区域重力场变化的场源参数反演方法及在川滇地区的应用

发布时间：2018-06-02 22:16

本文选题：区域重力场变化 + 位场反演　；参考：《中国地震局地球物理研究所》2016年硕士论文

【摘要】：区域重力场变化的场源特征研究是了解地下物质结构与构造运动的基础,是研究地球动力学过程的重要手段,是研究地震孕育与发震机理的关键技术。本文应用区域重力场变化数据,通过反演技术来获取场源特征参数。在现有的重力位场理论模型基础上,选择了欧拉反褶积(Euler deconvolution)方法实现对区域重力场变化数据的反演。首先,本文总结了国内外近几十年欧拉反褶积方法进行的一系列改进措施,分析了欧拉反褶积方法处理的两个关键问题,即构造指数和滑动窗口的选取问题,并讨论了如何解决欧拉解的发散性和稳定性等问题。其次,采用直立圆柱体模型和直六面体模型模拟了重力异常及重力导数异常,发现在异常体边缘重力导数具有比重力本身更高的灵敏度和分辨率,能更好的识别多个异常体。运用常规欧拉反褶积方法、重力垂直导数的欧拉方法、重力水平度的欧拉方法以及解析信号的欧拉方法对单个异常源和组合异常源模型进行模拟,开展对重力变化场源特征的定性和定量研究,能有效地圈定异常源的边界位置并定位深度位置,通过反演获得最佳构造指数和反演参数,在此基础上,用水平梯度滤波方法进行处理获取了较为收敛的欧拉解。最后,对川滇交界地区2012年到2014年连续6期的实测流动重力数据进行处理分析了其空间分布规律,并在模型优选的基础上,尝试将三维欧拉反褶积方法用于川滇交界地区实测流动重力信号的场源位置反演,结合2014年8月3号鲁甸Ms6.5地震的场源分布情况,发现欧拉方法反演的异常源与实际鲁甸地震的发震位置相吻合,都集中在昭通断裂带附近,且深度上也相符合,反演深度主要集中在20±10km。本文研究表明：欧拉反褶积方法能对流动重力信号进行反演和解释,探测地壳内部可能的物质迁移,圈定场源的边界位置和深度位置,为流动重力获得的区域重力场变化信号的反演和解释提供了思路和方法。但欧拉反褶积方法也有其局限性,比如解的稳定性和发散性问题,仍是今后欧拉反褶积方法研究重点和改进的主要方向,这对解决欧拉反褶积方法在重磁位场资料的反演和解释和应中具有重要意义。本文研究内容有助于开展以场求源的地球物理数据解释,能为研究地震孕育过程的介质变化与构造运动等问题提供技术参考。
[Abstract]:The study of the field source characteristics of the regional gravity field is the basis of understanding the structure and tectonic movement of underground materials, the important means of studying the geodynamic process, and the key technology of studying the seismogenic and seismogenic mechanism. In this paper, the data of regional gravity field variation are used to obtain the characteristic parameters of the field source by inversion technique. Euler deconvolution (Euler deconvolution) method is used to invert the regional gravity field variation data on the basis of the existing gravitational potential field theory model. Firstly, this paper summarizes a series of improvement measures of Euler deconvolution method in recent decades at home and abroad, and analyzes two key problems of Euler deconvolution method, that is, the selection of structural index and sliding window. How to solve the divergence and stability of Euler solution is discussed. Secondly, the vertical cylinder model and the straight hexahedron model are used to simulate the gravity anomaly and the gravity derivative anomaly. It is found that the gravity derivative has higher sensitivity and resolution than gravity itself, and it can better identify multiple abnormal bodies. Using the conventional Euler deconvolution method, the Euler method of vertical derivative of gravity, the Euler method of gravity flatness and the Euler method of analytic signal, the model of single anomaly source and combined anomaly source is simulated. The qualitative and quantitative study of the source characteristics of gravity variation field can effectively delineate the boundary position of the anomalous source and locate the depth position, and obtain the best structural index and inversion parameters by inversion. The convergent Euler solution is obtained by using horizontal gradient filtering method. Finally, the spatial distribution of the measured flow gravity data from 2012 to 2014 in the Sichuan-Yunnan border area is analyzed, and the spatial distribution of the data is analyzed based on the optimal selection of the model. The 3-D Euler deconvolution method is applied to the inversion of the field source position of the measured flow gravity signals in the Sichuan-Yunnan border area, and combined with the field source distribution of the Ludian Ms6.5 earthquake on August 3, 2014. It is found that the anomalous source inversion by Euler method is consistent with that of the actual Ludian earthquake, which is mainly located near the Zhaotong fault zone and in depth, and the inversion depth is mainly 20 卤10km. The results show that the Euler deconvolution method can invert and interpret the flow gravity signal, detect the possible material migration in the crust, and delineate the boundary and depth position of the field source. It provides a method for inversion and interpretation of regional gravity field variation signal obtained by flow gravity. However, the Euler deconvolution method also has its limitations, such as the stability and divergence of solutions, which is the main research focus and improvement direction of Euler deconvolution method in the future. This is of great significance to the solution of Euler deconvolution in inversion, interpretation and application of gravity and magnetic field data. The research in this paper is helpful to the interpretation of geophysical data derived from the field and can provide a technical reference for the study of the medium change and tectonic movement during the earthquake preparation process.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P315.726

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