Dynamic rupture process of the 2018 Hokkaido Mw6.6 earthquake,Japan
On 5 September 2018,a Mw6.6 earthquake occurred in the Eastern Iburi of Hokkaido,Japan,with a focal depth of 37 km,exceeding the depth of the brittle-ductile boundary between the crust and the upper mantle,and caused severe damage by strong ground motion.In order to investigate the seismogenic structure and the physical mechanism generating strong ground motion in the source area of the Hokkaido earthquake,this study focuses on the dynamics of this earthquake,and attempts to invert the dynamic rupture process based on its kinematic source model.Firstly,the shear stress on the fault plane is analyzed and calculated by the kinematic source model,determining that the rupture process basically follows the slip-weakening friction law,and thus obtaining the dynamic source parameters of an initial model.Subsequently,the dynamic rupture process of this earthquake is inverted by the trial-and-error method.The results show that the dynamic source rupture process of the Hokkaido earthquake is dominated by strike-slip in the rupture initiating area,and propagates first toward NE and then toward SW,and finally propagates toward the up-dip direction of the fault plane,producing thrust rupture at the bend of the fault geometry.At the position of thrust rupture,the slip rate and total slip reach their maximum values.Combined with the analysis of kinematic and dynamic inversion results,it is inferred that the region is a strong motion generation zone,and the high-frequency ground shaking generated at the ground surface is the main cause of the strong destructiveness of this moderate earthquake with deep source.
2018 Hokkaido earthquakeFriction lawDynamic ruptureSpectral element method
万方数据
