Inversion Of The Crustal Thickness Of China And Its Adjacent Regions Based On Gravity Observation

Moho lies between crust and mantle as a global interface of the earth.The depth of Moho,as well as called crust thickness,is one of the focus researches of the geophysical field.Many domestic and foreign scholars are devoted to get more accurate results of the crust thickness.There are some inversion methods and global crustal models of crustal thickness.Commonly,first step of the process is to extract disturbance information of Moho.Then crustal thickness is obtained using a formula of single interface inversion.Obtaining the disturbance information need to get through the calculation of stripping the gravity disturbance step by step.The topographic correction had the greatest influence on the result of crustal thickness.The small scale topographic correction can be regarded as a plane,mainly using the prism to finish quality reduction.But for a wide range or the topographic correction in the global range,it must be considered that the influence of the curvature of the earth.There are some researches based on the problems below in this thesis.1.In order to solve the problem of spherical curvature errors for topography correction in the large area,it can better fit the terrain that using Tesseroid model.The spherical harmonic spectrum formula in the spherical coordinate is expanded to cubic term of approximate calculation.In this thesis,Newton's integral formula is expressed in polar coordinate instead of the spherical coordinate.The method is fully accurate expression and can be strictly converted in spherical coordinates as the advantage.The method avoids the topography reconstruction,selecting the scale of 0°~60°N,60°~150°E as the China and its adjacent area for experimental verification.2.The inversion of crust thickness belongs to the category of the layer inversion and a kind of inversion problem of gravity.Many experts and scholars have done in-depth research on layer inversion.And some inversion formulas are given in this paper.In this paper adopted the formula in the spatial domain to inverse China and its adjacent area of the earth's crust thickness.The form is relatively simple,improving the computational efficiency.The range of China and its adjacent area is 0°~60°N,60°~150°E.And we compare and analyze the results with that of GEMMA Moho model.