A study on dynamic rupture process of an asperity and radiation of short-period seismic waves

我们通过数值模拟研究了周围抗震滑动引起的边缘应力集中的影响。无震滑动引起的应力集中促进了地震破裂的提前发生。这导致地震的平均应力降较低。凹凸体边缘的这种应力集中效应可以解释板内地震和板间地震之间平均应力降的差异。微凸体边缘的应力集中影响微凸体的破裂过程，微凸体破裂的平均应力降随断裂能或临界滑移弱化距离的增大而增大。对圆形凹凸体的动态破裂过程进行了数值模拟，其中凹凸体边缘产生应力集中。地震破裂从应力集中边缘的一点开始，沿边缘两侧传播。由于破裂前沿聚焦，在破裂结束时产生显著的滑移脉冲。我们对包络反演法估计的断层上的短周期地震能量辐射的空间分布进行了汇编，得到了地震能量辐射的标度律、频率依赖性和局部性。

We investigate effects of stress concentration at the rim of an asperity due to surrounding aseismic sliding through numerical simulations. The stress concentration due to aseismic sliding promotes earlier occurrence of seismic rupture. This results in lower average stress drop of earthquake. This effect of stress concentration at the rim of asperity may explain the difference in average stress drop between intraplate and interplate earthquakes. The stress concentration at the edge of an asperity affects rupture process of asperity, and the average stress drop of asperity rupture increases with fracture energy or critical slip-weakening distance. A numerical simulation is conducted for dynamic rupture process of a circular asperity, where stress concentration is generated at the rim of the asperity. Seismic rupture starts from a point of the stress concentrated rim and propagates bilaterally around the rim. A significant slip pulse is generated at the end of the rupture due to rupture front focusing. We compile spatial distributions of short-period seismic energy radiation on faults estimated from the envelope inversion method to obtain the scaling law, frequency dependence of seismic energy radiation, and locality.