台灣潛勢地震之發生機率評估

Estimation of The Potential Earthquake Probabilities in Taiwan

許京穎(Ching-Ying Hsu)

指導教授 ： 溫國樑

國立中央大學/地球科學學院/地球物理研究所/碩士(2008年)

摘要

台灣位於歐亞板塊與菲律賓海板塊之碰撞與隱沒地帶，地震活動十分頻繁，尤其台灣西部麓山帶的斷層多為活動性極高的新生斷層，對人口密集的都會區將會構成極嚴重的威脅，因此在本區從事地震觀測和地震研究是十分要緊的事。地震發生的原因受到許多複雜的因素與過程所影響，導致準確預測地震難以有關鍵性突破。在進行地震準確預測研究的同時，另一方面亦可以評估地震發生機率的方式幫助我們做各種長期規劃，如地震防救災規畫與建築物耐震設計評估等。 本研究將地震分為區域震源及斷層震源兩部分做分析，分別建立區域之潛勢地震機率模型與活動斷層之特徵地震機率模型，並計算各區域及活動斷層於未來10~50年內的地震發生機率。 區域震源方面，參考台灣電力公司核電廠耐震安全評估所使用震源分區「D」之淺層分區，假設地震的發生遵循柏松過程而對地震目錄去除各主震的前震及餘震，並統計地震間隔時間的分佈情形，發現log-normal、Weibull、Gamma三種曲線中，大部分區域較符合log-normal分佈，故本研究以此分佈建立各區域之潛勢地震發生機率模型。13個區域的地震機率計算結果顯示，地震危害潛勢較高者為s003、s006、s008、s009；較低者為s001、s004、s012。此結果顯示靠近板塊碰撞帶有較高的地震危害潛勢，遠離板塊碰撞帶則反之。 斷層震源方面，本研究以第一類活動斷層為分析對象，參考活動斷層參數調查的結果，建立各斷層之特徵地震機率模型，並計算其特徵地震發生機率。其中地震發生機率較高的有米崙斷層、新化斷層、大尖山及觸口斷層系統、梅山斷層。斷層地震機率最高的米崙斷層亦位於地震發生機率最高的s003區域，此結果凸顯了板塊碰撞邊界的高地震危害潛勢。 本研究利用台灣目前擁有的地震記錄與活動斷層調查參數，計算得到台灣各區域及斷層之地震發生機率，其結果可提供相關單位參考及應用。而未來隨著地震記錄的增加與活動斷層調查參數的更新，可再行評估以獲得更可靠的結果。

關鍵字

特徵地震 ； 地震機率 ； 再現週期

並列摘要

Taiwan is located on the boundary between Eurasia Plate and Philippines Sea Plate and earthquakes occur frequently. There are many youthful faults on the western Taiwan and it is dangerous to live in urban areas on these regions. For this reason earthquake study is important to Taiwan. Though earthquake forecast isn’t success completely today, we still need to estimate the earthquake potential and prevent disasters first. In this study, we separated the earthquake source into regional and fault sources, and calculated the potential earthquake probabilities in next 10 to 50 years respectively. For regional source, we analyzed the 13 regions, which used by Taiwan Power Company for Nuclear Power Plant’s seismic safety evaluation. The earthquake catalog cut out the fore- and after-shocks, and count the time interval between earthquakes. For the three distributions of Log-normal, Weibull, and Gamma distribution, we found that Log-normal distribution fit seismic data better in the most regions. Therefore we set up the earthquake probability models by Log-normal distribution, and calculate the probabilities for the potential earthquake of each region. The results shows that the s003, s006, s008, s009 regions have higher earthquake potential, and the s001, s004, s012 regions are on the contrary. It also signifies that it’s much dangerous in the boundary zones. For fault source, we refer to the active fault parameters investigated by the Central Geological Survey, MOEA, set up the characteristic earthquake probability model, and calculated the probabilities for the potential earthquake of each fault. The results shows that Milun Fault, Sinhwa Fault, Tachienshan Fault and Chukou Fault system, Meishan Fault have higher earthquake potential. And Milun Fault has the highest earthquake potential. In this study, we calculated the probabilities of regional and fault sources using earthquake data and fault parameters. It can provide as a reference. The earthquake data will increase with time and the fault parameters will renew in the future, then we need to estimate the earthquake probabilities afresh, to obtain much reliable results.

並列關鍵字

return period ； earthquake probability ； characteristic earthquake

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