Simulation And Visualization Of Seismic Velocity Field Based On 3-D Crust Model

In the field of crustal structure research,a variety of 3D Crustal Model have been obtained by geophysical methods.However,there are several problems in these models,including multiplicity of solution,resolution difference,depth difference and attribute difference.The above problems restrict the fusion of geological features in diffrient models and the construction of only velocity field model.Moreover,3D crustal model based on geophysical forward modeling and inversion method is a regular grid model which is composed of geophysical properties.The model can not achieve 3D visualization of crustal structure,and can not express the spatial distribution feature and attribute field feature in the internal structure.In order to realize the velocity field fusion of multi-source heterogeneous 3D crustal model and the 3D visualization of velocity field model in crustal structure,a simulation and visualization method of seismic velocity field based on 3D crustal model is provided.The primary research achievement are described below.(1)Based on the co-kriging method,geostatistics principle,correlation of seismic wave and gravity,and the fitting method of 3D variogram function,a fusion method about velocity field of multi-source heterogeneous 3D crustal model is proposed.Fusion velocity field model of crustal structure is established by the fusion method and it is constrained by the geological characteristics of each model.This model integrates the differences of resolution,depth,attribute and structure in 3D crustal models of multi-source heterogeneous.In addition,it can integrate geological feature information of different 3D crustal models.(2)Using Paraview,an open source platform,a 3D modeling method of crustal structure is proposed.Based on the fusion velocity field model of 3D crustal structure,feature extraction method of boundary and velocity field are studied for the main discontinuity surface and velocity anomaly in the crust.This method can obtain the boundary and velocity field information of each stratum.The boundary information is used to simulate the 3D spatial distribution characteristics of the main discontinuity surface and velocity anomaly by the Delaunay triangulation method in the crust.The velocity field information is used to simulate the spatial distribution characteristics of 3D velocity field by the Delaunay tetrahedral partition method in the stratum and the velocity anomaly.Afterwards,the 3D hybrid model of crustal structure is constructed by the 3D model format of VTK,including the boundary model and the field model.(3)The simulation of seismic wave propagation law in seismic velocity field can realize the expression of anisotropic and heterogeneous for 3D velocity field which is used to represent the crustal structure.Propagation law of seismic wave ray in complex 3D crustal structure is studied by seismic ray tracing simulation method,based on programmable script of Python.In the mixed model of 3D crustal structure,ray propagation path simulation of sliding wave and refraction wave is realized and this simulation is applied to express the anisotropy and heterogeneity of velocity field in crustal structure.(4)The Shanxi fault depression zone in the middle of North China Craton was selected as the research area to verify the above methods.Taking this region as an example,a fusion velocity field model of 3D crustal structure was constructed by P-wave velocity structure and S-wave velocity structure.In the end,unified modelling of crustal structure was realized,and the velocity field of crustal structure was simulated and visualized.The result show that the method is feasible and effectiveThe main innovations include the following two?(1)A new method of seismic velocity field fusion is proposed,and the multi-source heterogeneous model integration of 3D crustal different is realized.(2)Based on Paraview,3D modeling and visualization of crustal velocity field are realized.