Abstract: The in version method for Lame's parameters λ、μ and dissipative factor γ in the layered earth model is set up by means of the 2-D one order dissipative elastic wave equation in the vector form. Through transformation and decomposition,the inverse problem for λ、μ、γ in the 2-D one order dissipative elastic wave equation in the vector form is changed into the inverse problem for λ、μ、γ in the 1-D one order partial differential system with a free boundary. It is proved the inverse problem is well-posed. So we know that Lame's parameters λ、μ and dissipative factor γ in the layered earth model can be uniquely determined from the particle velocity fields on the line in its surface at all times due to the transverse and longitudinal pulse plane waves simultaneously emitted at normal incidence.

Key words: inverse problem, dissipative factor, Lanle's parameter, elastic wave equation