The tsunami and cyclone hazard in Myanmar - Surveying coastal geoarchives for sedimentary evidence of extreme wave events

缅甸的海啸和气旋灾害 - 调查沿海地质档案以获取极端波浪事件的沉积证据

基本信息

批准号：
299338813
负责人：
Dr. Dominik Brill
金额：
--
依托单位：
Geographisches Institut
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/299338813?language=en
关键词：
tsunami cyclone hazard Myanmar Surveying

项目摘要

Since at least the 2004 Indian Ocean Tsunami (IOT) the benefits of geological tsunami evidence are well established. Although the IOT 2004 also had an exceptional magnitude, its catastrophic effects can only be explained by missing awareness concerning the tsunami risk of the region. Being the first tsunami of this dimension on instrumental and historical records, only geological evidence could have provided information on predecessor events to raise awareness and trigger vulnerability-reducing measures. This example and similar observations after tropical cyclone (TC) Nargis 2008 in Myanmar or Supertyphoon Haiyan 2013 in the Philippines demonstrate that robust hazard assessment must be based on the occurrence of extreme wave events (EWE) with different magnitudes over a prolonged time. While frequency-magnitude information from modern and historical TCs and tsunamis in SE Asia is restricted to a few centuries, geological imprints potentially cover periods of several millennia and record EWE with exceptional magnitudes and low frequencies.While the IOT 2004 triggered intensive research in most affected areas, still very little is known about EWE deposits in Myanmar. In consequence, the long-term hazard due to exceptional TCs and tsunamis is poorly constrained, although Myanmar is exposed to coastal flooding from three major sources: (i) eastward-moving TCs generated in the Bay of Bengal (e.g. TC Nargis); (ii) tsunamis triggered by complete ruptures of the North-Sumatra-Andaman segment of the Sunda Arc (e.g. the IOT 2004); and (iii) tsunamis triggered by ruptures of the Rakhine (Arakan) segment offshore western Myanmar (e.g. the 1762 tsunami). Since the lack of investigations is at least partly the result of a limited research activity due to the political isolation of Myanmar during the last decades, we assume that geological evidence of EWE is present in suitable near-shore geoarchives; these can contribute to an improved understanding of the long-term tsunami and cyclone hazard.While the preconditions for the proposed research are provided by a cooperation between Yangon and Cologne Universities, the possibility of poorly preserved or scarce EWE deposits advises a survey of several sites rather than a systematic investigation of individual locations. Therefore, 6-8 beach-ridge plains along the coasts of Myanmar shall be surveyed using light equipment for levelling (DGPS) and sampling (trenches, push cores) of EWE landforms (storm ridges, washover fans) and sand sheets. In combination with sedimentological (granulometry, fauna, mineralogy, geochemistry) and chronological (radiocarbon, optically stimulated luminescence) laboratory analyses the proposed survey shall trigger follow-up projects by (i) providing a basis for the systematic investigation of promising sites; and (ii) transferring knowledge to local graduates that participate in the field survey.

至少自 2004 年印度洋海啸 (IOT) 以来，地质海啸证据的益处已得到充分证实。尽管 2004 年的 IOT 规模也非常大，但其灾难性影响只能通过对该地区海啸风险的认识缺失来解释。作为仪器和历史记录中此类规模的第一次海啸，只有地质证据才能提供有关先前事件的信息，以提高认识并触发减少脆弱性的措施。这个例子以及 2008 年缅甸热带气旋 (TC) 纳尔吉斯或 2013 年菲律宾超级台风海燕之后的类似观测表明，稳健的灾害评估必须基于长期不同震级的极端波浪事件 (EWE) 的发生。虽然东南亚现代和历史上的热带气旋和海啸的频率-震级信息仅限于几个世纪，但地质印记可能涵盖数千年的时期，并记录了异常震级和低频的 EWE。2004 年的 IOT 引发了对受影响最严重的地区的深入研究。地区，人们对缅甸的 EWE 矿床仍然知之甚少。因此，尽管缅甸面临着来自三个主要来源的沿海洪水，但异常热带气旋和海啸造成的长期危害却很难得到遏制：(i) 孟加拉湾产生的向东移动的热带气旋（例如纳尔吉斯热带气旋）； (ii) 巽他弧北苏门答腊岛安达曼段完全破裂引发的海啸（例如 IOT 2004）； (iii) 缅甸西部近海若开邦（若开邦）段破裂引发的海啸（例如 1762 年海啸）。由于缺乏调查至少部分是由于过去几十年缅甸政治孤立导致研究活动有限，我们假设 EWE 的地质证据存在于合适的近岸地质档案中；这些有助于加深对长期海啸和气旋灾害的了解。虽然仰光大学和科隆大学之间的合作为拟议研究提供了先决条件，但由于 EWE 沉积物保存不良或稀缺，建议对几个地点进行调查而不是对个别地点进行系统调查。因此，应使用轻型设备对缅甸沿海6-8个滩脊平原进行测量，对EWE地貌（风暴脊、冲刷扇）和沙床进行水准测量（DGPS）和采样（沟渠、推芯）。结合沉积学（粒度测定、动物群、矿物学、地球化学）和年代学（放射性碳、光激发光）实验室分析，拟议的调查将通过以下方式触发后续项目：（i）为有希望的地点的系统调查提供基础； (ii) 将知识传授给参与实地调查的当地毕业生。