Joint Research between Indonesia and Germany on Volcanic and Landslide induced Tsunamis: Recommendations for the Way Ahead

Created by researchers of the Tsunami_Risk Project together with Ina2CORE Members Introduction In 2018, Indonesia was hit by two tsunamis that claimed hundreds of lives. Both tsunamis caught a largely unprepared population by surprise, in part because they were not detected by the existing seismic-based warning system that has been in place since 2008. What can be done to better prepare for non-seismic tsunamis in the future? The 2022 Global Platform for Disaster Risk Reduction mandates the use of global resources and emphasizes local contextualization. Warning at-risk populations is often considered the "last mile" of a top-down warning system approach, but it should be considered the "first mile". In line with this paradigm shift, research conducted by German-Indonesian teams over the years 2020-2024 has highlighted new methods for identifying and assessing potential non-seismic sources of tsunamis. In close cooperation with Indonesian authorities, the researchers used, among others, the well-documented cases of the 2018 Palu and Anak Krakatau tsunamis to identify underlying processes and propose solutions to improve preparedness and warning systems for cascading events in Indonesia and beyond. As the threats are mainly in the near field, response times are extremely short, typically in the range of 3 to 20 minutes. This requires a concerted effort by all stakeholders to strengthen self-protection capabilities at the community level, especially for self-evacuation, as well as a fast and reliable end-to-end warning process to enable a rapid response. Key findings and recommendations for policymakers are summarized. Additional information is provided in a technical supplement and a community-level supplement. Key findings 1. The various seismic and volcanic tsunami risks are highly regionalized. | Earthquake-induced tsunami hazard is widespread along the Sunda Arc, a major plate boundary in the Indian Ocean, and along the complex microplate boundaries in central and eastern Indonesia. Volcanic-induced tsunami hazard is concentrated mainly in central and eastern Indonesia, with the exception of Anak Krakatau [1]. Submarine and coastal landslides and volcanic eruptions can generate tsunamis [2], so priority should be given to densely populated coastal areas close to these hazard zones. Coastal areas near seismically active zones, river deltas, and areas of future land reclamation projects should also be prioritized. In addition, coastal communities are soci