论文部分内容阅读
1973年 2月 6日在四川省炉霍发生MS7 6大地震 ,震后在震中周围出现丰富的余震 ,其最大余震 (MS6 3)发生在鲜水河断裂和玉树 -甘孜断裂之间的正断层活动区内。本文根据震源机制解、地表破裂、同震位错分布、地震地质构造等资料 ,建立炉霍走滑大地震破裂的弹性位错模型 ,计算该大地震在周围正断层滑动方向上引起的库仑破裂应力变化 (ΔCFS)。结果表明 ,最大余震发生在库仑破裂应力增加 (ΔCFS >0 )的地区 ,ΔCFS =4 5MPa。因此认为 ,最大余震可能是由主震引起的库仑破裂应力变化触发的。
On February 6, 1973, MS7 6 earthquake occurred in Luhuo, Sichuan Province. After the earthquake, there were abundant aftershocks around the epicenter. The largest aftershock (MS6 3) occurred in the normal fault between Xianshuihe fault and Yushu-Ganzi fault Activity area. Based on the focal mechanism solution, surface rupture, dislocation distribution of coseismic dislocation and seismic geologic structure, this dissertation establishes the elastic dislocation model for the rupture of the large-scale furnace-slip strike-slip earthquake and calculates the Coulomb failure caused by the earthquakes in the surrounding normal fault slip direction Stress changes (ΔCFS). The results show that the maximum aftershock occurred in areas where the Coulomb failure stress increased (ΔCFS> 0), ΔCFS = 45 MPa. Therefore, the largest aftershock may be triggered by the Coulomb failure stress caused by the main shock.