Shirzaei et al. (2011) present Envisat radar InSAR images from 2003 through to 2008. The authors show “a lateral extension of the volcano at the relative rate of as much as ∼6 mm/yr accompanied by subsidence at the rate of as much as ∼5 mm/yr at the volcano summit. We find that lateral motion of the east flank is more significant than that of the west flank”.
The authors interpret the deformation data as “long-term, slow, gravity-driven deformation, possibly in the form of gravitational spreading”.
Shirzaei et al. (2012) extends the Envistat dataset to 2010 and “detect a transient flank failure in the form of landslide at Damavand that is followed by elevated fumarolic activity”. They infer  that the landslide might have triggered volcanic unrest. 
Yazdanparast & Vosooghi (2014) present GPS data from Iranian Permanent GPS Network for Geodynamics (IPGN) to show that deformation reaches a maximum height variation of 4.7 mm and suggest that sill-like source model is the best fit source model.