利用甘肃地震台网记录的sP前驱波研究汤加—斐济俯冲带“410”间断面深度  

On“410”discontinuity depth of the Tonga-Fiji subduction zone by the sP precursor recorded by Gansu seismic network

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

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》2016年第1期53-58,共6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(41504050)联合资助

摘　　要：本文首先利用甘肃数字测震台网和甘东南野外观测流动台阵记录的汤加—斐济俯冲带深震震相sP,使用倾斜叠加方法有效提取sP在近源区"410"速度间断面底界面反射的弱前驱波s410P;其次基于CRUST1.0修正的IASP91模型,通过震相sP与其前驱波s410P的到时差对比,给出了汤加—斐济俯冲带"410"速度间断面底部反射点的深度约为398.5km,抬升约11.5km,这与俯冲带与近源区"410"间断面的相互作用有关;最后得到了该区域新的地震波速度模型IASP91_Tonga.本文结果将对更好地认识该俯冲带的复杂结构、正确理解地球深部的动力学过程具有重要的参考价值.The sP seismic phase of the Tonga-Fiji subduction zone have a clear image in the Gansu Digital Seismic Network and southeastern Gansu temporary observation array. In this paper, we extracted the weak precursors s410 P by slant stack method, and the s410P precursors are produced by deep focus earth- quakes that result from near-source underside reflection off ＂410＂. We computethe depth of ＂410＂ discontinuity by using the differential travel time between sP and its precursor s410 P near Tonga-Fiji subduction zone based on the modified velocity model （IASP91 Tonga） in this zone based on CRUST1.0 model. The depth of ＂410＂ discontinuity is about 398.5 km, and uplifted about 11.5 km, which maybe relate to the interaction of the subduction zone and the ＂410＂ dis- continuity in the near-source zone. This result is of great significance to recog- nize the complex structure of subduction zones and objectively understand the dynamic process of the deep Earth.

关 键 词：sP震相 前驱波s410P 间断面 俯冲带 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]