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Abstract

Two recent tsunamis in late 2018, in Sulawesi and Anak Krakatau, Indonesia, strikingly demonstrated the high vulnerability of communities to tsunamis induced by landslides and volcanic mechanisms. Both tsunamis were the result of a chain (cascade) of events: on 28 September in Palu, on the island of Sulawesi, the cascade consisted of a sequence of earthquake - landslide - tsunami, while on 22 December, after a prolonged period of volcanic activity, a flank failure occurred on Anak Krakatau, which in turn triggered a tsunami (Walter et al, 2019). In both cases, the resulting tsunamis caught the local population largely unprepared and caused a high number of fatalities. This has been attributed to the limited understanding of tsunami generation from mechanisms other than fault rupture and the lack of an effective tsunami warning system for non-seismic events. Both events have raised questions in the Indonesian society and among the relevant authorities about appropriate strategies for improved preparedness, early warning and mitigation for such events. The German-Indonesian project "TsunamiRisk" aims to help answer these questions through applied geoscientific and social science research aimed at developing policy recommendations and enabling transfer into practice. The perspective of local communities must be given special consideration, as it is ultimately they who are confronted with the direct impacts of such events on the one hand and who must implement better preparation and long-term mitigation on the ground on the other. Therefore, the project investigates the specific framework conditions as well as existing experiences in Indonesian communities with previous earthquake/tsunami events in order to support the discussion about adequate strategies and approaches for preparedness, early warning and mitigation of non-seismic tsunami hazards at the local level. The starting point for all this is to have a better understanding of the tsunami threats that communities face. The present study is intended to make a contribution to this.