未知OBS水平方位的SKS分裂参数测量  

SKS splitting measurements with unknown horizontal orientation of the ocean bottom seismograph

作　　者：司少坤 刘保华 刘晨光[2] 杨挺[3] 封志兵[1,4] 

机构地区：[1]国家深海基地管理中心,青岛266237 [2]国家海洋局第一海洋研究所,青岛266061 [3]同济大学海洋地质国家重点实验室,上海200092 [4]中国海洋大学,青岛266100

出　　处：《地球物理学报》2017年第3期999-1006,共8页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41504045;91128209);中国博士后科学基金(2015M582050)资助

摘　　要：宽频带海底地震仪(OBS)探测是研究海底深部结构最有效的地球物理方法,其中SKS分裂参数测量已被广泛应用于上地幔各向异性的研究.传统的SKS分裂参数测量需要知道确切的OBS水平分量方位,然而OBS的投放过程是自由式的,其两个水平分量在海底的方位是不确定的.本文通过SKS快慢波的运动学特性,发展了一种在未知OBS水平分量方位的情况下直接求取SKS分裂参数的方法,分别用合成地震图和实际观测到的远震资料对该方法进行了数值检验,表明其是一种有效的获得SKS分裂参数的方法,而且相比于传统的先确定OBS水平分量方位,再进行SKS分裂的方法,此方法能够同时获得SKS分裂参数和OBS水平分量方位,应用简便,且减少了累积误差,获得的SKS分裂参数可靠性更高.Broadband ocean-bottom seismograph （OBS） detection technology has become an effective geophysical way for studying the structure and dynamics of the oceanic crust and mantle. The measurement of SKS splitting parameters has been widely used for the study of anisotropy in the upper mantle. It is necessary to know the orientation of the OBS in traditional SKS splitting measurement. However, during typical OBS deployments, sensors are settled onto the seafloor through a free-fall process, leading to unknown horizontal orientation of the OBS sensors. In this paper, according to the kinetic characteristic between last and slow wave, we develop a novel method for SKS splitting measurement with unknown horizontal orientation of the OBS. We test the method with the synthetic waveforms and real teleseismic data, respectively. Model tests show that the method is reliable for SKS splitting measurement. Relative to the traditional method of determining the orientation of the OBS first and then measuring the SKS splitting parameters, this method could get both of them at the same time, which reduces the accumulative errors in traditional method. Its application to the observational data indicates that the method in this paper is effective in SKS splitting measurement with higher reliability.

关 键 词：SKS分裂 各向异性 OBS水平分量方位 

分 类 号：P631[天文地球—地质矿产勘探]