Dual reservoir structure at Soufrière Hills Volcano inferred from continuous GPS observations and heterogeneous elastic modeling

Most inversions of geodetic data for volcanic systems assume homogeneous media. Here we examine the effect of inhomogeneous media using axisymmetric finite element models of Soufrière Hills Volcano (SHV), to show that homogeneous elastic crustal models underestimate both the depth and excess pressure of the deformation source. Continuous GPS data from 1999 to 2009 are then used to infer that the SHV system has multiple crustal pressure sources. For a dual reservoir volcanic model, a deep reservoir located within the mid crust undergoes volume changes approximately an order of magnitude larger than those of the shallow reservoir.