东昆仑活动断裂带大地震之间的弹性应力触发研究

STUDY ON THE ELASTIC STRESS TRIGGERING AMONG THE LARGE EARTHQUAKES IN EASTERN KUNLUN ACTIVE FAULT ZONE

摘要:

1937年以来沿青藏高原北部东昆仑断裂带发生了5个M_S ≥ 7的地震:1937年M_S 7.5花石峡地震,1963年M_S 7.1都兰地震,1973年M_S 7.3玛尼地震,1997年M_W 7.5玛尼地震和2001年M_W 7.8昆仑山口西地震.研究了大地震之间的应力转移和断层相互作用,计算了弹性半空间介质中地震断层错动在后续地震破裂面上产生的库仑破裂应力变化.结果表明,前面4个地震均造成后续地震的库仑破裂应力增加,有利于后续地震的发生.昆仑山口西地震之后应力变化场的计算表明东昆仑断裂中段的东大滩-西大滩段的库仑破裂应力显著增加,变化值达0.006~0.02 MPa,预示着这一地区地震危险性的增加.

Abstract:

From 1937 5 M_S ≥ 7.0 earthquakes occured along Eastern Kunlun active Fault Zone:M_S 7.5 Huashixia earthquake in 1937, M_S 7. 1 Dulan earthquake in 1963, M_S 7. 3 Mani earthquake in 1973, M_W 7.5 Mani earthquake in 1997 and M_W 7.8 west to Kunlun Mountain Pass earthquake in 2001. The stress transfer and fault activation among large earthquakes in the fault zone, in northern of Tibet plateau, are studied. The Coulomb stress change on the fault plane of subsequent earthquakes produced by seismic dislocation in elastic half space are calculated. The result shows that Coulomb failure stress on the fault plane is increased by the previous earthquake in every events, it is in favor of occurrence of subsequent events, and the calculation indicates that after west to Kunlun Mountain Pass earthquake (M_W 7.8), the Coulomb failure stress in Xidatan -Dongdatan fault segment is significantly increased up to 0. 006~0. 02 MPa, that imply the probability of seismic hazard in this region increased.