Vertical Displacement Caused By Hydrological Influence In The Amazon Basin

Hydrologic loading studies are related to variables such as soil moisture, precipitation, and groundwater. These parameters are associated with water mass movements, which may affect the positioning of the Global Navigation Satellite System (GNSS) stations and the gravitational field in a seasonal mode. This study addresses the relationship between displacement and deformation variations observed in the Amazon Basin and local geological and climatic features. It also aims to understand mechanisms that may influence the water distribution and mass movement during the hydrological cycle. We have correlated the vertical displacement with soil moisture at different depths in the Amazon Basin. Our approach takes into consideration topography, soil type, water storage, hydrologic deformation model used, sediment thickness, and geology. We show that amplitude variation of soil moisture and water storage parameters depends on the region's geological nature, that is, whether it is dominated by sedimentary or igneous/metamorphic rocks. In areas dominated by sedimentary rocks, soil moisture increases with depth, while in regions dominated by igneous and metamorphic rocks, soil moisture decreases with depth. We conclude that geology and topography influence the vertical displacement associated with the hydrologic loading. We further show an East-West gradient in the Amazon Basin, in which the largest amplitudes of vertical displacement occur in the sedimentary basins to the East. A few stations in the sedimentary basins have less vertical displacement than expected. We argue that these areas may be associated with thinner and more compact sedimentary rock, or even with intrusive igneous rocks.