this is a huge task."