Tsunami Early Warning System takes important step forward
22 Novembre 2007
Researchers working on the German-Indonesian Tsunami Early Warning System (GITEWS) have successfully tested a new method that is intended to ensure the reliable communication of data from
detectors on the seafloor to the warning centre.
In order to solve the problem of data transfer – one of the greatest challenges, according to the Alfred Wegner Institute for Polar and Marine Research (in charge of this part of the GITEWS
project) – scientists installed an acoustic modem in the bottom unit of the system. This modem uses a sequence of sounds to transmit information to a second modem connected to a buoy near the
surface. This in turn sends the information via satellite on to the warning centre.
The units installed on the seafloor are bottom pressure sensors that measure changes in sea level off the coast in the deep ocean in real-time. As the tsunami – still hardly recognisable as
such – rolls over the pressure sensors, the additional water leads to a slight increase in pressure on the seafloor, an increase that the sensors record. ‘This is the only one way to be clear
about tsunamis and avoid nerve-wrecking and costly false alarms,’ says Dr Olaf Boebel of the Alfred Wegner Institute, project leader of the team developing the so-called pressure-based
acoustically coupled tsunami detectors (PACT).
In the deep ocean with depths of thousands of metres, the change in sea level brought about by a tsunami will not exceed some tens of centimetres. It is not before it reaches shallower waters
that the killer wave develops into a massive wall of water that will be several metres in height.
After the successful completion of the tests, which were conducted in a trial set up just north of the Canary Islands, the new transmission method will now be integrated in GITEWS. As a next
step, further tests ensuring the system’s reliability under more extreme weather conditions are scheduled for early next year in the Mediterranean. ‘Surely, the upcoming winter storms will give
us the opportunity to discover the limits of the system,’ Dr Boebel predicts.
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