Extending the database of pre-computed tsunami simulations for the Indonesian tsunami early warning system (InaTEWS)
The ultimate goal of establishing InaTEWS is to reduce as much as possible the victims due to tsunami. Since 2008, InaTEWS has been operated by BMKG and has shown its performance, proven by its ability to reliably detect and analyze earthquakes within 5 minutes, produce early warnings, and disseminate the products promptly. One of the important elements in the tsunami early warning is the availability of a pre-calculated tsunami database. The tsunami database provides the information about estimated tsunami arrival times and heights in the affected area. In InaTEWS, the pre-calculated tsunami database is integrated into a decision support system that helps operators to take decisions in issuing tsunami warnings. In 2012, this system has been equipped with a database of tsunami simulations covering the Sunda Zone. Obviously this coverage is not sufficient to account for the Eastern part of Indonesia that is also prone to tsunami. As a result that stage of the tsunami result needs to be extended. A project involving BMKG, Alfred Wegener Institute (AWI) and DMInnovation started in May 2015 to strengthen the decision support system of InaTEWS. Several workshops at BMKG were carried out to expand the scenario database in eastern Indonesia. The basis for tsunami scenario computations is the unstructured mesh finite-element numerical model TsunAWI developed by AWI. It is based on non-linier shallow water theory. The discretization scheme is based on finite elements with the mesh generation (covering the whole Indonesian region) that allows for an accurate local resolution along the coast while keeping coarse resolution in the deep ocean. The discretization of faults as a source for tsunami model was developed by Geoscience Australia / DMInnovation. The tsunami scenarios have been calculated for 13 additional source zones, on total 11949 scenarios in eastern Indonesia. The data products of all these scenarios are integrated to the decision support system TOAST developed by gempa GmbH via the Scenario Database Interface TsunDaBI. The sensitivity of the scenarios database with respect to the epicenter density and magnitude variation needed to be assessed, to test as to whether the current tsunami database is already sufficient or additional simulations are needed. In total the scenario repository was extended from 4580 to more than 16000 simulations. The extended tsunami database is expected to improve the tsunami warning bulletin in East Indonesia considerably.
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