Dating tsunami deposits: Present knowledge and challenges
Dating tsunami deposits: Present knowledge and challenges
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DOI：
10.1016/j.earscirev.2019.102971
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发表时间：
2020
影响因子：
12.1
通讯作者：
T. Ishizawa;K. Goto;Y. Yokoyama;J. Goff
中科院分区：
文献类型：
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作者：
T. Ishizawa;K. Goto;Y. Yokoyama;J. Goff
细粒沉积物海啸沉积物的测年方法可分为两类：(1)直接使用海啸沉积物内部的材料测年；(2)间接使用海啸沉积物上下的材料测年。对于前者，光激发发光测年(OSL)有一个可能的优势，那就是可以直接测定海啸沉积的沉积物的埋藏年龄。然而，由于方法的限制，OSL测年并不总是提供可靠的年龄。尽管对海啸沉积物中重新加工的物质进行14C和U-Th测年是确定事件年龄的可能手段，但结果仅代表了沉积的最大年龄。出于这些原因，测年通常是从海啸沉积物上方和下方的样品中间接获得的~(14)C年代。然而，间接注明日期的结果并不提供事件的准确时间。因此，获得过去海啸的高精度测年的能力存在明显的局限性。最近的方法学发展，包括将贝叶斯统计分析应用于放射性碳测年结果和选择适当的测年材料，通过减少误差，大大提高了年龄确定的准确性。这篇综述介绍了几个改进的方法，这些改进加强了海啸沉积年龄的估计。对于更准确的海啸年龄估计来说，最重要的一点是14C样本的数量以及贝叶斯统计分析的使用。这些要点不仅适用于海啸沉积物，也适用于过去的许多其他地质灾害事件。
Dating approaches for fine sediment tsunami deposits can be divided into two categories: (1) dating directly using materials from within a tsunami deposit, and (2) dating indirectly using materials from above and below it. For the former, Optically Stimulated Luminescence (OSL) dating has a possible advantage in that is can directly date the burial age of sediments laid down by a tsunami. However, because of methodological limitations, OSL dating cannot always provide a reliable age. Although14C and U–Th dating of reworked material from within a tsunami deposit are possible means of determining the age of the event, the results merely represent a maximum age of deposition. For these reasons, dating is commonly achieved indirectly from14C dates taken from samples in sections immediately above and below a tsunami deposit. However, indirectly dated results do not provide a precise timing of the event. Therefore, there are distinct limitations in the ability to obtain high precision dating of past tsunamis.Recent methodological developments including the application of Bayesian statistical analysis to radiocarbon dating results and the selection of appropriate dating materials has significantly improved the accuracy of age determination by reducing errors. This review presents several methodological improvements that have enhanced tsunami deposit age estimation. The most important points for a more precise tsunami age estimation are the numbers of14C samples dated coupled with the use of Bayesian statistical analysis. These points are applicable not only to tsunami deposits but also to many other past geohazard events.