November 14, 2008 A new tsunami warning system called the German Indonesian Tsunami Early Warning System (GITEWS) has just been implemented in Indonesia. Unlike previous tsunami warning systems, it uses new scientific procedures and technologies which are more suited to the specific geological conditions of the region.

More than 90% of tsunamis start as a result of earthquakes. The devastation a tsunami can wreak was seen in December 2004, when after a massive earthquake the province of Banda Aceh was decimated by a tsunami and approximately a quarter million people lost their lives. Earthquakes off the coast of Indonesia occur along a subduction zone, called the Sunda Arc, which extends from the north western corner of Sumatra to Flores in the east of Indonesia. If a tsunami occurs, the waves would only take 20 minutes to reach the shore which leaves very little time to warn of the impending risk.

Using a seismological network with over 120 stations throughout Indonesia, the GITEWS' evaluation software programme called SeisComP3 can determine the location and the magnitude of an earthquake within minutes. As not all earthquakes result in a tsunami, underwater measuring units send data to a buoy on the surface of the water and this data is passed on to the central warning center. GPS antenna on the buoys are used to determine irregular sea levels and motion while innovative measuring and filter procedures allow normal sea motion information to be suppressed. Computer simulations are used to pre-calculate the risk factors of possible tsunamis, taking into account information on population, infrastructure, wave heights and arrival times. This ensures that in the case of an emergency the pre-computed scenario will assist in the depiction of the emergency situation.

The data and information flow into a Decision Support System (DSS) and the officer in charge determines whether a tsunami warning is to be issued. The system contains extensive data bases, geo-data, risk information and hazard maps and is unique in terms of its conception and complexity. Once the information has been analyzed various organizations are warned, including government authorities and action forces. If necessary, the public can be warned and evacuation procedures can begin.

As tsunamis can travel at the speed of a jet aircraft and can swell to waves of up to 30 meters (approx. 98.5 feet), it is essential that early detection occurs before the wave hits the mainland.

See GITEWS for more details.

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