核幔界面衍射波P_(diff)震相最大记录震中距探讨  

A discussion on the largest recorded epicentral distance for seismic phase P_(diff) diffracted on core-mantle boundary

作　　者：秦满忠[1,2] 李顺成[3] 刘旭宙[1,2] 张淑珍[1] 张元生[1,2] 

机构地区：[1]中国地震局兰州地震研究所,中国兰州730000 [2]中国地震局地震预测研究所兰州科技创新基地,中国兰州730000 [3]中国地震局地质研究所地震动力学国家重点实验室,中国北京100029

出　　处：《地震学报》2015年第2期249-256,共8页Acta Seismologica Sinica

基　　金：中国地震局地震预测研究所基本科研业务专项(2012IESLZ09);国家自然科学基金项目(40874029)共同资助

摘　　要：智利MS8.8特大地震在甘肃数字测震台网记录的最大震中距达179.7°,通过读取该地震初至震相的观测走时,计算该震相的平均观测慢度为4.104s/°,与Pdiff震相的理论慢度4.439s/°基本一致.研究结果表明:由于甘肃数字测震台网和甘东南野外观测流动台阵独特的地理位置,记录到了至今全球最大震中距(179.7°)的核幔界面衍射波Pdiff震相;Pdiff震相起始观测走时明显滞后于IASP91理论走时;核幔界面复杂的形态对不同方位传播的Pdiff震相观测走时产生了一定的影响.The largest epicentral distance of Chile MS 8.8 earthquake reaches 179.7°recorded by Gansu Digital Seismic Network.Through artificially reading observational first-arrival travel time of the Chile earthquake,we calculated the average observational slowness of the first arrival phase is 4.104 s/°,which is basically consistent with theoretical slowness （4.439 s/°）of Pdif .The results show that the Pdif can recorded at the epicentral distance 179.7°due to particu-lar location of Gansu Digital Seismic Network and southeastern Gansu tempora-ry observation array;the origin observed travel time lags behind the IASP91 theoretical travel time obviously;and Pdif travel times observed from different directions are affected by complex morphology of the core-mantle boundary.

关 键 词：Pdif 震相 慢度 观测走时 智利 甘肃数字测震台网 甘东南野外观测流动台阵 

分 类 号：P315.63[天文地球—地震学]