摘要 : 根據歷史海嘯資料，大部分具威脅性的海嘯事件皆由隱沒帶上產生的海底地震所引起，因此海底地震發生的機制對於海嘯的發生及其所可能帶來的災害評估有很大的影響。在台灣西南部，由於歐亞大陸邊緣斜向聚合作用，使得馬尼拉隱沒系統產生了複雜地震構造特性。由於此區域位於海域，OBS臨時觀測網的設置是將是用來研究此區域發震原因的最佳工具。 除了地震產生機制的影響，許多研究更指出，海底地質構造的分佈與海嘯產生和其所造成災害的大小更有密切的關係。在台灣西南外海，震測資料的分析指出在馬尼拉海溝逆衝斷層前緣附近有許多盲逆衝斷層，此種高角度逆衝斷層的活動對於海嘯產生災害的評估是具有很大的影響的。但由於在此類逆衝斷層上產生的地震活動規模通常會較小，必須藉由OBS臨時地震網來對這些相對較微小的地震來做觀察。 因此，本研究希望以位於台灣西南方的馬尼拉海溝為研究區域，藉由臨時海底地震網的設置來從事此區域地震特性的研究和觀察，一方面藉以了解研究地區大地震產生的機制。另一方面希望藉由微震的分佈來研究海底地質構造的活動情形，並希望能藉此對於在馬尼拉海溝區域地震引發海嘯的潛勢和危害來做估計。 Based on historical tsunami research, most threatening tsunamis are generated by the undersea earthquakes produced by subduction zones. Therefore, earthquake mechanism plays a very important role for the understanding of the occurrence of a tsunami. In southwestern Taiwan, due to the oblique collision of the Eurasian continent, the Manila subduction system presents a very complex seismotectonic features. Located in the offshore Taiwan, a temporary OBS recording network is the best tool to study the seismogenic factor in this area. Besides the impact of earthquake generating mechanisms, many studies have further pointed out that the distribution of geological structures has much inference on the generation of tsunami and the produced disaster. Offshore southwestern Taiwan, the analysis of seismic reflection profiles shows the presence of the thrust faults in the leading edge of the Manila Trench. This kind of high angle thrust fault might induce larger surface movement and produce higher tsunami wave. However, the magnitude of earthquakes generated by such thrust faults is usually small; it must depend on a temporary OBS seismic network for the earthquake observation. In this project, we plan to analyse the data recorded by two passive OBS networks located close to the Kaoping canyon and Manila subduction zone. We except to characterize the seismicity in these specific areas in order to better understand the role of Manila subduction zone in the formation of Taiwan and its evolution through time and its relationship with the generation of earthquakes. On the other hand, we will use the micro-seismicity distribution patterns to study the geological structures. This geological map will give a good constrain for tsunami simulation. 研究期間：9908 ~ 10007
