- 學位論文
單站地動預估式建立及場址特定地震危害度分析
Single-station Ground Motion Prediction Equation and Site-specific Seismic Hazard Analysis
摘要
台灣地震頻繁，重要工程如核電廠及大型水庫，會進行個案的地震評估，擬定設計地震參數，此技術稱為地震危害度分析(seismic hazard analyses)。分析過程須評估震源規模、震源距離及工址震度大小，其中震源釋放地震波隨距離傳遞至工址之震度預測關係式或稱地動預估式(ground motion prediction equation，GMPE)研究尤為重要。過去的危害度分析所使用的地動預估式是以全區域內多個測站記錄到多個不同震源的強地動紀錄所建立的，包含過多的地動值變異性，會造成危害度過估。 本研究在地震資料上選用單一場址來進行分析，建立更適合該場址的地動預估式，以合理地計算危害度。研究過程中先選用來自中央氣象局的自由場強地動觀測網計畫(TSMIP)豐富之強震資料，共30602筆紀錄，完成台灣地區地殼地震全區地動預估式，再分別進行9個不同單站的地動預估式分析。分析結果顯示單一測站標準差比全區標準差(0.626)下降9%至33%，並以單站地動預估式建立場址特定地震危害度分析，以再現期2475年為例，顯示以單站地動預估式分析危害度比全區結果下降11%至48%。若地動預估式再進一步引入震源分區，單站標準差相較全區下降16%至36%，危害度結果較使用全區地動預估式可望下降更多。
並列摘要
Due to frequent earthquakes in Taiwan, Probabilistic seismic hazard analysis (PSHA) is a common approach to evaluate potential earthquake motions at sites of critical facilities such a nuclear power plant and dams. It includes the estimation of the earthquake magnitude and distance of source, and earthquake intensity at a site. Ground motion prediction equation (GMPE) reflects the fact that the amplitude of the ground-motion increases with earthquake magnitude and decreases with propagation distance. Modern GMPEs are based on datasets of ground-motion parameters recorded at multiple stations and different earthquakes in various source regions. It causes excessive variability and leads to increase seismic hazard estimates. In the present study, only strong-motion data record at a site is selected to establish a GMPE. We processed strong-motion data from TSMIP in Taiwan which used these data to establish GMPEs. A total of 30602 records are selected and are used to accomplish the regression analysis of a regional GMPE in the first step. Then, 9 stations are selected to complele a single-station GMPE, respectively. The results reveal that the sigma of the regional GMPE is 0.626 in ln unit and the sigma of single-station GMPE is ranging 0.416 to 0.567. The single-station sigma is about 9% to 33% reduction from the regional one. When PSHA is performed by adopting the single-station sigma, the hazard is 11% to 48% smaller then that regional sigma is used. If source zones are further involved in GMPEs, the sigma of single-station GMPEs can reduced 16% to 36% relative to regional GMPE's. It is expected to further reduce the result of seismic hazard analysis.