The manual and model included in this repository outline the steps to set the initial state of stress and pore pressureregime in a dynamic magma-mush (DMM) reservoir and the surrounding crust in COMSOL Multiphysics® v6.1, so that they are both at equilibrium with gravitational forces when the simulation starts. The DMM reservoir is modelled as a poroelastic inclusion in a linear-elastic crust, fully saturated with a single-phase melt. Two-dimensional axisymmetric domains are considered, although the procedure can be easily applied to three-dimensional settings.