Meanwhile tsunami early warning systems are in operation, to inform the residents about a tsunami threat in time. So it is possible to identify the danger and to initiate safeguarding.
The funktionality is explained by the example of the tsunami early-warning system in Indonesia, which was set up by the support of Germany. The German Research Centre for Geosciences was leading the technical devolopment and installation.
The geological situation in Indonesia with extremely short periods (30 to 40 minutes) between an earthquake and the arrival of a tsunami on the coast called for an entirely new approach to the design of tsunami early warning. The system is based on more than 300 different land-based sensor systems. The warning is based on very fast and precise recording and evaluation of earthquakes, which forms the core of the warning system. The rapid determination of earthquake parameters (location, depth, magnitude) via 160 seismometers on land is the first and most important foundation for a tsunami preview by means of modeling, as well as the generation of a warning message that is based on the preview. This first assessment of the situation is subsequently verified by GPS data from continuously GPS stations and tide gauges along the coast of Indonesia. The tsunami itself is detected by the tide gauges via pressure, radar- and floating sensors.
The development of the entire system was continuously supplemented with the latest research results. Using the seismological analysis system SeisComP3, it was therefore possible to develop a new, rapid and robust method for the determination of earthquake parameters, which is now used in virtually all countries bordering the Indian Ocean and other countries around the world (a total of approximately 40 nations use SeisComP3). Another completely new approach is the use of GPS measurements for the precise determination of the deformation of the earth crust, from which conclusions about the rupture mechanism and thus a possible tsunami formation can be recorded very quickly.
The innovative conceptual design of the system allows an evaluation of measurement data from all sensors in the shortest possible time so that a reliable tsunami warning may be released in less than five minutes. Consequently, an advance warning of about 30 minutes remains for the main Indonesian islands. The islands offshore Sumatra along the Sunda Trench are located in the immediate vicinity of the earthquake epicenters, a warning via the warning centre in Jakarta is not always possible here because of the very short time until the arrival of a tsunami. Here, above all provisions must be made through education and training of the population.
More information about the components and operation of the Indonesian tsunami early warning system under www.gitews.org.
After the severe earthquake on December 26th in 2004 a tsunami early warning system has been built up in Indonesia with the support of different Helmholtz Centres, coordinated by the GFZ. The movie shows the most important sensor systems and technological developments of the system. It is working since November 2008 and was oficially handed over to Indonesia in March 2011. (Movie: GFZ)
Text: Dr. Ute Münch, Dr. Jörn Lauterjung, Deutsches GeoForschungsZentrum (GFZ)