Programs to compute deformation due to a magma intrusion in elastic-gravitational layered earth models

In previous papers from two of the authors, models, programs and results of programs developed to compute displacements due to volcanic loading with different assumptions have been published. In this paper, these previous models are extended in a set of programs written in FORTRAN 77. These codes allow us to calculate displacements (horizontal and vertical), tilt, vertical strain and potential and gravity changes on the surface of an elastic-gravitational layered Earth model, due to a magmatic intrusion. The intrusion is treated as a point source and the medium can consist of up to four layers overlying a homogeneous half-space. A topmost water layer can be included to calculate sea level changes. We describe the theoretical formulation of the deformation model together with the numerical programs developed. Examples of calculation for the different effects are presented. (C) 1997 Elsevier Science Ltd.