Abstract

Volcanic crises are often associated with magmatic intrusions or pressurization of magma chambers of various shapes. These volumetric deformation sources dilate the country rocks changing their density, and cause uplift. Both the net mass of intruding magmatic fluids and these deformation effects contribute to surface gravity changes. Thus, to estimate the intrusion mass from gravity changes the deformation effects must be accounted for. We develop point-source analytical solutions and computer codes for the gravity changes caused by triaxial sources of expansion. This establishes fully coupled solutions for joint inversions of deformation and gravity changes. Such inversions can constrain both the intrusion mass and the deformation source parameters more accurately. In the absence of vertical displacement data, gravity changes together with horizontal displacements can be inverted to retrieve both the intrusion mass and the deformation source parameters.