Venus, often referred to as Earth’s evil twin, is renowned for its unique and complex geological features. Among these intriguing aspects are the planet's striking pancake domes—massive, circular volcanic formations that bear a resemblance to oversized flapjacks cooking on the planet's extreme surface. While scientists have traditionally believed that these domes were formed by the gradual ooze of thick, viscous lava, recent research suggests an additional critical factor influencing their creation.
A research team recently revisited the formation of these distinctive structures by studying one of the largest known domes on Venus, named Narina Tholus. This dome measures nearly 90 miles (145 kilometers) in diameter. Utilizing radar data collected by NASA’s Magellan mission in the 1990s, the scientists constructed a detailed digital model of Narina Tholus. This model aimed to assess how various lava properties and surface behaviors could impact the dome’s shape.
The simulations conducted by the team revealed a surprising finding: lava alone could not fully explain the dome’s flattened top and sharply sloping edges. Instead, the research indicated that crustal flexure—the ability of Venus’ lithosphere to bend under pressure—played a significant role in the dome's formation. The researchers noted that increased flexure leads to flatter dome tops and steeper sides, causing lava to accumulate and cease spreading upon encountering a soft, deformable crust. This interaction effectively shapes the dome into its characteristic pancake form.
But can the formation of these pancake domes be attributed solely to the type of lava involved? According to Madison Borrelli, a postdoctoral researcher at the Georgia Institute of Technology and lead author of the study, the answer is likely no. In an email to Live Science, Borrelli emphasized that the models were successful only when they utilized ultra-dense, highly viscous lava. This particular type of lava is more than a trillion times thicker than ketchup and twice as dense as water, resulting in an extremely slow flow that could take hundreds of thousands of Earth years to settle into its final shape.
This ultra-thick lava also accounted for the crustal bulges observed around various domes—a feature noted in previous studies but not fully understood until now. The behavior of this lava, when interacting with a pliable crust, leads to formations characterized by flat summits and steep flanks, emulating the pancake domes scattered across the surface of Venus.
While this study provides compelling evidence for the newly proposed formation mechanism, it is currently based on just one dome. Broader validation of these findings will depend on upcoming missions such as NASA’s VERITAS and DAVINCI. These missions are designed to deliver enhanced topographic data and geological insights from Venus' surface, aiming to explore thousands of other volcanic features across the planet.
If the interactions between crust and lava observed in Narina Tholus are confirmed to be consistent across Venus, it could significantly alter our understanding of the planet's geological evolution. This research may provide essential clues regarding why Venus has diverged so dramatically from Earth, despite their similarities in size and composition.
