南海巴士海峡三维OBS探测的异常数据恢复  

Abnormal data retrieval of three-dimensional OBS survey at the Bashi Channel area of the South China Sea

作　　者：张佳政[1] 丘学林[1,2] 赵明辉 游庆瑜[3] 贺恩远[1] 王强[1,2] ZHANG JiaZheng1 , QIU XueLin1,3, ZHAO MingHui1 , YOU QingYu2 , HE EnYuan1 , WANG Qiang1,3(1 Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology Chinese Academy of Sciences, Guangzhou 510301, China; 2 Key Laboratory of Petroleum Resources Research, Institute of Gology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; 3 University of Chinese Academy of Sciences, Beijing 100049, Chin)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室中国科学院南海海洋研究所,广州510301 [2]中国科学院大学,北京100049 [3]中国科学院油气资源研究重点实验室中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2018年第4期1529-1538,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(91428204,41606064,41674092,91428205);中国科学院先导专项B(XDB06030202)联合资助

摘　　要：为了探明南海东北部马尼拉俯冲带北段的地壳结构属性,2016年4—6月,"实验2"号科考船执行基金委共享航次,在巴士海峡区域实施三维海底地震仪(OBS)深地震探测实验.实验总共投放48台国产便携式OBS,最终回收41台,放炮测线长2300km,有效放炮10800次,获得了宝贵的第一手数据资料.但初步处理显示,新研发的25台OBS数据异常,未能识别有效震相,给后续计算模拟带来极大困难.为此,本文对异常数据进行了深入分析,通过数据格式检查、导航放炮时间查对、相邻台站信号对比、外部时间和内部时间分析等手段,发现数据异常的原因是采样间隔发生了变化,由设置的4.0ms变为实际的4.5ms,导致内部时间出错,无法正确裁截和对齐震相.新版仪器为节能优化,调低了CPU主频,导致在较高采样率情况下,实际采样间隔比预设要长,这是造成数据异常的主要原因.通过修正采样间隔和数据重采样的方法,我们成功恢复了异常数据,获得了清晰的地震剖面.此项研究不仅挽救了宝贵的地震数据,为下一步地壳结构研究提供数据基础,而且提升了国家基金委共享航次的科学意义,可为今后国产仪器的研发和使用提供重要参考.A three-dimensional seismic survey was carried out in the Bashi Channel area of the South China Sea from April to July 2016 by R/V ＂Shiyan2＂in order to explore the crustal structure of the northern Manila trench subduction zone.Forty-eight Chinese portable OBSs were deployed and finally 41 OBSs were recovered.A total 10,800 shots were fired with shooting lines up to 2300 km long.Abundant seismic data were collected,but those recorded by 25 new types ofChinese OBSs were abnormal.No seismic phases can be identified from these 25 seismic record sections,leading to a serious problem in subsequent structural simulation.After checking data format,verifying shooting time,comparing shooting signals with adjacent normal OBSs,and analyzing the external and internal OBS data file time,we finally found that the sample intervals of abnormal OBSs have been changed from 4.0 ms to 4.5 ms.The OBS internal time was calculated wrong due to the sample interval change,and no seismic phases were identified during data format conversion.Decreasing CPU frequency of the new type OBS in order to save energy is the main reason to change the sample interval.By use of adjusting sample interval and resampling,the abnormal seismic data of 25 OBSs were retrieved eventually and clear seismic phases can be identified in these 25 seismic record sections.This research not only retrieved the valuable OBS data which are the basis for further structural simulation,making the maritime mission of NSFC major project more complete,but also promoted the scientific significance of this cruise and provided an important reference for the development and usage of Chinese OBSs in the future.

关 键 词：异常数据修复 海底地震仪 三维探测 巴士海峡 南海 

分 类 号：P738[天文地球—海洋地质]