Genetic Algorithms In Seismic Waveform Inversion And Calculus-based Algorithms In Traveltime Inversion And Their Applications In Seismic Wide-angle Reflection And Refraction Data

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...