Volcanic crises are often associated with magmatic intrusions or
pressurization of magma chambers of various shapes. These volumetric
sources deform 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 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.