The Scenario Reconstruction of the Historical Tsunami Events on the Southwest Coasts of Taiwan (III)

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 In that paper, a Chinese historical document, “Taiwan Interview Catalogue,” and two other historical accounts in English and in French were referred.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.