A Global Survey of Gravitationally Deformed Volcanoes on Venus

Gravitational instabilities can develop at volcanoes of any size and in any geological setting and can lead to various types of volcano deformation, ranging from small-scale landslides on the flanks of the edifice to large, deep-seated sector collapses. As volcanoes grow, they impose an increasing load on the underlying basement, which can result in styles of gravitational deformation where the edifice sags or spreads outward under its own weight. In this study, we utilize our previously developed global catalog of volcanoes on Venus to analyze a subset of edifices that appears to have undergone gravitational deformation. We identify 162 volcanoes that display morphological evidence for gravitational deformation and classify them into four main categories based on associated deformational structures: landsliding, sector collapse, spreading, and sagging. Landsliding of volcano flanks or full sector collapse are the most common and geographically widespread deformational styles on Venus, and account for similar to 64% of our data set. Edifices exhibiting structures linked to volcano spreading and sagging are relatively rare; nonetheless, we note for the first time on Venus the presence on a shield volcano of flank terraces, structures linked to sagging. We find that deformed volcanoes are distributed globally, are found at a range of elevations, are spatially proximal to a variety of tectonic structures, and are associated with various crustal thickness values, which together suggest that there are numerous drivers of volcano deformation on Venus. The effect of gravity works to destabilize volcanoes of all shapes and sizes and in all geological settings on Earth. In fact, gravity can lead to failure of small or even large parts of a volcano. As volcanoes grow and become heavier, they either weigh down the ground below them or, if the ground is very rigid, flatten outwards. Here, we used a catalog of volcanoes on Venus that we previously published to identify and describe all the examples of gravity-deformed volcanoes on the planet. We found more than 160 such volcanoes and divided them into four major classes based on different types of collapse features. Deformed volcanoes are located across the entire surface of Venus, with a slightly higher concentration found in the Beta-Atla-Themis region. Furthermore, these collapsed edifices are situated in areas with different tectonic structures and are located at varying elevations across the planet, suggesting that there are multiple reasons why a volcano on Venus might collapse. We identify 162 volcanoes displaying structures associated with gravitational deformation on Venus Deformed volcanoes are geographically widespread but are somewhat concentrated in the Beta-Atla-Themis region We note examples of flank terraces on Tepev Montes, a structural indicator of volcano sagging that has not yet been documented on Venus