We are working to unify physical-chemical models of erupting volcanoes with resulting deformation, that can be measured with GPS, InSAR, tiltmeters and other instruments.
Our focus has been on the evolution of an effusive silicic eruption through time, involving the rise of magma from a deep chamber through a conduit to the surface and growth of a lava dome. As the magma rises to the surface its pressure drops and gas bubbles are exsolved from the melt. This, along with the formation of crystals, results in a dramatic increase in the viscosity of the magma, and the formation of a stiff plug of rock which is extruded from the volcano like very hot toothpaste from a tube. Modeling this behavior, and relating it to deformation of the surrounding host rock, requires the solution of a complex system of coupled equations. We have been applying this approach to the 2004-08 eruption of Mount St. Helens, Washington. Mount St. Helens began to erupt in the fall of 2004 with very little precursory seismicity or ground deformation, which gave public officials little time to prepare for a potential eruption. We hope that by better understanding these events we can improve our ability to forecast eruptions at other silicic volcanoes around the world.