Analytical Solutions for Gravity Changes Caused by Triaxial Volumetric Sources

Volcanic crises are often associated with magmatic intrusions or the pressurization of magma chambers of various shapes. These volumetric sources deform the country rocks, changing their density, and cause surface 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 analytical solutions and computer codes for the gravity changes caused by triaxial sources of expansion. This establishes 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.