本研究旨在分析18世紀發生於臺灣之兩次歷史海嘯，藉由耙梳歷史文獻蒐集線索，並以數值模式進行事件重建，最後評估臺灣西南部之潛在海嘯風險。兩次歷史海嘯事件分別為：《臺灣采訪冊》記載之西元1781年（乾隆四十六年四、五月間）台灣西南沿海與加藤港海水暴漲，與以外國文字記錄卻無確切時間之西元1782年海嘯。本論文亦審視同樣發生於1782年四、五月之臺灣風災中外文獻，以進行歷史文獻交叉比對。探討這兩起歷史海嘯事件，除須悉心整理和比對文獻記錄外，亦進行多種情境數值模式與分析。本研究使用影響強度分析法（Impact Intensity Analysis, IIA）及海嘯到時分析法（Tsunami Arrival-Time Analysis, TATA）協助還原歷史海嘯事件，定位海嘯源之可能所在區域，並以康乃爾大學開發之多重網格海嘯模式（Cornel Multi-grid Coupled of Tsunami Model, COMCOT）進行數值模擬，分析局部海底山崩與馬尼拉海溝地震活動所產生之海嘯及其影響。模擬結果顯示，1781年加藤港暴漲之海嘯源頭位於東港研究場址之西南偏南側。然而，經數值模擬暨歷史文獻記錄交互分析，1782年海嘯事件之存在應受質疑與進一步檢視，並不排除其為風暴潮事件之可能性。最後，本研究以影響強度分析法進行今日臺灣西南沿海地區之海嘯風險評估。結果顯示近源海嘯波可能於海嘯發生後三十分鐘內抵達西南沿海地區，故當地區居民的疏散時間十分有限。;This research aims to study two of the historical tsunamis occurred in Taiwan during the 18th century and to reconstruct the incidents, as well as to assess the tsunami hazard in coastal arears of the southwestern Taiwan. The 1781 Jiateng Harbor Flooding, recorded by the Chinese historical document, Taiwan Interview Catalogue, took place on the southwest coast of Taiwan. On the other hand, the 1782 Tsunami was documented in foreign languages, with uncertainties of the actual time. Reasoning these historical events requires not only carefully examining the literature records but also performing the scenarios that match the descriptions. The Impact Intensity Analysis (IIA) and the Tsunami Arrival-Time Analysis (TATA) method are employed to locate possible regions of tsunami sources in order to reproduce the events. Numerical simulations based on the Cornell Multi-Grid Coupled Tsunami Model (COMCOT) analyze the influence of different types of tsunami generated both by submarine landslides in the localized area and seismic activities of Manila trench. Numerical results indicate that the source of the 1781 Jiateng Harbor Flooding very possibly located at the South South-West side of Donggang. However, simulation results and historical records put the existence of 1782 Tsunami in doubt, and the possibility of storm surges could not be ruled out. Finally, IIA simulations are carried out to assess up-to-date tsunami hazard in coastal arears of the southwestern Taiwan. Results show that for a nearby origin, tsunami waves would arrive at the coastal region in less than 30 minutes, and local residents would have very limited time to evacuate.
