Tsunami history and turbidite paleoseismology of the Mentawai Patch, west Sumatra

• Applicant: Dr. Philipp Kempf
• Subject Area: Palaeontology
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 421566368

A full-release rupture of the seismic gap on the Mentawai Patch offshore Sumatra would result in an M 8.7–9.0 earthquake, which would most likely induce a highly destructive tsunami threatening coastal communities, including the city of Padang with >1 million inhabitants. However, there are no known tsunami deposits along the sediment-rich Sumatran west coast north and south of Padng, and local knowledge about previous tsunami inundations is sparse.This proposed research project consists of two main work packages. First, we will use existing offshore geophysical data and sediment cores to test whether turbidite-based paleoseismology can be successfully applied in the marine forearc Mentawai Basin offshore west Sumatra. This part relies on previously obtained geophysical data and existing sediment cores. The sedimentary environment of the Mentawai Basin has never been tested before for turbidite-based paleoseismology. The results hold a strong potential to reveal a millennial-scale record of earthquake shaking. Second, the offshore turbidite paleoseismology study will be coupled with the analysis of onshore tsunami deposits. This research will rely on a set of ~10m long hammer cores from coastal sediments acquired during an extensive fieldwork campaign. These cores will be used to reveal the relationship between seismic activity of the Sunda Arc subduction zone (from historical records, established coral archives and our novel turbidite paleoseismological record) and tsunami hazard along the central Sumatran west coast. Revealing the tsunami history of the region around Padang is of utmost importance to this coastal community that has not been hit by a large tsunami in generations – quite similar to the coastal communities of the Aceh region before the giant Indian Ocean tsunami of 2004.The innovation of this project entails i) the test of a forearc-basin setting for the successful application of turbidite paleoseismology, ii) the investigation of sedimentary paleotsunami records along the coast of the Mentawai Patch, iii) the integration of onshore and offshore records, and iv) the synthesis of all the former with other paleoseismological records, e.g. co-seismic deformation records of corals along the Mentawai Islands. This innovative approach will yield important insights into the relationships between seismic activity along a subduction zone, gravity flows in the marine environment, co-seismic coastal deformation and tsunami geohazard potential.

• DFG Programme: Research Grants