On the identification of a transition zone in electrical conductivity between the lithosphere and asthenosphere: a plea for more precise phase data.

An analytical formulation for an arbitrary n-layered earth containing both constant conductivity layers and transitional layers has not been published. Presents a general matrix technique for such a problem in which the solution matrix is built up from n-1 layer connection matrices. This theory is applied to generate the theoretical surface response of two specific models of the lithosphere and asthenosphere. For both models, techniques of linear inverse theory are applied to ascertain if a transitional zone between the lithosphere and asthenosphere could be resolved by surface measurements. It is shown that the impedance phase data is far more important for resolving this model parameter than is the apparent resistivity data.-from Authors