| 秦岭及周边地区瑞雷波方位各向异性 |
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| 引用本文： | 李爽,冯梅,安美建,董树文.秦岭及周边地区瑞雷波方位各向异性[J].地震学报,2014,36(4):531-545. |
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| 作者姓名： | 李爽 冯梅 安美建 董树文 |
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| 作者单位： | 1.中国北京 100081 中国地质科学院地质力学研究所 |
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| 基金项目： | 中国地质调查工作项目“中央造山带与南北构造带交汇区地壳深部地质调查”;国家深部探测技术与实验研究专项(SinoProbe-08);国家自然基金(41174039)共同资助 |
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| 摘 要： | 除了使用前人提取的面波频散曲线外， 还从秦岭及周边地区布设的59个宽频流动地震台的数据和中国地震局及各省局台网的数据中筛选出的地震事件波形和台站间噪声互相关格林函数中提取瑞雷波群速度频散曲线. 利用二维面波层析成像反演获得了瑞雷波周期为10—50 s的各向同性群速度及方位各向异性分布. 结果显示: 周期为10 s的各向同性群速度和方位各向异性分布与各构造单元存在明显的对应关系； 周期为10—50 s的面波在四川盆地和鄂尔多斯盆地内的快波方向多为近NS向. 与前人研究结果不同的是， 本文得到的秦岭、 大巴山构造带周期为10—50 s的面波快波方向均与山脉走向近似平行， 且与SKS波分析得到的快波方向一致. 这表明秦岭和大巴山之下整个岩石圈的快波方向都与山脉走向平行， 预示着秦岭和大巴山整个地壳， 甚至岩石圈发生了类似的变形. 由于四川盆地和鄂尔多斯盆地面波快波方向与SKS波结果差别较大， 推测青藏高原隆升扩展对这两个盆地的地壳基本无影响， 但对其岩石圈上地幔却产生了重大影响.
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| 关 键 词： | 瑞雷波 群速度 方位各向异性 地壳 秦岭 |
| 收稿时间： | 2013-09-22 |
Azimuthal anisotropy of Rayleigh wave in Qinling and its adjacent areas |
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| Institution: | 1.Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China2.Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | We retrieved Rayleigh-wave group velocity dispersion from earthquake waveforms and inter-station Green’s functions cross-correlated from noises recorded by our 59 portable broadband seismic stations and hundreds of national and provincial stations of China Earthquake Administration in Qinling and its adjacent areas. Using the dispersion data and the previously published Rayleigh wave dispersions, we invert for isotropic group velocities and azimuthal anisotropies beneath Qinling and its adjacent areas for the periods of 10—50 s by 2-D surface wave tomography. The results show that the distribution of isotropic group velocities and the azimuthal anisotropies in the period of 10 s is obviously correlated with the crustal tectonics in the entire study region. The fast-propagation direction for the Rayleigh waves in the periods of 10—50 s beneath the Sichuan and Ordos basins are mostly near N-S. Unlike previous studies, the fast direction for all the periods from 10 s to 50 s beneath Qinling and Daba mountains and adjacent areas is near E-W which is nearly parallel to the strike of the regional tectonics. The fast-propagation direction from surface waves are consistent with that by previous SKS splitting analyses beneath the Qinling and Daba mountains, indicating that the deformation at the depths of the whole crust beneath the Qinling and Daba mountains are similar, even down to the lithospheric base. However, the Rayleigh wave fast-propagation directions beneath Sichuan and Ordos basins are different from fast-wave directions inferred from previous SKS analyses, indicating that the uplifting and extending of Tibetan Plateau did not reform the crust but the lithospheric upper mantle beneath the two basins. |
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