Impact of Crustal Rheology on Temperature-Dependent Viscoelastic Models of Volcano Deformation: Application to Taal Volcano, Philippines

Abstract

We use ALOS-1 interferometric synthetic aperture radar data spanning the period of 2007–2011 to obtain time-dependent ground deformation data over Taal caldera related to the 2010–2011 volcanic unrest, which did not lead to an eruption. We employ finite element models that account for subsurface thermomechanical properties to test for viscoelastic deformation. We also examine the variability of crustal rheological parameters of the temperature-dependent Arrhenius formulation for viscosity, to investigate the effects on surface deformation. Deformation at Taal is observed to be time dependent and explained by a linear rate of pressure increase in a shallow magma reservoir at 5-km depth within a hot and viscoelastic upper crust. The best-fitting rheological properties of the local setting are consistent with either a felsic or hydrothermally altered uppermost crust. We show the significantly different effects that the variation of rheological parameters has on surface deformation, highlighting the importance of incorporation into future studies of deformation at different volcanic settings.