# Detection of Crustal Uplift Deformation in Response to Glacier Wastage in Southern Patagonia
## 5 Discussion
[19] matches with the results found in our study. In consequence, the collected GPS data over the SPI accumulation zone, the first of its type, represent a novel approach to improving future viscoelastic glacial isostatic adjustment models in the region. Our GPS stations are placed in a particular geological zone, affected by the subduction of the spreading-ridge system composed of the Nazca and Antarctic plates, from the Miocene to the present, which led to the formation of an asthenospheric window (Figure 1) [60; 61], contemporary with the onset of the Patagonian glaciations [62]. This gap in the asthenosphere generated thermal and chemical anomalies and consequent changes in the lithosphere-asthenosphere boundary below Patagonia [63], as well as a thinning of the lithosphere [19; 64]. Above this slab window, the viscoelastic response of the solid Earth to ice mass changes is fast [19]. This could be one of the causes of fast crustal uplift, as shown by our results. Hence, this slab window provides key evidence supporting the previously hypothesized connection between post-Little Ice Age anthropogenic ice mass loss and rapid geodetically observed glacial isostatic uplift [65]. The region is in a particular tectonic context since there is a point where three tectonic plates (South American, Nazca, and Antarctic) coexist at the north of the SPI (The triple junction point at Peninsula Taitao, see Figure 1). This interaction generated a window in the lithosphere through which the asthenosphere could flow and combine with surface layers, having geomechanical and geodynamic consequences such as regional deformation and a higher uplift rate than in other regions, e.g., Antarctica or Greenland [66; 25; 61; 67]. The horizontal displacements obtained in our study show a trend in a northeesterly direction with a rate of 14 mm a\({}^{-1}\). This indicates a regional-scale deformation, indicating that the SPI area can be considered as a non-South American craton sector that is the stable rigid part of the South American plate [26]. [PERSON] et al. [69] obtained a weak correlation for some stations in the Patagonian lakes with GRACE (2002-2017 period). The hydrological system surrounding the GPS stations is comprised of glacial lakes of the region, some of them the largest in Patagonia. However, the area is indeed under the influence of a complex hydrological system that refers to various sources of water, including glaciers, snow, canopy water, surface water (lakes, rivers, and reservoirs), soil moisture, and groundwater. In addition, the natural processes that we are investigating are dominated by an annual period, even the GPS signal. Distinguishing those signals in geodetic measurements is critical for monitoring spatiotemporal variations in continental water storage and tectonic signals [70]. GPS records are related to the integration of all tectonic and non-tectonic sources, including the mass loading from the atmosphere, ocean, snow, soil moisture, and groundwater [71]. Therefore, isolating the seasonal signals that demonstrate the interactions between solid Earth and the hydrological cycle remains a difficult task, especially in Patagonia [72]. Missing data and gross errors always exist in GPS time series due to inevitable factors of the environment and human activities, such as the replacement of the receiver antenna, bad observation conditions, signal interruptions between the satellite and receiver, among others [47]. These interruptions increase signal instability; moreover, GPS velocity solutions tend to be unstable until a 2-year data span is exceeded [73]. In spite of the interruptions, our two continuous GPS stations continuously recorded crustal deformations for more than two years providing novel insights into the complex natural factors' interplay taking place in the region. The possible signal instabilities and errors due to the harsh environment conditions affecting GPS receivers and antennas were overcome by the signal combination and data gap filling applied method.