基于库仑应力变化分析2015年尼泊尔MS8.1地震对中国大陆的影响

本文采用分层黏弹性介质模型, 模拟了2015年4月25日尼泊尔M_S8.1地震产生的同震和震后地表位移场, 计算了尼泊尔大地震引起的青藏高原及其周缘主要断裂上的同震和震后库仑应力变化。 地表位移场结果显示, 此次尼泊尔8.1级地震对中国大陆的影响区域主要是拉萨地块和羌塘地块, 对拉萨块体的影响主要表现为水平向南朝喜马拉雅构造带的汇聚作用, 垂直同震位移以下降为主, 震后以上升为主。 静态库仑破裂应力变化的计算结果显示, 尼泊尔大地震对青藏块体中南部的拉张性断层影响最为显著, 其中, 使尼泊尔地震北部的拉张断层的库仑应力显著增加, 个别断层库仑应力增加量超过0.01MPa, 而使其两侧的拉张断层库仑应力明显降低; 对青藏块体中部的走滑断裂则以正影响为主; 另外, 对南北地震带主要以负影响为主, 但量值微小。

Effects of the 2015 Nepal Ms8.1 Earthquake on Mainland China based on Coulomb Stress Changes

Using the multi-layered viscoelastic media, we simulated coseismic and postseismic surface displacements caused by the April 25, 2015 Nepal M_S8.1 earthquake, and then calculated the Coulomb failure stress changes on major faults of the Tibetan plateau and its surrounding caused by the coseismic dislocation and postseismic viscoelastic relaxation effects of the Nepal large earthquake. The surface displacement shows that the Nepal large earthquake mainly influences the Lhasa block and Qiangtang block, making the Lhasa block converge to the Himalayan tectonic belt. Vertical displacements of the Lhasa block predominately drop down in the coseismic stage and rise up in the postseismic stage. The calculated results of the static Coulomb failure stress changes indicate that, the Nepal large earthquake significantly influence tensional faults in central and southern Tibetan plateau, among the faults, the tension faults in the north of the Nepal earthquake take a significant increasing of Coulomb stress and the Coulomb stress in some specific fault segments increase more than 0.01 MPa, while the tension faults on both sides of the earthquake have a significant decreasing of Coulomb stress. In addition, Coulomb stress changes on the strike-slip faults in central Tibetan plateau are mainly increased which has been caused by the Nepal large earthquake, however, Coulomb stress changes on the faults of the North-South Seismic Belt are mainly slightly decreased by the Nepal large earthquake.