收稿日期: 2009-08-06
修回日期: 2009-09-21
网络出版日期: 2011-10-10
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
Received date: 2009-08-06
Revised date: 2009-09-21
Online published: 2011-10-10
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)
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
卫小冬,赵明辉,阮爱国,丘学林,夏少红,朱俊江,黄海波, . 南海中北部OBS2006-3地震剖面中横波的识别与应用[J]. 热带海洋学报, 2010 , 29(5) : 72 -80 . DOI: 10.11978/j.issn.1009-5470.2010.05.072
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.
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