The challenge of installing a tsunami early warning system in the vicinity of the Sunda Arc, Indonesia

Abstract

Indonesia is located along the most prominent active continental margin in the Indian Ocean, the so-called Sunda Arc and, therefore, is one of the most threatened regions of the world in terms of natural hazards such as earthquakes, volcanoes, and tsunamis. On 26 December 2004 the third largest earthquake ever instrumentally recorded (magnitude 9.3, Stein and Okal, 2005) occurred off-shore northern Sumatra and triggered a mega-tsunami affecting the whole Indian Ocean. Almost a quarter of a million people were killed, as the region was not prepared either in terms of early-warning or in terms of disaster response. <br><br> In order to be able to provide, in future, a fast and reliable warning procedure for the population, Germany, immediately after the catastrophe, offered during the UN World Conference on Disaster Reduction in Kobe, Hyogo/Japan in January 2005 technical support for the development and installation of a tsunami early warning system for the Indian Ocean in addition to assistance in capacity building in particular for local communities. This offer was accepted by Indonesia but also by other countries like Sri Lanka, the Maldives and some East-African countries. Anyhow the main focus of our activities has been carried out in Indonesia as the main source of tsunami threat for the entire Indian Ocean. Challenging for the technical concept of this warning system are the extremely short warning times for Indonesia, due to its vicinity to the Sunda Arc. For this reason the German Indonesian Tsunami Early Warning System (GITEWS) integrates different modern and new scientific monitoring technologies and analysis methods

Applicability of the Decision Matrix of North Eastern Atlantic, Mediterranean and connected seas Tsunami Warning System to the Italian tsunamis

“…A large number of scenarios is pre-calculated by means of suitable tsunami numerical models and archived, and one or some combination of these is selected and used for the forecast and to issue the alerts. This strategy was initially introduced by the JMA (Japan Meteorological Agency) that is responsible for the Japanese TWS and has been recently adopted in other countries such as Indonesia where a TWS has been set up after the 2004 Indian Ocean tsunami mainly in cooperation with Germany in the frame of the joint German-Indonesia project GITEWS (Rudloff et al, 2009;Lauterjung at al., 2010) and Australia where a TWS is operational since 2009 (Allen and Greenslade, 2010). The process of decision in this case is based on observations and on tsunami model results, but in certain circumstances, especially for non-distant tsunamis, it might be a much more complicated task for the TWS operator and might require specific systems of decision support (see Steinmetz, 2010, for the GITEWS system) based on sophisticated information and communication technology tools, that are a real challenge for today and future research (e.g., see the efforts made within the ongoing European project TRIDEC for the development of a general purpose platform for early warning, including tsunami applications -http://www.tridec-online.…”

The UNESCO-IOC framework – establishing an international early warning infrastructure in the Indian Ocean region

“…This involvement of GITEWS in the ICG-IOTWS process has been extremely fruitful and an absolute necessary undertaking as the early warning system in Indonesia plays a crucial role for tsunami early warning in the Indian Ocean. Due to the geotectonic situation most of the tsunamigenic earthquakes threatening the Indian Ocean are generated along the Sunda Arc, an active continental margin running along the coastline of Indonesia (Lauterjung et al, 2010). The early warning system in Indonesia is able to deliver very first and fast indications and data with respect to a tsunami and, therefore, contributes to an ocean wide communication and information network for regional tsunami warning.…”

Real-time earthquake monitoring for tsunami warning in the Indian Ocean and beyond

“…Other sensor data such as buoy and tide gauge data will usually not be available within such a short time frame but will be needed later-on to either validate a warning status or to cancel it. Indian Ocean wide tsunamis will primarily be generated from large Sunda trench earthquakes (Lauterjung et al, 2010). A second potential source zone for tsunamogenic thrust events is the Makran trench, but due to the limited source dimensions it will potentially create local or regional tsunamis.…”