Statistical Approach Applied to the Investigation of Deformations Associated with the Effect of Hydrological Load in the Brazilian Amazon

Abstract

Points on the Earth's surface are subject to displacement caused by geodynamic and the crustal deformation phenomena, such as plate movement, volcanic activity, hydrological load, etc. In this sense, the investigations of the effect of the hydrological load have concentrated on the deformations associated with the vertical components. However, due to the viscoelasticity of the Earth, such deformations also affect the horizontal (planimetric) components. Therefore, the objective of this work is to investigate the deformations that occurred in two stations of the RBMC (NAUS and AMBC) that border the Rio Negro, in the Brazilian Amazon, based on statistical analyzes of trend and periodicity (seasonality and cycle) of time series positional and linimetric. It was observed that in both stations the Δn and Δe components showed a significant trend (continuous deformation), which did not occur for the Δu component. Continuous strain rates of 0.01198 and -0.00347 m/year and 0.01084 and -0.00476 m/year were observed for Δn and Δe from the NAUS and AMBC stations, respectively. The periodic deformations of NAUS Δn and Δu showed seasonal lag similar to that of linimetric quotas (365.2 days), which did not occur for Δe (1217.2 days). The extremes of such deformations occur before the flood peaks in 100% of the years for Δn and 90% for Δu and, after the drought valleys, in 80% of the years in Δn and Δu. Finally, the extremes of AMBC's periodic deformations of Δn and Δu occurred before peaks and valleys in 100% of years. The opposite was observed for Δe in 100% of the years.