地震活动性模拟方法及太原地区地震活动性模拟

本文改进了地震活动性模拟方法,使模型可以使用GPS反演得到的断层滑动速率的结果作为应力加载,进行区域的地震活动性模拟.选取太原地区作为研究区域,模拟并分析太原地区地震活动性.计算太原地区长达20000年的理论地震目录,通过对理论地震目录进行分析发现模拟结果的震级频度关系与实际观测资料具有相似性.太原地区的震级大于6级的模拟地震在时间上表现出很强的随机性,与年平均发生率为0.0129a~(-1)的Poisson过程对比,当采用卡方检验进行检验时,置信水平达到99.0%;然而,单一断层的强震的时间分布与相应年平均发生率的Poisson分布并不完全相近,部分断层拟合置信水平为90%左右,部分断层置信水平接近为0.这一结果表明,用Poisson过程估计太原地区长期地震发生率是比较合理的,估计单一断层上的地震危险性不是十分合理.地震危险性模拟结果显示,太原盆地地区7级以上地震的复现周期为4000年.

Research of seismicity simulation method and its application in Taiyuan Region of China

In this study, we improved the seismic activity simulation method by using the fault rupture velocity derived from GPS data as stress loading to simulate the seismicity of the region. The new model was applied to simulate the seismic activity in the Taiyuan region of Northern China. A synthetic catalogue over 20000 years was simulated with the simplified fault model of Taiyuan Region, and the magnitude-frequency curve of the simulated catalogue matches well with that of observed catalogue. According to the analysis of the simulated synthetic seismic catalogue, occurrence of strong earthquakes with magnitude over 6.0 was rather random and very close to the Poisson process with seismic rate 0.0129a^-1. The time process of simulated earthquakes of magnitude over 6.0 showed a confidence level up to 99.0% as regarding the correlation with a Poisson process of λ=0.0129. However, the simulated earthquakes on individual faults in the region cannot be approximated by Poisson model. The confidence level was about 90% on some faults, but it was almost zero on other faults. Thus, it was reasonable to estimate the long-term seismicity for the whole region rather than to estimate that for an individual fault in the region. In terms of the result of seismicity simulation, the recurrence period of strong earthquakes with magnitude over 7.0 in Taiyuan Region was 4000 years.