GEOFON and the Indian Ocean Tsunami Warning System

After the Mw=9.3 Sumatra earthquake of December 26, 2004, which generated a tsunami that effected the entire Indian Ocean region and caused approximately 230,000 fatalities, the German government funded the so- called German Indian Ocean Tsunami Early Warning System (GITEWS) Project. The GEOFON group of GFZ Potsdam was selected to develop and implement its seismological component. In this presentation we describe the concept of the Earthquake Monitoring System and report on its present status.The major challenge for a Earthquake Monitoring System (EMS) within a tsunami warning system is to deliver information about location, size, source parameters and possibly rupture process as early as possible before the potential tsunami hits the neighboring coastal areas. Tsunamigenic earthquakes are expected to occur in subduction zones close to coast lines. This is particularly true for the Sunda trench off-shore Indonesia, but also in the Macran subduction zone off- shore Iran. Key for an Indian Ocean monitoring system with short warning times is therefore a dense real-time seismic network in Indonesia, supplemented by a substantial number of stations in other countries and territories within and around the Indian Ocean. Up to 40 new broadband and strong motion stations will be installed until 2010 with real-time data collection using a private VSAT communication system.The GITEWS EMS Control Center in Jakarta will be based on an enhanced version of the widely used SeisComP software and the GEOFON earthquake information system prototype presently operated at the GFZ-Potsdam (http://geofon.gfz- potsdam.de/db/eqinfo.php). However, the Control Center software under development (SeisComP3) will be more reliable, faster and automatic but with operator supervison. It will use sophisticated visualisation tools, offer the posibility for manual correction and re-calculation, flexible configuration and support for distributed processing. Its large redundancy for algorithms, moduls and hardware assures easy integration into larger multi-sensor, multi- hazard control centers and decision support systems. A first prototype of the EMS Control Center software is already operational.