EGU24-19431, updated on 11 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Multi-scale investigation of the InSight landing site, on Mars, using one-station seismology

Sebastian Carrasco1, Brigitte Knapmeyer-Endrun2, Ludovic Margerin3, Eleonore Stutzmann4, Martin Schimmel5, Keisuke Onodera4,6, Sabrina Menina4, Wanbo Xiao4,7, Zongbo Xu4, Cedric Schmelzbach8, Manuel Hobiger9, and Philippe Lognonné4
Sebastian Carrasco et al.
  • 1University of Cologne, Bensberg Earthquake Observatory, Bergisch Gladbach, Germany (
  • 2Microgravity User Support Center, German Aerospace Center (DLR), Cologne, Germany
  • 3IRAP, Université Toulouse III Paul Sabatier, CNRS, CNES, Toulouse, France
  • 4Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France
  • 5Geosciences Barcelona, CSIC, Barcelona, Spain
  • 6Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
  • 7Department of Geophysics, School of Earth and Space Sciences, Peking University, Beijng, China
  • 8Institute of Geophysics, ETH Zurich, Sonneggstr. 5, 8092 Zurich, Switzerland
  • 9Federal Institute for Geosciences and Natural Resources (BGR), 30655 Hannover, Germany

The internal structure of a planet provides constraints for understanding its evolution and dynamics. In November 2018, the InSight spacecraft landed on Mars and deployed a set of geophysical instruments, including one seismological station. In this work, the subsurface structure at the InSight landing site (ILS) is explored, from the shallow subsurface to crustal depths, by applying single-station seismological techniques (SST) on martian ambient vibrations and seismic events data.

The shallow subsurface at the ILS, in the order of meters, is investigated using the horizontal-to-vertical spectral ratios (HVSR) from the coda of martian seismic events. Assuming a fully diffuse wavefield, a nonlinear inversion using the conditional Neighbourhood Algorithm (NA) allowed to map the shallow subsurface at the ILS. Due to the non-uniqueness problem, different sets of models are retrieved. The 8 Hz HVSR peak can be explained by a Rayleigh wave resonance due to a shallow high-velocity layer, while the 2.4 Hz trough is explained by a P-wave resonance due to a buried low-velocity layer. The kilometer-scale subsurface was constrained by Rayleigh wave ellipticity measurements from large martian seismic events. The ellipticity measurements (0.03-0.07 Hz) were jointly inverted with P-to-s Receiver Functions and P-wave lag times from autocorrelations, to provide a subsurface model for the martian crust at the ILS. The joint inversion allowed the thickness and velocities of a new surface layer, previously proposed only conceptually, to be constrained by multiple seismological data. The HVSR in the 0.06-0.5 Hz frequency range from the coda of S1222a, the largest event ever recorded on Mars, suggests a gradual transition from shallow to crustal depths and consolidates the group of shallow subsurface models with the largest shear-wave velocities as the most compatible with the crustal structure.

A comprehensive multi-scale model of the ILS subsurface is proposed. The ILS is characterized by the emplacement of a low-velocity regolith/coarse ejecta layer over a high-velocity Amazonian fractured lava flow (~2 km/s, ~30 m thick). A buried Late Hesperian-Amazonian sedimentary layer is deposited below (~450 m/s, ~30 m thick), underlain by a heavily weathered Early Hesperian lava flow. The latter overlays a thick, likely Noachian sedimentary layer that extends to a depth of 2-3 km. This shallow structure forms the first crustal layer derived from the joint inversion. Deeper crustal layers are consistent with other reported ILS models, with intracrustal discontinuities at 8-12 km and 18-23 km depth. The Moho depth at the ILS is found at 35-45 km depth. Shear-wave velocities above ~20 km depth are lower than 2.5 km/s, slower than in other regions of Mars, suggesting a higher alteration due to local processes or a different origin of the upper crust at the ILS. The proposed model is consistent with the geologic history of Mars and other independent observations, confirming the great potential of SST for multi-scale investigation of, e.g., other planetary bodies or understudied regions on Earth.

How to cite: Carrasco, S., Knapmeyer-Endrun, B., Margerin, L., Stutzmann, E., Schimmel, M., Onodera, K., Menina, S., Xiao, W., Xu, Z., Schmelzbach, C., Hobiger, M., and Lognonné, P.: Multi-scale investigation of the InSight landing site, on Mars, using one-station seismology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19431,, 2024.