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Jörn Behrens
Alfred Wegener Institute for Polar and Marine Research
Bremerhaven, Germany

Thursday, September 25, 2008
Foothills Laboratory 2, Room 1001
Lecture 11:00am

Accurate and Fast Near-Field Tsunami Detection by Means of Multi-sensor Analysis in the GITEWS Tsunami Early Warning System for the Indian Ocean

High sensitivity of the on-shore effects of tsunamis to the exact source mechanisms in the near field (e.g. in Sumatra, Java or Bali, Indonesia) demands for new techniques in real-time hazard assessment for early warning and mitigation systems. A new multi-sensor approach, involving seismic parameters, GPS dislocation vectors, and wave gauge measurements, allows for accurate assessment of the potential hazard within short time after the earthquake. This approach is based on a large number of pre-computed tsunami scenarios, indexed and stored in a geo-database for quick comparison to incoming measurements.
The scenario computations are preformed with a combination of a novel source term model, implemented in a software called RuptGen. RuptGen employs 2250 micro plates which are individually lifted to generate the bottom uplift for earthquakes with moment magnitudes between 7 and 9.
The hydraulic (wave propagation and inundation) simulations are carried out with a tsunami model called TsunAWI. This is an unstructured mesh finite element numerical model, based on the non-linear shallow water equations with Coriolis, internal viscosity and bottom frictional forced. The unstructured mesh technique allows for high resolution in coastal areas (approx. 100m) while maintaining computational efficiency with coarse resolution in the interior ocean (approx. 5-10 km).
The seminar will introduce the methodological background of the simulation tools. After showing tsunami sensitivity analysis in the near-field, the multi-sensor approach to tsunami hazard assessment is demonstrated. Finally, its application in context of the GITEWS tsunami early warning system is explained.
GITEWS: German-Indonesian Tsunami Early Warning System