大規模的海嘯災難通常是隱沒帶的板塊間淺層逆衝地震所引起。因此，台灣地區最主要的海嘯災害誘發源在南邊的馬尼拉─台灣隱沒帶和東北邊的琉球隱沒帶。在考慮建立南中國海的海嘯警報系統時，有能力評估馬尼拉─台灣隱沒帶發生超級大地震(Mw > 8.5)的機率至為關鍵。在一給定的板塊邊界，地震的發生本身是變異的，再加上有地震資料時間很短，使得使用地震資料來預測大地震的機率未獲得太大的成功。然而，現存的地震目錄在分析可能發生大地震的位置、發生週期、以及板塊運動的速率以地震型式釋放的比率，都提供了有用的資訊。本研究計畫即是由不同的地震目錄，包括有儀器記錄以來的地震目錄、現代的地震目錄(the EHB catalogue)、和哈佛的地震目錄(the Harvard CMT catalogue)，來分析馬尼拉─台灣隱沒帶(1)過去百年來發生相當規模地震的位置，並根據海嘯目錄查閱相關海嘯災害文字說明、(2)地震發生頻率與規模的線性關係，並根據此結果推算一定規模地震的發生週期及未來一定時間內的發生機率、(3) 估計板塊間斷層地震偶合部分的比率，並計算其隨著區域內最大地震的規模值的函數變化。 ; Earthquakes that cause devastating tsunamis are shallow events in subduction zones. Accordingly, one of the major sources of tsunami hazards for areas around the South China Sea is major earthquakes in the Manila Trench, Luzon Trough and Taiwan subduction system. The capabilities of estimating the likelihood of occurrence of mega-earthquakes (Mw > 8.5) thus become one of the key elements in building the South China Sea tsunami warning system. Although forecasting of mega-earthquakes using seismological data has been unsuccessful due primarily to variability of earthquakes on a give plate boundary and short time sampling, existing earthquake catalogue remain valuable regarding potential largest earthquake on a given plate boundary, its frequency, and fractions of plate motions taken up seismically. We thus propose to conduct a study on existing earthquake catalogue to review the seismic behavior of the Malina-Taiwan subduction zone. Available catalogue are the instrumentally recorded catalogue, the EHB catalogue and the Harvard CMT catalogue. The expected results are the largest earthquakes in the area for the past century and their corresponding tsunami hazards documented, the frequency of earthquake for certain magnitude and its probability in the future for predefined time interval, and the fraction of seismic shortening rates relative to plate motion both for observed data and for projected largest earthquake that will occur in the future. Meanwhile, for recent earthquakes in the area where broadband waveforms of GSN (Global Seismography Network) are available, we will analyze their E/M0 ratio to investigate features of tsunami earthquakes and will study the source processes by waveform inversions. ; 研究期間 9708 ~ 9807
