| 美国中东部地震台阵波场的三分量波形梯度 |
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| 引用本文： | 周鲁,梁春涛,杨宜海.美国中东部地震台阵波场的三分量波形梯度[J].地球物理学报,2017,60(9):3352-3367. |
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| 作者姓名： | 周鲁 梁春涛 杨宜海 |
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| 作者单位： | 1. 地质灾害防治与地质环境保护国家重点实验室(成都理工大学), 成都 610059;2. 地球勘探与信息技术教育部重点实验室(成都理工大学), 成都 610059 |
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| 基金项目： | 国家自然科学基金（41374058，41674059，41340009）联合资助. |
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| 摘 要： | 波形梯度法是一种全新的台阵数据处理技术,该方法利用子台阵中的波形差异可以得到一些基本的地震波传播参数.本文首次将其应用于美国中东部地震台阵面波的三分量研究当中.首先通过垂向分量的面波进行波形梯度分析,得到垂直分量面波的相速度、传播方向、几何扩散和辐射花样.再通过垂向分量得到的传播方向进行坐标旋转,从而得到了径向分量以及切向分量的面波,再将其应用于波形梯度分析,分别得到径向分量以及切向分量面波的相速度、传播方向、几何扩散和辐射花样.利用2012年8月27日发生在中美洲西海岸地震事件的三分量地震数据的面波波形得到的结果显示,在相同周期,研究区域的三个分量面波的相速度分布横向差异显著.切向分量面波的相速度分布特征差异较大,可能是由于径向各向异性造成的.三个分量的传播方向变化都不大,且切向分量的传播方向变化大于垂直分量与径向分量,说明地震波的切线分量在传播过程中受到的影响更大,同时还可以看出传播方向的变化呈现出条带状的特征.几何扩散和辐射花样都是与地震波的振幅项有关的信息,三个分量的几何扩散特征基本一致.但是由于切向分量传播方向变化相对较大,可能导致了切向分量面波的辐射花样有所差异.
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| 关 键 词： | 三分量波形梯度法 相速度 传播方向 几何扩散 辐射花样 |
| 收稿时间： | 2016-10-08 |
Application of three-component seismic-wave gradiometry for the Central and Eastern United States |
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| ZHOU Lu,LIANG Chun-Tao,YANG Yi-Hai.Application of three-component seismic-wave gradiometry for the Central and Eastern United States[J].Chinese Journal of Geophysics,2017,60(9):3352-3367. |
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| Authors: | ZHOU Lu LIANG Chun-Tao YANG Yi-Hai |
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| Institution: | 1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology), Chengdu 610059, China;2. Key Laboratory of Earth Exploration and Information Technology of Ministry of Education(Chengdu University of Technology), Chengdu 610059, China |
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| Abstract: | Seismic-wave gradiometry is a new array data processing technique which uses the spatial variation captured by subarray stations to extract fundamental wave propagation characteristics. We use Seismic-wave gradiometry method for three-component seismic data obtained by USArray TA stations in the Central and Eastern United States. Firstly, we use the Seismic-wave gradiometry to extract phase velocity, wave directionality, geometrical spreading, and radiation pattern by vertical component surface-wave data. Then the original data are rotated to obtain radial and tangential component seismic record utilizing the wave directionality obtained from vertical component surface-wave data. Same as the process for vertical components, we can obtain phase velocity, wave directionality, geometrical spreading, and radiation pattern from radial and tangential component surface-wave data, respectively. The event occurred in the coast of Central-America on 27th August 2012 with a moment magnitude of 7.4. Our results show that the spatial distribution of phase velocity in study area is significantly different. The phase velocity map obtained from tangential component surface-wave data is quite different from that obtained from the vertical components. It may indicate that the medium is transversely isotropic in study area. Wave directionality variations are generally small for all three components, and the wave directionality variations obtained from the tangential component seismogram are slightly greater than other two components in most area. The stripe-patterned distribution appears to be roughly parallel to the ray path direction. Geometrical spreading and radiation pattern are related with seismic-wave amplitude. The primary features of geometrical spreading are consistent among all three-components. Because of wave directionality variations of tangential component are slightly greater than others, the radiation pattern of tangential component also shows differences from other two components. |
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| Keywords: | Three-component seismic-wave gradiometry Phase velocity Azimuthal variations Geometrical spreading Radiation pattern |
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