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

西苏门答腊明打威斑块的海啸历史和浊积古地震学

• 批准号: 421566368
• 负责人: Dr. Philipp Kempf
• 金额: --
• 依托单位: Fachrichtung Tektonik und Sedimentäre Geologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/421566368?language=en
• 关键词: Tsunami; history; turbidite; paleoseismology; Mentawai

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.

如果苏门答腊岛近海明打威群岛的地震空隙完全破裂，将导致8.7-9.0级地震，极有可能引发一场极具破坏性的海啸，威胁到沿海社区，包括拥有100万居民的巴东市。然而，在巴登北部和南部沉积物丰富的苏门答腊岛西海岸没有已知的海啸沉积，当地对以前的海啸淹没知之甚少。这项拟议的研究项目包括两个主要工作包。首先，我们将利用现有的近海地球物理数据和沉积岩芯来测试基于浊积岩的古地震学是否可以成功地应用于苏门答腊岛西部近海的海前弧前明打威盆地。这一部分依赖于以前获得的地球物理数据和现有的沉积物岩心。明打威盆地的沉积环境以前从未进行过浊积岩古地震学测试。这一结果极有可能揭示千年尺度的地震震动记录。其次，近海浊流古地震学研究将与陆上海啸沉积分析相结合。这项研究将依赖于一套从沿海沉积物中获得的约10米长的锤子岩芯，这些岩芯是在广泛的野外工作中获得的。这些岩芯将被用来揭示Sunda Arc俯冲带的地震活动(来自历史记录、已建立的珊瑚档案和我们新的浊流古地震记录)与苏门答腊岛中部西海岸海啸危险之间的关系。揭示巴东地区的海啸历史对于这个几代人都没有遭受过大海啸袭击的沿海社区至关重要--与2004年印度洋巨型海啸之前的亚齐地区沿海社区非常相似。该项目的创新之处在于：1)测试了成功应用浊流古地震学的弧前盆地环境；2)调查了明打威斑块沿岸的沉积古海啸记录；3)将陆上和近海记录结合在一起；4)将前者与其他古地震记录进行了综合，例如明打威群岛珊瑚的同震变形记录。这一创新方法将对俯冲带上的地震活动、海洋环境中的重力流、同震海岸变形和海啸地质灾害潜力之间的关系产生重要的见解。