Detection of Crustal Uplift Deformation in Response to Glacier Wastage in Southern Patagonia

Abstract

The Southern Patagonian Icefield (SPI) is the largest continuous ice mass in the Southern Hemisphere outside Antarctica. It has been shrinking since the Little Ice Age (LIA) period, with increasing rates in recent years. An uplift of crustal deformation in response to this deglaciation process has been expected. The goal of this investigation is to analyze the crustal deformation caused by ice retreat using time-series data from continuous GPS stations (2015–2020) in the northern area of the SPI. For this purpose, we installed two continuous GPS stations on rocky nunataks of the SPI (the GRCS near Greve glacier and the GBCS close by Cerro Gorra Blanca). In addition, ice elevation changes (2000–2019) were analyzed by the co-registration of the SRTM digital elevation model and ICESat elevation data points. The results of the vertical components are positive (36.55 ± 2.58 mm a−1), with a maximum at GBCS, indicating the highest rate of crustal uplift ever continuously recorded in Patagonia; in addition, the mean horizontal velocities reached 11.7 mm a−1 with an azimuth of 43°. The negative ice elevation changes detected in the region have also accelerated in the recent two decades, with a median Δh (elevation change) of −3.36 ± 0.01 m a−1 in the ablation zone. The seasonality of the GPS signals was contrasted with the water levels of the main Patagonian lakes around the SPI, detecting a complex interplay between them. Hence, the study sheds light on the knowledge of the crustal uplift as evidence of the wastage experienced by the SPI glaciers.