华北地区地震危险性分析和地面运动预测的一致性方法

利用华北地区地震活动性资料,建立了地震危险性计算的一致性模型.在此模型的基础上,得出了北京、天津、唐山和济南等7个城市未来2500年内地震的时空强度分布,并计算了2500年回复周期的地震动峰值加速度(PGA).结果表明,唐山和太原的PGA最大(>0.2g),石家庄和北京次之(≈0.17g).对华北地区2500年地震记录的正演计算结果表明,太原和唐山地区的潜在地震危险最有可能来源于震级在6.0～7.0、震中距离在12～15km的地震活动;而北京、天津和石家庄地区则可能来源于震级在5.5～6.0、震中距离在10km左右的地震活动.采用IBC(International Building Code)方法计算后的结果显示,太原、唐山等地区的PGA与2001年我国地震动峰值加速度值基本一致,与此地区的较高地震活动性特征相符.利用随机震源模型,还给出了影响此7个城市的最大地震记录的加速度、速度及位移时程曲线,这对本区工程建筑的抗震性设计以及对救援设施的选址等有重要作用.

A Uniform Method of Seismic Hazard Analysis and Ground Motion Predicting in North-China Area

Using the seismicity data collected from the historical and instrumental records for the North China area, we have developed a uniform model for the seismic hazard assessment. We have simulated the earthquake intensity (magnitude in size) distribution in spatial domain for several major cities for the next 2500 years based on the stochastic principle, and derived the ground motion parameters, such as the peak ground acceleration (PGA), peak velocity and time histories etc. The result shows that Taiyuan and Tangshan have a maximal PGA, and are more than 0.2g; Shijiazhuang and Beijing are the second with the value about 0.17g. Through the forward modeling for the 2500-year earthquake catalog, we find that the maximal seismic hazard of Taiyuan and Tangshan is most likely from earthquakes with 6.0≤M_s ≤7.0 and distance from 12 to 15km, while that of Beijing, Tianjin and Shijiazhuang is most likely from earthquakes with 5.5≤ M_s≤6.0 and distance of 10km. Therefore, we believe that the model we have developed has a very important implication for the future seismic hazard assessment used generally in earthquake engineering design, risk analysis, and local agency decision making.