Regional Model to Estimate Vertical Deformations Due to Loading Seasonal Changes

Abstract

Surface mass transfer produces changes in the terrestrial geometric reference frame that are clearly detectable by GNSS techniques. These deformations are mainly observed in the vertical coordinate component and show periodic behavior with seasonal cycles. Therefore, the assumption that the kinematics of the reference frame has a linear behavior is no longer sufficient.This study focuses on a model of crustal vertical deformations caused by surface loading variations in the South American region. Thirty-four locations were analyzed in order to adjust a parametric exponential function that relates height changes with mass pressure variations.This parametric function depends on regional rheological properties. Crustal deformations were characterized using multi-annual GPS time series provided by SIRGAS and the surface loading information was derived from GRACE spherical harmonic coefficients provided by GRGS (Release 2). The proposed parametric model was able to properly reproduce inter-annual variations observed in vertical displacement in a 9-year time-span (2003–2012). This study will contribute to a better understanding the kinematics of the reference frame and the elastic parameters on a regional scale.