Pressure recovery in magma due to bubble growth

Pressure recovery in magma subject to sudden depressurization is investigated in terms of the growth of bubbles containing magmatic volatiles. Assuming conservation of volatile mass and pressure equilibration between the bubbles, melt and a surrounding elastic medium, the final magma pressure is completely determined by its initial pressure and the magnitude of the pressure drop. Simulations show that the initial magma pressure is easily recovered, or even exceeded, when magma containing tiny bubbles is surrounded by a relatively stiff elastic medium under low confining pressure. This result suggests that when processes such as magma withdrawal, dike intrusion, and nearby seismicity decrease the pressure in a magma chamber, magma re-pressurization can occur without new injection of magma.