热带海洋学报 ›› 2010, Vol. 29 ›› Issue (5): 72-80.doi: 10.11978/j.issn.1009-5470.2010.05.072

• 海洋地球物理学 • 上一篇    下一篇

南海中北部OBS2006-3地震剖面中横波的识别与应用

卫小冬1 ,3, 赵明辉1, 阮爱国2, 丘学林1, 夏少红1, 朱俊江1, 黄海波1 ,3   

  1. 1. 中国科学院边缘海地质重点实验室, 南海海洋研究所, 广东 广州510301; 2. 国家海洋局第二海洋研究所 浙江 杭州310012; 3. 中国科学院研究生院, 北京100049
  • 收稿日期:2009-08-06 修回日期:2009-09-21 出版日期:2010-10-30 发布日期:2011-10-10
  • 通讯作者: 赵明辉(1967—), 女, 辽宁省锦州市人, 副研究员, 主要从事海洋地球物理研究。
  • 作者简介:卫小冬(1984—), 男, 河南省新安县人, 硕士研究生, 主要从事海洋地球物理研究。E-mail: richild@126.com
  • 基金资助:

    科技部“973”项目(2007CB411701); 国家自然科学基金(40876035; 40776025); 中国科学院南海海洋研究所领域前沿项目
    (LYQY200704); 广东省自然科学基金(07004190); 中国科学院知识创新工程(KZCX2-YW-Q05-04)

Identification and application of shear waves along the profile OBS2006-3 in the mid-northern South China Sea

WEI Xiao-dong1,3, ZHAO Ming-hui1, RUAN Ai-guo2, QIU Xue-lin1, XIA Shao-hong1, ZHU Jun-jiang1, HUANG Hai-bo1,3   

  1. 1. Key Laboratory of Marginal Sea Geology of CAS, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; 2. Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China; 3. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2009-08-06 Revised:2009-09-21 Online:2010-10-30 Published:2011-10-10
  • Contact: 赵明辉(1967—), 女, 辽宁省锦州市人, 副研究员, 主要从事海洋地球物理研究。
  • About author:卫小冬(1984—), 男, 河南省新安县人, 硕士研究生, 主要从事海洋地球物理研究。E-mail: richild@126.com
  • Supported by:

    科技部“973”项目(2007CB411701); 国家自然科学基金(40876035; 40776025); 中国科学院南海海洋研究所领域前沿项目
    (LYQY200704); 广东省自然科学基金(07004190); 中国科学院知识创新工程(KZCX2-YW-Q05-04)

摘要:

 纵横波联合探测可以获得丰富的地下结构信息。纵横波速比和岩石泊松比在预测岩石圈的岩性、物性等介质属性方面有重要的作用。通过对比南海中北部OBS2006-3地震剖面垂直分量和径向分量上的纵横波走时、视速度以及质点运动轨迹, 识别出了转换横波震相。本文以OBS8和OBS10台站的数据为例, 说明了横波识别的方法, 并在拟合好的P波速度模型基础上, 利用RayInvr软件对转换横波震相进行了射线追踪, 确认了PwSs3、PgSs3、PmS等几组转换震相, 计算了这两个站位下的波速比和泊松比。根据OBS2006-3测线下地壳高速层的P波速度(VP=7.20—7.25 km•s−1)、S波速度(VS=4.20—4.23 km•s−1)、泊松比(0.24)等参数, 初步推断下地壳高速层是由上地幔岩浆底侵作用形成。

关键词: 海底地震仪(OBS), 转换横波, 纵横波速比, 南海中北部

Abstract:

Applying the joint exploration of P-wave and S-wave, the complex subsurface crustal structure can be obtained. The association of P-wave velocity and S-wave velocity is very sensitive to the physical state of rocks, and is thus very useful in lithological studies. Compared with travel-time of P-wave and S-wave, apparent velocity and particle’s moving trajectory in vertical-component and radical-component seismic sections, converted S-wave phases were identified in OBS8 and OBS10 along the profile OBS2006-3 in the mid-northern South China Sea. In this paper, taking these two OBSs as examples, we discussed identification and analysis of converted S-waves in detail. A few of S-wave seismic phases (e.g., PwSs3, PgSs3, PmS) were identified based on the optimum P-wave model using the software Rayinvr and the ratio of Vp/Vs and Poisson’s ratio are calculated beneath these two OBSs stations. Based on P-wave velocity (VP=7.20?7.25km•s−1), S-wave velocity (VS= 4.20?4.23km•s−1) and Poisson’s ratio (0.24), we suggest that the high velocity layer in the lower crust has a mafic composition that may originate from magmatic underplating.

Key words: ocean bottom seismometer (OBS), converted S-wave, VP/VS ratio, the mid-northern South China Sea