Poroviscoelastic Dynamics of Mushy Magmatic Systems

Historically in volcanology, it was thought that a magmatic system consisted of a simple spherical liquid chamber of magma, surrounded by host rock. However, recent evidence suggests that large volumes of melt are disseminated in crystal mush regions, leading to large trans-crustal mushy-magmatic systems. The presence of a crystal mush has many implications for the characteristics of surface displacements caused by magma movements, such as during an intrusion or eruption. While many previous studies have modelled ground deformation due to magma mobilisation using a simple point source or dislocation model embedded in an elastic half space, few studies have accounted for the existence of mush as a poroelastic or viscoelastic material. 

Current studies suggest that surface deformation can be caused by both poroelastic and viscoelastic deformation of the mush. With our model we account for this behaviour on a poroviscoelastic spectrum demonstrating the significance of this rheology for observations of deformation. We expand on existing poroelastic and viscoelastic models to produce an encompassing poroviscoelastic model that can predict the characteristics of measurable deformation at the Earths surface. In order to do this, we first present a one-dimensional generalised model that describes the behaviour of a poroviscoelastic material. We then adapt this model to a relevant three-dimensional geometries to provide tools for analysing the impact of magma intrusion or eruption for a given system and to provide insight into resulting deformation signals.