South Africa does not tremble, it rises. In this country deemed geologically calm, ultra-preccosed measuring instruments have highlighted a progressive uprising of the earth's crust. Millimeter per millimeter, some regions gain at altitude, without a crash or apparent cracks. This slow movement intrigues geophysicists, especially since it does not result from a tectonic thrust, but from a much more insidious factor. The uprising of South Africa reveals the physical traces of a phenomenon which, by dint of repeated droughts, slowly modifies the geography of the continent.
These data, collected between 2012 and 2020, show a slow but generalized uprising of the earthly crust. Researchers used high -precision time series to extract this trend, eliminating seasonal disturbances and occasional variations. The study, published in JGR Solid Earth, relies on a rigorous treatment of vertical signals to distinguish real movements from the soil from measuring artefacts. This device, initially designed for engineering and meteorology, is now a key tool for geophysical observation.
The uprising of South Africa results from a massive water loss
If the uprising of South Africa seems to come from depths, the real cause is on the surface. Christian Mielke's team has observed an elevation of the soil in the areas struck by drought. Indeed, the disappearance of groundwater modifies the pressure exerted on the crust. By crossing the data from the Grace satellite and the hydrological surveys, the researchers have established a direct link. The uprising of South Africa accelerates especially where the tablecloths are empty.
This phenomenon is explained by a simple physical principle. When a region loses a large amount of water stored in water tables or soils, it is lighter. The ground, hitherto compressed by the mass of water, is slowly relaxing, like a sponge which resumes its shape after being pressed. This mechanism, called elastic rebound, has already been observed in other regions struck by drought, notably in California.
Iflscience underlines that the most affected provinces – such as the Western Cape and Gauteng – recorded up to 6 millimeters of uprising during this period. These data not only reveal the severity of the water crisis, but also the tangible impact of these droughts on the country's topography.
A geography jostled by climate change
This progressive uprising is not an isolated case. It is part of a wider dynamic, linked to the climate. For twenty years, South Africa has been facing recurring droughts. That of 2018 at Cape Town remains the most striking. The city came close to the “Day Zero”, this moment when the water could have completely missed.
These shortages get worse with urbanization, intensive agriculture and an increasingly unstable climate. El Niño accentuates these dry cycles, often amplified by poor management or a lack of preparation. According to Professor Karegar's team, the loss of water since 2000 reaches 71 millimeters throughout the country. This drop was enough to cause an average uprising of six millimeters.
This slight lifting of the soil, almost imperceptible to the naked eye, then becomes an alarm signal. It translates a deep imbalance between human needs, resource management and natural charging capacities. Hydrological geodesy, still little known to the general public, is gradually imposed as a precious tool to follow the cumulative effects of climate change.
