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.Recent viscoelastic models of volcano deformation have used the Arrhenius formulation (see section 3.3.3) to estimate the viscosities of the medium (e.g., Gregg et al., 2012;Hickey et al., 2015), employing commonly used variables within the formulation that are potentially representative of the composition and temperatures of the subsurface, without full exploration of their potential values. Understanding the possible variations within these parameters along with their implications is critical to depict realistic rheological scenarios. It is also crucial for future studies that aim to understand crustal deformation, magma reservoir failure, intrusion propagation, and eruption forecasting.