Locating seismic scatterers at the base of the mantle beneath eastern Tibet with PKIKP precursors  

作　　者：SHEN XuZhang 1,2,3 & ZHOU HuiLan 1 1 Laboratory of Computational Geodynamics,Graduate University of the Chinese Academy of Sciences,Beijing 100049,China 2 Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,China 3 Lanzhou Base of Institute of Earthquake Prediction,China Earthquake Administration,Lanzhou 730000,China 

出　　处：《Chinese Science Bulletin》2010年第8期723-729,共7页

基　　金：supported by the National Natural Science Foundation of China (Grant No.40574024);the Basic R&D Fund of Institute of Earthquake Prediction,China Earthquake Administration (Grant No.2009A19)

摘　　要：Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array.We measured their incident angles,arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techniques.These measurements allowed us to locate the scatterers that generated the observed precursors.We found that the scatterers are located in the lowermost mantle beneath eastern Tibet,which is featured by a high-velocity anomaly based on previous tomographic studies.The high velocity anomaly was interpreted as the slab remnants of the ancient Tethys subduction.We thus speculate that the observed scatterers are either related or induced by the subducted slab.Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array. We measured their incident angles, arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techniques. These measurements allowed us to locate the scatterers that generated the observed precursors. We found that the scatterers are located in the lower- most mantle beneath eastern Tibet, which is featured by a high-velocity anomaly based on previous tomographic studies. The high velocity anomaly was interpreted as the slab remnants of the ancient Tethys subduction. We thus speculate that the observed scatterers are either related or induced by the subducted slab.

关 键 词：地震前兆 西藏东部 下地幔 散射 定位 地震台阵 入射角度 旅行时间 

分 类 号：P315[天文地球—地震学]