Patagonia 2020

Our Earth reacts in different ways to changes in ice mass. Current ice mass changes cause an immediate elastic reaction, while ice-mass changes further back in the past still cause a response known as 'glacial isostatic adjustment' (GIA), as mantle materials pushed away by the previously existing ice masses flow back very slowly. This reaction is dependent on both the temporal change of the ice masses and the internal structure of the Earth. If the two reactions are to be separated, realistic GIA models are needed, based on measurements of the effects. The region of the southern Patagonian Ice Field is a complex area. It involves large ice masses in conjunction with considerable ice mass changes and a inhomogeneous structure of the Earth's mantle due to nearby plate boundaries. Using GNSS measurements, large height changes were measured in the region. However, elevation changes only provide insight into the described effects from one side.

The aim of this campaign is to determine gravity changes that result from a redistribution of the mantle materials and are therefore important observations for the creation of GIA models. This year, gravity values will be determined at several points and subsequent measurements in other years will then finally yield the desired gravity changes. The gravity values are determined using a so-called absolute gravimeter, which was provided by the BKG and will be operated by colleagues from the BKG and the AGGO during the campaign. In addition, heights are measured using GNSS in order to determine not only the changes in gravity but also the relationship to changes in height. However, since the absolute gravimeter does not measure exactly at the GNSS points attached to the ground, the height of the GNSS markings is transferred to the gravity point by means of leveling. As the gravity naturally also changes with altitude, we will use a relative gravimeter to determine the change in gravity as a function of altitude at the measurement points.