海底地震仪(OBS)主动源转换横波的应用  

Application of Converted S-Waves from the Active-Source Ocean Bottom Seismometer Experiment

作　　者：张洁[1] 李家彪[1] 阮爱国 卫小冬[1] 牛雄伟[1] 于志腾 庞新明 Zhang Jie;Li Jiabiao;Ruan Aiguo;Wei Xiaodong;Niu Xiongwei;Yu Zhiteng;Pang Xinming(Key Laboratory of Submarine Geosciences,Second Institute of Oceanography,SOA,Hangzhou 310012,China;State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;CAS Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Guangzhou 510301,China)

机构地区：[1]国家海洋局海底科学重点实验室国家海洋局第二海洋研究所,浙江杭州310012 [2]海洋地质国家重点实验室同济大学,上海200092 [3]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,广东广州510301

出　　处：《地球科学》2018年第10期3778-3791,共14页Earth Science

基　　金："全球变化与海气相互作用"专项(No.GASI-GEOGE-01);国家青年科学基金项目(No.41706044);国家海洋局第二海洋研究所基本科研业务费专项(Nos.JG1602;JG1509);国家重大研究计划重点支持项目(Nos.91028006;91228205;91628301;91428204)

摘　　要：横波(S波)为偏振波,具有不同于纵波(P波)的特性,对于地震探测具有特殊的意义.在被动源地震探测中已得到广泛的应用,如接收函数、S波分裂等.在主动源(气枪)海底地震(OBS)探测中,震源在水中,S波为地层转换波,其应用还不多.本文在介绍转换S波的产生、模式、处理和识别的基础上,以实例为切入点简述其具体应用.这些应用主要是基于1D/2D转换S波,用于揭示海底岩石类型、推断地壳性质、共轭陆缘问题、判定地幔蛇纹石化、估算天然气水合物的饱和度和预测流体等.目前在南海已获得了大量的2D和3D的OBS转换S波数据,可将转换S波的研究逐步从2D发展到3D研究,同时结合其他地球物理资料进行共同分析.利用转换S波的研究,有利于揭示南海扩张停止后形成的海山下不同地层的岩性和判定上地幔低速的性质等.Shear waves are polarized waves showing different characteristics from compressional waves,which are specially important to the seismic exploration. They have been widely used in the passive-source seismic studies,such as the receiver functions and shear wave splitting. However the application of shear waves is still limited in the active-source ocean bottom seismometer exploration. Shear waves are converted waves for the underwater seismic source. In this paper,we firstly summarize the conversion,mode type,processes and identification of shear waves. And we also use real examples to introduce different applications in different oceans. The studies of converted shear waves are mainly used to reveal the submarine rock property,infer the crustal type,discuss the conjugate relationship of the continental margin,identify the mantle serpentinization,infer gas hydrate saturation and predict the fluids based on 1 D/2 D converted shear waves. Numerous 2 D/3 D OBS data have been collected in the South China Sea,hence we can gradually change the studies of converted shear waves from 2 D to 3 D and conduct analysis in combination with other geophysical data. Using those data will help to reveal the composition of seamounts and identify the porosity of the low-velocity upper mantle in the South China Sea.

关 键 词：海底地震仪(OBS) 转换横波 纵横波速比 地球物理 

分 类 号：P738[天文地球—海洋地质]