| 摘要: | 本研究旨在建立臺灣機率式地震危害評估的地震源模型，其分為淺層區域震源、孕震構造震源與隱沒帶震源，而隱沒帶震源又細分為板塊介面型與板塊內部型震源。本研究重新劃分淺層地殼區域震源，並整合七個地震目錄，考量自1900年至2022年之地震，以三種方法去除目錄之前、餘震後，計算各區域的地震活動度。本模型採用更新的陸域孕震構造與新辨識的海域孕震構造的相關參數計算孕震構造的再現週期，其中部分孕震構造考慮複合構造破裂與時變性地震機率模型—布朗過程時間，評估孕震構造隨時間變化的發生機率。隱沒帶板塊介面型震源則參考TWSSHAC Level 3地震源特徵模型中海溝線型與滑移速率，依據前人文獻建立板塊幾何，計算再現週期。隱沒帶板塊內部型震源參考三維板塊模型，並假設板塊厚度為50公里，依據地震分布重新劃分隱沒帶內部型震源的區域，並計算各區域地震活動度。在考慮孕震構造和隱沒帶介面型震源地震規模與長期滑移速率的不確定性之後，結合地動預估式與場址參數，進行地震危害評估。結果顯示，南臺灣在最大地表加速度的地震危害分布圖中有最大的地震動，而花蓮則在大部分的最大地表加速度與譜加速度週期0.3秒有最小的超越機率，相較於其他區域有更大機率發生相同程度的地震動。而在拆解分析中顯示，隱沒帶在最大地表加速度的地震危害中的貢獻程度甚小，但在長周期譜加速度中有更多的貢獻，尤其在臺北市、新北市、臺南市與高雄市更為明顯，這些地區應注意地震對於高樓層建築的影響。在依據新數據建立機率式地震源模型以更符合近期之研究，本研究之成果將有助於後續地震風險分析研究以及公部門防災策略推動，如：大規模地震情境模擬、地震災害避難防救演練腳本等。;This study aims to establish a seismogenic source model for probabilistic seismic hazard assessment (PSHA) for Taiwan, which is divided into shallow area sources, seismogenic structure sources, and subduction zone sources. The subduction zone sources are further categorized into interface and intraslab sources. The study redefines the region of shallow area sources, integrates seven catalogs and considers events from 1900 to 2022. After removing foreshocks and aftershocks using three different de-clustered methods, seismic activity rates for each region were calculated. The model incorporates updated inland seismogenic structures and newly identified offshore structures to compute their recurrence intervals. For some structures, multiple structures rupture and time-dependent seismic probability model, the Brownian Passage Time model, are considered to evaluate time-dependent rupture probabilities. The geometry and corresponding parameters of the subduction zone interface sources are based on the trench lines and the slip rates of TWSSHAC Level 3 Seismic Source Characterization model, and recurrence intervals are calculated using established plate geometries from previous studies. For subduction zone intraslab sources, a 3D plate model assuming a thickness of 50 km is used. The regions are redefined based on earthquake distribution, and seismic activity rates for each region are calculated. After considering uncertainties in earthquake magnitudes and long-term slip rates for seismogenic structures and subduction zone interface sources, combined with ground motion prediction equations and site parameters, seismic hazard assessments were conducted. Results indicate that southern Taiwan exhibits the highest ground motion in the peak ground acceleration (PGA) hazard map, while Hualien has the lowest exceedance probability for most PGA and spectral acceleration with a period of 0.3 second. Hualien also shows a higher likelihood of experiencing similar levels of ground motion compared to other regions. Disaggregation analysis reveals that subduction zones contribute minimally to the seismic hazard in terms of PGA but have a more significant impact on long-period spectral accelerations. This is particularly evident in Taipei, New Taipei, Tainan, and Kaohsiung, suggesting that these regions should pay special attention to the impact of earthquakes on high-rise buildings. By developing a probabilistic seismic source model based on new data to reflect recent research, the results of this study will aid in future seismic risk analyses and the implementation of disaster prevention strategies by public authorities. Applications include large-scale earthquake scenario simulations and earthquake disaster evacuation and rescue drills. |
