New recording system to detect approaching tsunamis

November 20th, 2007 - 1:29 pm ICT by admin  

Washington, Nov 20 (ANI): Scientists have developed a new seafloor pressure recording system to detect tsunamis shortly after their development in the open ocean.
Developed by scientists at the Alfred Wegener Institute for Polar and Marine Research in Germany, the recording system known as PACT (Pressure-based acoustically coupled tsunami detector) would be used for the real-time detection of sea level rises in the deep ocean.
The primary objective of PACT consists of the new development of a reliable, compact and highly energy efficient system which will record and analyze seafloor pressure every 15 seconds, and which will transmit the information to the surface modem if a tsunami event is detected.
The German tsunami early warning system is unique in that it processes a multitude of information as the basis for a comprehensive and accurate evaluation of every particular situation.
Within just few minutes, measurements of the vibrations and horizontal seafloor movements off the coast of Indonesia provide a clear picture of the location and intensity of a seaquake, which, at the warning centre, facilitate the appropriate selection of a previously calculated tsunami propagation model.
However, not every seafloor quake causes a tsunami.
“There is only one way to be clear about this and avoid nerve-wrecking and costly false alarms: we must measure sea level directly”, says PACT-project leader Dr Olaf Boebel of the Alfred Wegener Institute.
For this purpose, sea level recordings must take place off the coast, in the deep ocean.
At water depths of thousands of meters, a tsunami wave travels at several hundred km/hr, but is only some tens of centimetres high, and approximately one hundred kilometres long. Not before it reaches the coast or shallower waters, does a tsunami wave develop into a massive wall of water several meters high.
Being able to detect the very slight sea level rise in the deep ocean reliably and precisely requires the use of bottom pressure sensors. These instruments are installed on the seafloor where they measure any sea level changes in the water column above.
In this process, the weight of any additional water leads to minute pressure increases at the seafloor which are, nevertheless, reliably recorded by the PACT bottom units.
The PACT system was successfully tested off the Canary Islands earlier this month, thus setting a new milestone for the development of the Indian Ocean Tsunami Early Warning System. (ANI)

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