| 摘要: | 本年度之研究將接續去年之成果，除探討與還原台灣西南部歷史海嘯可能的情境外，本年度將發展新的海嘯到時分析法，以搭配去年已發展完成海嘯影響強度分析法（IIA），並應用於海嘯近源區域之分析。IIA法可快速濾除海嘯源低度影響之區域，有效減少海嘯情境個數。然而對於方向性較強之海嘯，則較不容易掌握。因此，為克服此缺點，本年度將開發海嘯到時分析法（TATA）。若相鄰單元海嘯源（UTS）有近似之海嘯到時，則海嘯波抵達研究場址之波高將會放大，由此可了解海嘯方向性對於研究場址之影響。 學界目前對於台灣西南沿海歷史海嘯研究相當缺乏，更遑論進行系統性的分析。然而新加坡南洋理工大學於2015年，在GRL期刊上發表了一篇以「甚麼原因造成18世紀侵襲台灣西南海岸的神秘海嘯」為題之文章。認為包含台灣采訪冊在內的三篇中外史料上所記載之大規模海嘯事件，主要是肇因於台灣西南外海高屏斜坡上之海底山崩所引發之海嘯。文中並強調現今在台灣西南部，人口已逾三百萬，並已增建核電廠，若再度發生海嘯，恐怕會有災難。此文一出，造成台灣很大的迴響。其中部分原因是該文中部分論述並不合理，會造成民眾的誤解與恐慌。 在事件分析方面，將針對1781高屏海嘯事件、1782台南大海嘯事件、1894東港海嘯事件和1661鹿耳門水漲事件之來源進行分析，並以COMCOT海嘯模式進行情境重建。其中，1661鹿耳門水漲事件在去年已有相當之進展，並已於EGU與AGU進行口頭報告（Oral Presentation），其中除探討地震型海嘯之外，並以首度發展完成之不連續雙黏性流（Discontinuous Bi-viscous Model，DBM），模擬海底泥流之運動行為。該研究結果受到相當的肯定。本年度亦將利用DBM模式，了解台灣西南陸棚斜坡上的山崩型海嘯對於台灣西南沿海的可能威脅。 ;This year, we shall continue the research with the results yielded from last year. Apart from exploring and restoring the possible scenarios of the historical tsunami in southwestern Taiwan, a new Tsunami Arrival-Time Analysis, TATA, will be derived to match the method of the tsunami Impact Intensity Analysis (IIA) developed last year. Both methods will be applied to the near-field tsunami analysis. The IIA method can quickly filter out the low-impact area of the tsunami source and effectively reduce the number of tsunami scenarios. However, for a tsunami with strong directionality , it is less easy to grasp. Therefore, in order to overcome this shortcoming, the tsunami-arrival-time analysis (TATA) will be developed this year. With a similar tsunami arrival time of the adjacent unit tsunami source (UTS), the tsunami height on the study site will be magnified. Combining IIA with TATA, one can understand the potential tsunami threat more precisely. The southwest coast of Taiwan is not only densely populated, but is the place with the most historical tsunami records as well. Unfortunately, in Taiwan, no scientific researches are constructed so far to perform a systematical analysis on this area. In October 2015, a scientific paper, titled "What caused the mysterious eighteenth century tsunami that struck the southwest Taiwan coast?” by Nanyang Technological University, Singapore, was published in the Journal of Geophysical Research Letters. In that paper, a Chinese historical document, “Taiwan Interview Catalogue,” and two other historical accounts in English and in French were referred. The study concluded that the large tsunami depicted in the above-mentioned documents was most likely generated by submarine mass failure on the Kaoping slope. This paper also warns that a catastrophe will be expected if a tsunami with a similar scale attacks this area again． In this project, a more rapid Tsunami Volume Flux Method (VFM) will be developed to identify, with higher efficiency, the potential tsunami sources in a large scale. Four particular tsunami events, including the 1781 Kaohsiung- Pingtung Tsunami Event, 1782 Tainan Tsunami Event, 1894 Tonggang Tsunami Event and 1661 Luermen Water Level Rise Event, will be targeted to analyze their event sources and COMCOT will be employed to reconstruct the event scenarios. Among all four cases, we have made a good progress on 1661 Luermen Water Level Rise Event and presented the result in an oral format at both EGU and AGU in 2016. T study of 1661 Luermen Water Level Rise Event discussed the earthquake-generated tsunami and developed a brand new Discontinuous Bi-viscous Model (DBM）in a complete version for the first time in this field to simulate a mudslide movement under the sea. This stunning development has received significant academic approval. Therefore, DBM will be implemented in this project to better study the landslide-generated tsunamis on the southwest shelf slop of Taiwan and the threats they pose to the southwest coast of Taiwan. |
