Although Venus possesses a similar amount of internal energy to Earth, it lacks plate tectonics. The study, published in Earth and Planetary Science Letters, reveals that the lithosphere – the outermost rigid layer – exhibits significant thickness differences between the north and south, affecting the number of volcanoes and, consequently, the planet's internal heat loss.
The northern hemisphere of Venus has a thinner lithosphere and twice as many volcanoes as the south. "It is logical that a thinner lithosphere facilitates the escape of the planet's internal heat through a greater number of volcanoes," explains Ignacio Romeo Briones, a researcher at UCM. This characteristic, previously unnoticed, is crucial for understanding how Venus loses internal heat without a lithospheric recycling mechanism like Earth's plate tectonics.
Previously, the existence of a special zone on Venus's surface known as the BAT anomaly (Beta, Atla, and Themis regions), characterized by a high concentration of volcanoes, was known. The novelty of this study is that the rest of the planet, outside BAT, shows statistically different behavior between the north and south, according to Marina Mendiburu-Eliçabe, a researcher at UCM.
From a scientific standpoint, this finding represents a significant advance in understanding Venus, the terrestrial planet most similar in size to Earth, yet with a completely different geological evolution. For the study, gravity and topography data from NASA's Magellan probe, launched in 1989, were analyzed.
Geophysical data were spatially categorized and cross-referenced with lithospheric geophysical models, revealing the north-south difference. "Currently, there is no single explanation for the origin of the lithospheric thickness difference between the north and south," concludes Javier Ruiz, a researcher at UCM, who notes they are already working on various hypotheses.
The study also involves the University of Cádiz, Washington University in St. Louis, and the Technical University of Denmark.
