Sedimentological post-tsunami survey of the deposits formed by the September 16, 2015 Illapel tsunami in central Chile

对 2015 年 9 月 16 日智利中部伊拉佩尔海啸形成的沉积物进行海啸后沉积调查

基本信息

批准号：
310697700
负责人：
Professor Dr. Hans Heinrich Bahlburg
金额：
--
依托单位：
Institut für Geologie und Paläontologie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/310697700?language=en
关键词：
Sedimentological post tsunami survey deposits

项目摘要

On September 16, 2015 a Mw 8.3 earthquake off the coast of Illapel, central Chile, triggered a tsunami reaching wave heights exceeding 4.5 m at the town of Coquimbo. Eye witness reports indicate that the tsunami deposited sediments at several coastal sites including the coast near the village of Tongoy south of Coquimbo. Post-tsunami surveys conducted in the wake of a larger tsunami depositing sediment onshore are an indispensable tool in the study of tsunami deposits. They are instrumental not only in encompassing the large and still not completely explored variety of sediments deposited by tsunamis but also for gauging the difference between modern deposits and those contained in the paleotsunami record. Recent studies indicate that sediment thicknesses and extent, sedimentary structures, grain-size distributions and petrographical composition maybe significantly altered already in the first few years after deposition. These differences are largely due to post-depositional modification including early diagenesis. Presently there are only two studies exploring these changes by following the deposits fate in the years following a tsunami event. In the proposed study we will map the spatial distribution of the deposits laid down by the September 16, 2015, Illapel tsunami. Distance from the coast to the line of maximum inflow as well as the relationship between this distance and the landward end of sediment deposition are of particular interest. If present we will record markers of the inundation height. We will record the sedimentological features of the deposits by digging pits and trenches. We will sample the deposits in grids covering the lateral extent of the sediments to map the spatial arrangement of grain-size distributions. If more than one tsunami layer is present we will sample each layer, or, if possible, each lamina. We will also sample for later OSL studies to explore the reasons for inhomogenous bleaching of datable grains in tsunami deposits observed in several studies. Where possible we will interview eye witnesses to obtain information on inundation heights and other observations.

2015年9月16日，智利中部Illapel沿海地区的MW 8.3地震触发了海啸，达到了高奎姆镇超过4.5 m的海浪高度。目击者的报告表明，海啸将沉积物沉积在多个沿海地区，包括科奎伯以南的汤托伊村附近的沿海地区。在近海的海啸沉积沉积物后进行的海啸后调查是海啸沉积研究中必不可少的工具。它们不仅可以涵盖海啸沉积的大型沉积物，而且还没有完全探索的种类，而且还衡量了现代沉积物与古植物记录中的沉积物的差异。最近的研究表明，沉积物的厚度和程度，沉积结构，晶粒大小的分布和岩石学组成可能在沉积后的头几年已经发生了显着改变。这些差异在很大程度上是由于沉积后修饰，包括早期成岩作用。目前，在海啸事件发生后的几年中，只有两项研究探讨了这些变化，探索了这些变化。在拟议的研究中，我们将在2015年9月16日在Illapel海啸中绘制存款的空间分布。从海岸到最大流入线以及该距离与沉积物沉积的地面端之间的关系的距离特别感兴趣。如果存在，我们将记录淹没高度的标记。我们将通过挖洞和沟渠来记录沉积物的沉积学特征。我们将在覆盖沉积物侧面范围的网格中采样沉积物，以绘制晶粒大小分布的空间排列。如果存在多个海啸层，我们将采样每层，或者，如果可能的话，每个层。我们还将采样以后的OSL研究，以探讨在几项研究中观察到的海啸沉积物中数据谷物谷物的非构态漂白的原因。在可能的情况下，我们将采访目击者，以获取有关淹没高度和其他观察结果的信息。