用频率域台阵技术推测2001年昆仑山口西大地震的破裂时间与几何特征

Frequency-domain array technique analysis for the rupture duration time and geometrical characteristics of the 2001 Western Kunlun Mountain Pass earthquake

概述频率域远场台阵技术应用于大地震能量辐射源的追踪原理,介绍利用这一技术追踪能量辐射源的一般步骤,并以2001年昆仑山口西大地震为例,分析资料处理中主要参数设置所需要考虑的关键因素.通过分析埃塞俄比亚/肯尼亚地震台阵(EK台阵)的宽频带波形资料,获得了2001年昆仑山口西大地震的起始破裂点的位置,能量辐射源的空间分布特征,以及破裂持续时间.根据EK台阵资料的分析结果,2001年昆仑山口西大地震的起始破裂点位于布喀达坂峰东侧(35.92°N,91.70°E),破裂持续时间不超过160s,破裂长度约520km.其中,初始破裂点以西为180km,以东为340km.断层西段在布喀达坂峰附近向西南方向发生弯曲,与地表破裂吻合.断层东段似乎在西大滩断裂附近向东北方向发生弯曲,其方向与西大滩断层的走向一致,但二者相距约30km.另外,分析结果似乎表明,地震断层的西段近乎直立,而东段逐渐南倾.

In this paper, we briefly describes the principle of tracking energy radiation sources of large earthquakes using frequency-domain far-field array technique, presents general steps of tracking energy radiation sources, and takes the 2001 Western Kunlun Mountain Pass earthquake as an example to analyze key factors for setting parameters while processing data. The location of the rupture initiation point, the spatial characteristics of the energy radiation sources and the rupture duration time of the 2001 Western Kunlun Mountain Pass earthquake are obtained by analyzing broadband waveform data from a seismic array in Ethiopia and Kenya （EK Array）. From the analyzed results, the rupture initiation point of the 2001 Kunlun Mountain earthquake is located in the east of Buka Daban Peak （35.92°N, 91.70°E）, and the rupture duration time is less than 160 s, and the rupture length is about 520 km, with 180 km in the west of the initiation point and 340 km in the east, respectively. The western segment of the earthquake fault bends towards southwest near Buka Daban Peak, which is in concordance with the surface rupture trace. The eastern segment apparently bends towards northeast near Xidatan, which is in agreement with the strike of Xidatan fault, but 30 km away from Xidatan fault. In addition, the analyzed results imply that the western segment of the earthquake fault appears erect while the eastern segment appears to be gradually dipping southwards.