Estimating the seismicity of Venus by scaling Earth’s seismicity

Abstract

<p>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.<span> </span></p><p>Here, we provide new, preliminary estimates of Venus’ global annual seismic budget and the expected frequency of venusquakes per year. We obtain this estimate by scaling the seismicity of the Earth recorded in the CMT catalogue. We test different potential scaling factors based on e.g., the difference in mass, radius, potential seismogenic volume, etc. We also sort the earthquakes into their respective tectonic settings, which allows us to exclude irrelevant tectonic settings present on Earth, but most likely not on Venus from our analysis. This enables us to present a range of potential seismic budgets and venusquake frequencies per tectonic setting on Venus. <span> </span></p><p>This then provides a new estimate of the potential amount of seismicity on Venus. However, it is uncertain how valid this simple scaling approach is from Earth to Venus. Indeed, previous attempts of scaling the volcanism of Earth to Venus (Byrne & Krishnamoorthy, 2022; Van Zelst, 2022) resulted in numbers that aligned with independent estimates, but are still unconstrained and hard to verify until the announced missions fly. Therefore, in order to provide a more robust and holistic view of Venus’ anticipated seismicity, estimates using various different, independent methods should ideally be considered.</p><p>To provide exactly that, we set up the ISSI team ‘Seismicity on Venus: Prediction & Detection’. This is an interdisciplinary team of experts in seismology, geology, and geodynamics. Together we aim to assess the seismic activity on Venus from a theoretical and instrumental perspective. In addition to presenting our preliminary seismicity estimates from scaling Earth to Venus, we therefore also use this contribution to briefly introduce the team and its goals and present the preliminary findings from our first, week-long, dedicated in-person meeting aimed at further characterising Venus’ seismicity.<span> </span></p><p><strong>References</strong></p><p>Byrne, Paul K., and Siddharth Krishnamoorthy. "Estimates on the frequency of volcanic eruptions on Venus." Journal of Geophysical Research: Planets 127.1 (2022): e2021JE007040.</p><p>van Zelst, Iris. "Comment on “Estimates on the Frequency of Volcanic Eruptions on Venus” by Byrne & Krishnamoorthy (2022)." Journal of Geophysical Research: Planets (2022): e2022JE007448.</p>

Estimates on the Possible Annual Seismicity of Venus

“…For Venus, we calculate a likely minimum and maximum seismogenic thickness (see Van Zelst et al., 2024, for the data and scripts used in this study) from proposed end‐member thermal gradients of Venus' lithosphere (Bjonnes et al., 2021; Smrekar et al., 2023). Like for our Earth estimate, we calculate the depth corresponding to the 600°C isotherm, as this seems to limit the seismogenic zone on Earth most robustly.…”

“…The Jupyter Notebooks used to make the results and plot the figures as well as the CMT database and geospatial vector data (shapefiles) of the tectonic setting areas on Earth and Venus can be found in Van Zelst et al (2024). Explanations of individual files in this repository and additional figures and tables are provided in Supporting Information S1.…”

“…Hence, brittle deformation could also occur up to deeper isotherms in Venus' interior. Therefore, we also provide seismogenic thickness estimates assuming a temperature of 800°C as the limiting factor in Van Zelst et al (2024). However, here, we compute end-members of the possible annual seismicity on Venus using the 600°C isotherm, as this provides a better comparison with Earth studies that use the same isotherm value to define the base of the seismogenic layer.…”