Venus is one of the most hostile worlds in the solar system. Surface temperatures reach hundreds of degrees Celsius, and there is no comparable ocean on Earth. For many years, scientists thought Venus was geologically inactive. However, more recent discoveries suggest that the planet is still geologically “alive” and may even contain active volcanoes.
One of the strongest signs of tectonic activity is Venus’s giant rift valley. Similar geological formations exist on Earth, such as in the African Rift Valley, but Venus’ version can span 10,000 kilometers.
Are Venus’ rift valleys still active?
Scientists are not sure when these giant cracks formed. Many geoscientists hypothesize that they developed more than 100 million years ago and are simply ancient features preserved on the Earth’s surface.
A new study by ETH casts doubt on that view. Researchers led by Taras Gelya, professor of geodynamics in the Department of Earth and Planetary Sciences, used advanced computer models to show that parts of Venus’ rift valleys may be much younger than previously thought. Their study also provides new evidence for the long-standing debate over whether Venus remains geologically active.
This study natural earth science. Lead author Xi Yang completed this study during his master’s degree under Gerya’s supervision.
New 3D simulation reveals young cracks
Yang and his colleagues have created the first high-resolution 3D computer simulation of Venus’s cracks. These models allowed the team to reproduce the structure in greater detail and develop a more accurate explanation of how it formed.
Previous simulations were primarily two-dimensional and relied on simplifying assumptions about the behavior of planetary material. A new approach has given researchers a more realistic view of how Venus’ crust stretches, moves and relaxes over time.
The results show that when the rift is geologically young, wide uplifted ridges, called rift flanks, develop along the flanks of the rift. These raised features appear while the crack is still moving or shortly after it has stopped moving.
Simulations also show that Venus’ cracks could widen faster than scientists once estimated. According to the model, it can increase in width by about 3-10 centimeters every year.
The sides of the crack fade as the crust relaxes
The researchers found that the sides of the rift valley begin to flatten relatively quickly after the tectonic movement ends. As a rift system ages, its ridges become lower, wider, and less defined.
This process is different from what happens on Earth. Here, erosion gradually wears away mountains and other landforms. On Venus, the sides of the cracks sink as the crust slowly loosens after being stretched.
The wide, uplifted flanks of the rift valley predicted by the new simulations also appear in images captured by the Magellan spacecraft during a mission in the 1990s. The similarities between the modeled structures and the observed landscape support the theory that some of these fractures formed relatively recently.
By combining their simulation results with spacecraft observations, the researchers concluded that Venus’ interior is more active and dynamic than previously assumed.
“This result will help us more precisely assess Venus’s tectonic activity,” Gelija said.
Guide future Venus missions
The model could help scientists identify areas where geological activity may still be occurring. These areas could be priority targets for future missions looking for signs of active tectonic or volcanic activity.
The discovery could also advance scientists’ understanding of how rocky planets develop and evolve. The researchers hope this study will eventually provide clues that will make it easier to detect and study rocky exoplanets outside our solar system.
New mission to explore Venus
Scientific interest in Venus is growing as NASA and ESA prepare several missions to explore Earth’s neighboring planet.
ETH geophysics professors Paul Tackley and Taras Gerya are contributing to ESA’s EnVision mission along with their collaborators. Their team is developing instruments that the Venus probe will use to examine the planet’s surface.
EnVision is scheduled to launch in the early 2030s. This mission will study Venus in more detail, examining everything from the planet’s core to its upper atmosphere.
