相對強度(RI)就是地震發生在空間上密度，其計算方式是將地圖上每點地震震央在某時間區間內總和起來，再除以地圖上各點上之地震數目，就是地震密度。其基本想法就是在那些地震密度分佈異常的地方，就是將來有可能發生大地震之處，所以相對強度(RI)若超過一個門檻值就做為一個危險地區。本論文將相對強度之穩定性做為研究探討內容，透過不同厚度分層、不同網格大小、不同時間區間及不同門檻值等方法研究探討其穩定性。 Relative Intensity (RI) shows the intensity of earthquake that had happened in a space. RI is estimated by dividing the number of epicenters on the map within a specific period by the number of earthquakes occurred at those epicenters. The main idea is that those places with abnormal RI indexes may be the most probable places at which strong earthquakes occur in the future. Therefore, a place would be considered a dangerous area if its Relative Intensity (RI) surpasses the security critical point. This thesis focuses on the stability of RI and elaborates on the stability of RI through different layer depths, net sizes, time periods, and security critical points.