关键词: 昆仑山口西8.1级地震, 地震图像, 地震空区, 远场前兆异常

Abstract: Before the M_S 8.1 West Kunlun Mountain Pass earthquake,an orderly evolution of seismicity patterns was observed in the Qinghai-Tibet block:the evolution of seismic gaps showed a time span of several to decades of years and a space span of hundreds to thousands of kilometers,and that of seismic stripes had a time span of several years and a space span of thousands of kilometers.After 1990,the seismic precursory observation networks in Qinghai,Gansu,Sichuan,Xinjiang and Ningxia Provinces and autonomous regions recorded some typical far-field anomalies.These abnormal tendency changes roughly coincided with the formation time of seismogenic gaps and seismic stripes and were distributed in the Qilian Mountains tectonic zone,the East Kunlun tectonic belt,the West Qinling tectonic belt,the north-south tectonic belt and the Tianshan tectonic belt.The far-field anomalies and the spatial-temporal evolution of seismic gaps were complementary and correlated to each other.This article discusses the ordered and phased characteristics in the evolution of the above anomalies with the space-time preparation process of the M_S 8.1 earthquake.

Key words: the M_S 8.1 West Kunlun Mountain Pass earthquake, seismicity pattern, earthquake gap, far-field precursory anomaly