How do rifts form in regions such as Beta Regio on Venus?

Rifts on Venus, such as those found in Beta Regio, form through tectonic processes driven by the planet's internal mantle dynamics. Unlike Earth, where plate tectonics involve horizontal movement, Venusian deformation is characterized by vertical motions.1

In regions like Beta Regio, large areas of the lithosphere are forced upward by mantle upwelling—a process where heat from the interior is transported toward the surface via convective motions. This upward pressure causes the surface to split, creating extensive rift valleys. These features are composed of numerous faults, with floors that typically sit 1–2 km (0.6–1.2 miles) below the surrounding terrain.21

These rifts often radiate outward from the centers of these raised regions, similar to the spokes of a wheel, and are frequently associated with volcanic eruptions. Because Venus lacks water, these rifts remain largely unaffected by the erosion processes that shape similar features on Earth or Mars.2