本研究旨在利用跨越二次事件（一為颱風、一為地震，分別為民國98年8月4日在恆春鵝鑾鼻東方海面生成之莫拉克颱風(MORAKOT)及民國99年3月4日在南部發生之芮氏地震規模6.4的桃源大地震）前後之衛星影像資料，以高雄荖濃溪流域旁之六龜區為例，利用與地震危害度諧和(hazard consistent)之成對震力參數(最大地表加速度PGA及地震規模M)，考慮地文因子之變異性，應用蒙地卡羅模擬(Monte Carlo simulation)來分析及探討邊坡受震後之Newmark永久位移量及其受不同事件之影響，並繪製對應475年及2475年地震回歸期之永久位移危害度空間分布圖。研究結果顯示，莫拉克颱風後所造成坡地受震位移之相對影響程度，要大於桃源地震後之相對影響程度。而其影響大小，與地下水位深度及地震力強弱，息息相關。另外，在莫拉克颱風後，隨時間經過，坡地植生情況漸有改善，雖再歷經桃源地震，但總體而言，坡地受震位移已較颱風剛過不久時減少，可見植生之效用。 Seismic-induced landslide is a common type of ground failure during an earthquake. Susceptibility evaluation of landslide displacement is thus an important issue for earthquake disaster prevention and risk management. The hazard analysis of seismic-induced landslide displacements is one of the essential parts for those objectives. Moreover, the effect of variations of hillside properties caused by the change of external environment should be considered in the analysis.
In this research, a method to construct the GIS-based hazard map with return period of 475 and 2475 year for Newmark displacement by hazard-consistent seismic parameters using Monte Carlo simulation (MCS) is proposed. The pair of earthquake magnitude (M) and the associated peak ground acceleration (PGA) can be considered simultaneously. The uncertainties and variability of associated analysis parameters are all included in the MCS analysis. A case study of Liugui District in Laonong River Basin with three different time periods divided by Typhoon Morakot on 9 August, 2009 and Taoyuan earthquake on 4 March, 2010 with ML=6.4 is performed using the digital elevation model (DEM) and satellite image. It is showed that the influence of Typhoon Morakot on Newmark displacement is larger than those of Taoyuan earthquake. The magnitude of displacement is largely influenced by the ground water level and the characteristics of earthquake. The state of vegetation is another important factor influencing displacement based on the fact that lower displacement was observed after some period of both events of Typhoon Morakot and Taoyuan earthquake, in which vegetation on hillsides become well compared to before.