【作者】 王夫运；

【导师】 张先康；

【作者基本信息】 中国地震局地球物理研究所 ， 固体地球物理学， 2005， 博士

【摘要】 本文系统地研究了地震体波波形数据遗传反演的理论和方法,将遗传算法和Kennett体波理论地震图算法结合,提出新的地震体波波形反演算法,进行了数值检验,并用于达日—兰州—靖边深地震测深部分人工爆破地震记录波形的反演,结合波形正演拟合得到了青藏高原东北部典型地块的地壳精细结构。引进了利用深地震测深走时数据同时反演二维地壳结构和构造的Rayinvr算法,讨论了算法应用一些值得注意的事项和经验,提出算法需进行速度和深度参数归一化及反演参数改正量限制的改进建议,在准葛尔、长白山、华北和燕山盆山耦合区、青藏高原东北缘等地深地震测深走时数据反演中得到较好的应用。 本文的主要工作如下: 系统回顾了深地震测深的主要进展。观测仪器已由传统的模拟仪发展到专门的数字化地震仪采集系统。如DAS—1新型数字化地震采集系统,具有动态范围大,信号记录频带宽的特点,设计多种工作方式,即可用于人工地震数据采集,也可用于天然地震观测。观测系统已从满足二维、区域地壳结构研究要求发展到满足三维、上地幔结构和精细地壳结构研究要求的三维、超长排列超长剖面和高分辨地震折射观测系统。全新的数据库技术的应用使得地震宽角反射折射数据的交换、共享和长期保存、资料的重复利用以及面向数据库的资料解释程序的共享可以更方便快捷地实现。基于波动方程高频近似的二维复杂介质中射线追踪解和程函方程有限插分解及其算法,为深地震测深走时数据反演提供了理论基础和反演的实现。全球范围内大陆地壳结构探测表明,大陆地壳呈现明显的横向不均匀性和分区特征。简要回顾了我国深地震测深的发展和取得的重要成果。 分析了地震宽角反射所射走时数据的特点。回顾了走时数据解释从定性到定量、从一维到二维乃至三维的发展过程,以及各种解释方法的基本原理和优缺点。认为走时数据解释方法应进一步发展反演算法,正演计算宜采用较为稳定有效的有限差分时间场算法,并尽可能引进地震波振幅信息,反演计算宜采用全局优化算法。 分析了地震宽角反射/折射波形数据的特点及其获得地壳细结构的重要作用。回顾了利用波形数据获得地壳结构的方法的发展。认为尽管地震波形数据受影响的因素较多,难以综合模拟,但是波形反演作为一种解释方法,具有不可替代的重要理论价值和实用价值。如天然地震远震体波波形的接收函数反演方法,在揭示地壳上地幔精细结构方面已经取得了巨大成功。 简要总结了青藏高原东北部和华北及首都圈地区地壳结构的研究。已有的地球物理深部探测揭示出,青藏高原东北部地壳厚度较大,达50～60km;地壳平均速度低,6.0～6.1km/s之间;中下地壳普遍表现为强反射性,可能是由地幔热物质上涌侵位和下地壳长期流变作用的结果;重大地块边界地壳和上地幔结构构造变化剧烈。首都圈地区地壳结构和地表地质构造密切相关,华北盆地内地壳厚度小、平均速度低,太行山和燕山地区地壳厚度大、平均速度高;张渤构造带的地壳深部结构构造变化强烈。 详细研究了非线性全局优化非数值算法—遗传算法和广义反射/透射理论地震图算法。遗传算法利用模型空间中一组初始模型而非单个初始模型,模型参数的二进制编码和所有模型参数的编码的字符串而非模型参数值本身,通过初始模型字符串之间的随机的交换、变异和再生的运算及叠代而模型参数本身的非确定性的运算,仅利用目标函数值而不需知道其偏微商信息,从而有效地使初始模型群体稳定地达到总体最优。Kennett广义反射/透射理论地震图算法能够精确模拟薄互层结构中波的传播;震源和接收点可以有不同的结构,能同时模拟震源—结构响应和接收点—结构响应;引进复地震速度,把介质非弹性(衰减)因素包含在内;广义反射透射系数矩阵确保了数值计算的精度;可以计算介质的完全响应,也可合成任更多还原

【Abstract】 In this paper, the seismic body waveform inversion is systematically studied, a new method for seismic body waveform inversion is presented by combination of Kennett seismogram and Genetic algorithm. The inversion algorithm is tested with synthetic data typical of crustal seismic experiments to (1) study that it recovers the true model in several idealized cases, (2) understand the effects of different Genetic algorithm parameters, (3) study its convergence behaviour and sensitivity. Inversions with modeling of refraction and reflection waveform from the Dari— Lanzhou—Jingbian Deep Seismic Sounding experiment reveales images on fine crustal structure at northeasten region of the Qinghai-Xizang plateau. A new method of seismic traveltime inversion for simultaneous determination of 2-D velocity and interface structure is developed that is applicable to Deep Seismic Sounding data. The methodology and practical consideration necessary for handling real data is discussed, the improvements on model parameter normalization and control of model parameter adjustment value for the algorithm is presented. The inversion method is well applied to the seismic wide-angle reflection and refraction data acquired at Zhungeer’s basin, Changbai’s mountain and the region between the north of Huabei’s basin and the south of Yan mountain.The major studies are as follows:The basic developments of the seismic wide-angle reflection and refraction profile are reviewed, (l)digital seismograph nearly substitutes for analogue seismograph. For example, DAS-1 digital seismograph specialized for seismic wide-angle reflection and refraction experiment is widely used. It is characterized by large dynamic measurement range, wide frequency band, different working ways, and is used to observe seismic wave excited by not only explosion but also earthquake. (2)The seismic observation geometry of 3D and super-long profile for studying 3D crustal and upper mantle structure is well used. (3)Applications of database technology to seismic wide-angle reflection and refraction profile conveniently bring about data share, data commutation, data access, data repeated process, and share of object-to-database data processing programs. (4)The ray theory based on approximate high-frequency solution of elastodynamic equations and finite-difference solution of eikonal equation in inhomogeneous media lay a foundation of the inversion of seismic traveltime data. (5)the crustal structure probe in world reveals that the continental crust is characterized by lateral inhomogeneity and blacks in structure. The developments and major results on Deep Seismic Sounding in China are briefly reviewed.The characteristic of seismic wide-angle reflection and refraction traveltime data are analyzed. The development, fundamentals, advantage and disadvantage of the different interpretation methods on traveltime data are expounded in detail. We think that the interpretation of traveltime data are made further advances on inversion, it would be best if forward modeling could use finite-difference algorithm of traveltime field, and inversion could use global algorithm.The characteristic effect on determining the fine crustal structure of seismic wide-angle reflection and refraction waveform data are discussed. Although it is very difficult to inverting waveform data on a suitable match between the observed and synthetic waveform, yet it is very of更多还原