Quasi-two-dimensional joint inversion of the data from the controlled source audio-frequency magnetotellurics and the microtremor survey
Both the controlled source audio-frequency magnetotellurics(CSAMT)and the microtremor survey exhibit promising appli-cation prospectsunder strong urban interference.However,single geophysical inversion methods are challenged by a multiplicity of solu-tions.To achieve the complementary advantages of different geophysical methods,and address the lateral discontinuity of single-point inversion,this studyexplored the quasi-two-dimensional joint inversion of the CSAMTand microtremor survey data.It enabled the joint inversionby introducing a lateral constraint matrix into the objective function for joint inversion and employing the limited-memory Broy-den-Fletcher-Goldfarb-Shanno(LBFGS)algorithm.The reliability and effectiveness of the joint inversion were verified using the inver-sion example of synthetic data from theoretical models.The results show that compared to single data inversion,the joint inversion can effectively improve the accuracy of inversion results,with the resistivity model more consistent with theshear-wave velocity structure.Moreover,lateral constraints can effectively reduce the discontinuity of the physical parameters of adjacentsurvey points.The quasi-two-dimensional joint inversion with lateral constraints enhances the inversion reliability by obtaining more reasonable profile results of phys-ical parameters and structures with the efficiency of single-point inversion.
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