Final summary of team achievements
In the next decade, we will unravel some of Venus’ secrets through the multitude of Venus-bound missions, but determining its seismic activity is not one of their main goals. At the same time, more and more studies suggest that Venus could be seismically active today with active volcanism all but confirmed. Insights into Venus’ seismicity and detecting seismic waves can help us to understand the interior of the planet, which is quite unknown.
In an effort to push the frontiers of Venus seismology, our ISSI team estimated the current seismicity of Venus and the thickness of its seismogenic layer (the region where quakes can occur) and assessed different seismic wave detection methods.
If we assume that there is not much seismic activity on Venus (comparable to the interior of tectonic plates on Earth), we found that a few hundred venusquakes per year with magnitude 4 or higher could occur. For an upper limit on the seismicity on Venus, we assumed that Venus has regions with more seismic activity: the so-called coronae, fold belts, and rifts. Depending on our assumptions, we found that over 17,000 venusquakes with magnitude 4 or higher could occur in a year, which is similar to the amount of seismicity on Earth.
Using the 600°C isotherm as a proxy for the depth limit of the seismogenic layer of Venus, we used gravity and topography data and geodynamic models to estimate the thermal structure of Venus’ subsurface and, based on this, determine the thickness of the seismogenic layer. We found that the seismogenic thickness of Venus varies between about 2 and 35 km.
To detect seismic signals on Venus, we explored the detection capabilities of ground deformation sensors, infrared sensors on balloons in Venus’ atmosphere, and airglow imagers that could be mounted on orbiters around Venus. Considering the long mission duration and large field of view of orbiters, airglow imagers currently have the highest potential seismic wave detection capabilities.
Based on our results, we urge space agencies that the seismological exploration of Venus — “the quest for quakes on Venus” — should be their next priority.
Team mission statement & goals
With the selection of multiple missions to Venus by NASA and ESA planned to launch in the coming decade, we will greatly improve our understanding of Venus as a planet. However, the selected missions cannot tell us anything about the seismicity on Venus, which is a crucial observable to constrain the tectonic activity and geodynamic regime of the planet, and its interior structure. We have gathered an interdisciplinary team of experts in seismology, geology, and geodynamics to assess the seismic activity on Venus from a theoretical and instrumental perspective. We aim to provide estimates of the current seismicity on Venus based on constraints from e.g., geodynamic modelling and surface fault mapping. Using these estimates, we aim to determine the associated ground motion and atmospheric perturbations that can be expected on Venus as a result of seismicity.
To detect these seismic signals eventually during future missions, we will review the feasibility, advantages, and disadvantages of seismic observation techniques on the surface (e.g., broadband seismometers, distributed acoustic sensing methods), from a balloon, and from orbit.
Consolidating the results from both the theoretical and instrumental parts of this proposal will make a major contribution to understanding the present-day seismicity of Venus and result in recommendations for future payload configurations for Venus missions with seismological science objectives.
Hence, with this international team, we aim to advance the current state-of-the-art of Venus seismology and pave the way for future geophysical mission studies that will extend the Venus science programme beyond the current decade.
For more information, you can find the full proposal for our ISSI team here.
Banner image by Lucía Perez-Diaz: www.luciaperezdiaz.com