Abstract：We present an iterative algorithm for inversely deriving the interval velocity,in- terval density and curved interface depth from gravimetric and seismic data in lay ered medium.The joint inversion problem of gravimetric and seismic data in layered medium can be converted into an optimization problem by introducing a weighted least square objective functional.In order to get the optimal solution of an inverse problem,we analyse systematically the double perturbation processing technique, the first order Born's approximate solution of wave field perturbation and the per- turbation solution of theoretical gravity anomaly in layered medium.Gradient opera- tor formula is obtained using Tarantola's inversion theory.By adopting the steepest descent means ,we develop an optimal algorithm,namely an iterative inversion algo- rithm which is similar to that in seismic migration and spatial back projection.Theo- retical joint inversion of gravimetric and seismic data indicates that this method can decrease unknown parameters,speed up convergence and reduce indeterminacy in in- version.It is really a feasible multiparameter inversion method.
