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采用β统计对汶川地震前后鄂尔多斯块体周缘地区的地震活动率进行了空间扫描分析,并采用JiChen的震源破裂模型计算了汶川地震产生的库仑破裂应力变化,以研究鄂尔多斯块体周缘地区近期地震活动性与汶川地震应力触发作用的关系。结果发现,鄂尔多斯块体西南缘弧形断裂束的南东段与南缘渭河盆地的地震活动率在汶川地震后提高显著,其他区域的地震活动率没有明显提高,库仑破裂应力计算得到两个区域的应力变化范围分别为0.005～0.02 MPa和0.001～0.01 MPa,表明汶川地震有可能触发了这两个区域的地震活动。鄂尔多斯块体东缘的山西断陷带处于库仑破裂应力计算的应力增加区,应力变化范围为0～0.012 MPa,2009年3月以来发生的4次ML4.5～5.2级强有感至微破坏地震有可能被汶川地震所延迟触发。b值、地震能量释放率与空间相关距离SCL等地震活动性参数随时间变化扫描结果显示,该区域可能处于不断趋近高应力累积的状态,其未来大震有可能提前发生。西缘地区为应力减小区,其目前的地震活动处于正常水平状态。
The β-statistic was used to analyze the seismicity of Ordos block in the area before and after the Wenchuan earthquake. The Coulomb rupture stress of the Wenchuan earthquake was calculated by JiChen earthquake rupture model to study the recent seismic activity in the peripheral area of Ordos block RELATIONSHIP BETWEEN SEISMICITY AND STRESS TRIGGERATION IN WENCHUAN EARTHQUAKE. The results show that the seismicity of the Weihe Basin and the southwestern margin of the arc fracture in the southwestern margin of Ordos Block increased significantly after the Wenchuan earthquake, while the seismicity of other regions did not increase obviously. The Coulomb failure stress calculated two regions Of the stress range of 0.005 ~ 0.02 MPa and 0.001 ~ 0.01 MPa, respectively, indicating that the Wenchuan earthquake may have triggered the seismic activity in these two regions. The Shanxi fault zone on the eastern margin of the Ordos block is in the area of stress increase calculated by Coulomb failure stress with a stress range of 0 ~ 0.012 MPa. Four ML4.5 ~ 5.2 levels occurred since March 2009 are strongly susceptible to micro-destructive Earthquakes may be delayed by the Wenchuan earthquake triggered. The time-dependent changes of seismic activity parameters such as b value, seismic energy release rate and space-related distance SCL show that the region may be in the state of continuous accumulation of high stress and its future earthquakes may occur ahead of time. The western margin is a zone of stress reduction and its current seismic activity is at a normal level.