由於台灣海域位在不穩定的菲律賓海板塊與歐亞板塊的聚合帶上，北有琉球隱沒帶向西接觸台灣，南有馬尼拉隱沒帶向北靠近台灣。在不穩定的板塊邊界容易產生地震，地震引起的地殼垂直位移可以產生海嘯。同樣地，地震極可能誘發海底山崩進而引起近距離(近源)海嘯。近距離的海底山崩引起的海嘯不容易有足夠的時間反應，往往對局部岸邊造成重大破壞和損失。瞭解海底山崩可能發生的位置和可能的山崩大小，是研究海底山崩可能誘發海嘯的重要議題，瞭解海底山崩的潛在危機可以使我們增加可能海嘯的預警能力。在此計畫中，我們希望持續調查研究台灣海域可能的海底山崩位置、型態及可能的海底山崩規模，不但可藉以預警可能的海底山崩，也可以知道台灣海域較精細的構造斷層型態和分布。此為第二年計畫，持續在台灣北部及東北角外海及沖繩海槽的北邊大陸斜坡區域作多波束水深及淺層震測調查，藉以系不了解基隆海谷和棉花峽谷間陸棚可能引發海底山崩的位置和大小。此研究區域有許多海底峽谷切穿大陸邊緣，因有活動的弧後盆地擴張，大陸斜坡屬於較不穩定的區域 ; The offshore area of Taiwan is located at the convergent zones between the Philippine Sea Plate and the Eurasian Plate. In the north, the Philippine subducts beneath the Eurasian Plate In the south, the Eurasian Plate subducts beneath the Philippine Sea Plate. Such a complicated convergence has caused frequent earthquakes. The vertical motion of the upper crust caused by earthquakes may produce disastrous tsunamis. Moreover, earthquakes can trigger submarine landslides and then generate near-source tsunamis. The submarine landslide tsunamis occurred near-coasts cannot allow much time to response and take some emergency procedure, which generally causes large damage on the coastal zones. Investigating possible submarine landslides locations and magnitudes is an important issue of studying the tsunamis triggered by submarine landslides. Understanding the potential submarine landslides offshore Taiwan can increase our capability of tsunami warning. In this 3-year project, we expect to investigate the possible locations and patterns of the submarine landslides off Taiwan. The surveyed area is divided into the several areas and will be surveyed year by year. Overall, we will first study the area off northeast Taiwan and the northern continental margin of the Okinawa Trough. In this area, several submarine canyons have cut down the continental slope. Because of the active back-arc rifting, this continental slope area is supposed to be unstable. We will also study the area off southwest Taiwan and the northern Manila subduction zone. To the west of the study area, it belongs to the South China Sea continental margin. To the east, the area is a part of the Manila subduction complex. Similarly, earthquakes or some other mechanisms may induce submarine landslides from the unstable continental slopes. For example, in December 2006, two M 7.0 earthquakes have occurred off SW Taiwan and induced submarine landslides and turbidity current. The consequence is that several telecommunication cables have been broken. In this second year of the project, we still focus on the northern margin of the southernmost Okinawa Trough. I will continue doing multibeam bathymetry and shallow seismic surveys in order to identify potential submarine landslide locations. ; 研究期間 9808 ~ 9907
