Organic-geochemical proxy for tracing recent and historical Tsunamis in time and space

日本的沉积档案保存了千年前的海啸沉积物，超出了人类的记录。仅自有仪器记录以来，当地地震就记录了300多次大大小小的海啸。在更远的地方，数百块这样的石碑竖立在日本海岸线上，其中一些可以追溯到1150多年前公元869年的乔根海啸之后。对于研究历史，尤其是从沉积记录中识别古海啸沉积，有机化合物基于其保存潜力显示出巨大的潜力。事实证明，这种有机地球化学标记物是调查现代海啸沉积物和探测那些肉眼无法识别的沉积物的宝贵工具。但基于高保存潜力和具有高物源特异性的指示性化合物群，有机标志也对历史和古海啸研究做出了重大贡献。因此，这项研究的目的是建立适当和可靠的自然有机指标，结合标准参数(粒度、XRF、微古生物、测年)，以多代理方法原则上识别沉积档案中的历史和古海啸。更广泛地说，通过这项研究，我们进一步致力于将研究领域的跨学科领域(即海啸研究、有机地球化学和沉积学/微古生物学方法)与更全面地洞察发生在最后40%的洪水中的过程(例如，运输、沉积、海啸反冲分布)，因为它们位于明显可识别的沙质海啸沉积的界限之外，至今仍几乎未知。

Japanese sedimentary archives preserve millenarian tsunami deposits beyond human records. Since the beginning of instrumental records alone, over 300 tsunamis – large and small– have been documented from local earthquakes. Further on, hundreds of these stone tablets erect along the Japanese coastline, some dating back to more than 1150 years ago in the wake of the 869 CE Jogan tsunami. For the investigation of historic-, but especially to identify paleo-tsunami deposits from the sedimentary record, organic compounds show great potential based on their preservation potential. Such organic geochemical markers have been proven a valuable tool to investigate modern tsunami deposits and to detect those deposits beyond the limit of visual recognition. But based on high preservation potentials and indicative compound groups with high source specificities organic markers contribute also significantly to historical and paleo-tsunami research. Consequently, the aim of this study is the establishment of appropriate and reliable natural organic indicators combined with standard parameters (grain size, XRF, micropaleontology, dating) in a multi-proxy approach to identify historic- and paleo-tsunamis in sedimentary archives in principal. More generally, through this study, we further aim to combine interdisciplinary fields of research areas (i.e., tsunami research, organic geochemistry, and sedimentological/micropaleontological approaches) with the intention to gain a more holistic insight into processes (e.g., transport, deposition, tsunami backwash distribution) that occur in the last 40% of the inundation, which remain today virtually unknown, as they lay beyond the limit of visibly recognizable sandy tsunami deposits.