EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Joint inversion of receiver functions and apparent incidence angles to investigate the crustal structure of Mars

Rakshit Joshi1, Brigitte Knapmeyer-Endrun2, Klaus Mosegaard3, Felix Bissig4, Amir Khan4, Mark Panning5, Simon Staehler4, Benoit Tauzin6, Vedran Lekic7, John-Robert Scholz1, Paul Davis8, Rudolf Widmer-Schnidrig9, Raphael Garcia10, Baptiste Pinot10, Philippe Lognonné11, and Ulrich Christensen1
Rakshit Joshi et al.
  • 1Max-Planck Institute for Solar System Science, Planets and Comets, Göttingen, Germany
  • 2Bensberg Observatory, University of Cologne, Cologne, Germany
  • 3Neils Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 4Institute for Geophysics, ETH Zürich, Zürich, Switzerland
  • 5Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 6Laboratoire de Sciences de la Terre, Université de Lyon I, France
  • 7Department of Geology, University of Maryland, College Park, MD, USA
  • 8University of California, Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, USA
  • 9Black Forest Observatory, Institute of Geodesy, Stuttgart University, Germany
  • 10Institut Supérieur de l’Aéronautique et de l’Espace SUPAERO, Toulouse, France
  • 11Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris

Since InSight (the Interior Exploration using Geodesy and Heat Transport) landed 26 months ago and deployed an ultra sensitive broadband seismometer(SEIS) on the surface of Mars, around 500 seismic events of diverse variety have been detected, making it possible to directly analyze the subsurface properties of Mars for the very first time. One of the primary goals of the mission is to retrieve the crustal structure below the landing site. Current estimates differ by more than 100% for the average crustal thickness. Since data from orbital gravity measurementsprovide information on relative variations of crustal thickness but not absolute values, this landing site measurement could serve as a tie point to retrieve global crustal structure models. To do so, we propose using a joint inversion of receiver functions and apparent incidence angles, which contain information on absolute S-wave velocities of the subsurface. Since receiver function inversions suffer from a velocity depth trade-off, we in addition exploit a simple relation which defines apparent S-wave velocity as a function of observed apparent P-wave incidence angles to constrain the parameter space. Finally we use the Neighbourhood Algorithm for the inversion of a suitable joint objective function. The resulting ensemble of models is then used to derive the full uncertainty estimates for each model parameter. Before its application on data from InSight mission, we successfully tested the method on Mars synthetics and terrestrial data from various geological settings using both single and multiple events. Using the same method, we have previously been able to constrain the S-wave velocity and depth for the first inter-crustal layer of Mars between 1.7 to 2.1 km/s and 8 to 11 km, respectively. Here we present the results of applying this technique on our selected data set from the InSight mission. Results show that the data can be explained equally well by models with 2 or 3 crustal layers with constant velocities. Due to the limited data set it is difficult to resolve the ambiguity of this bi-modal solution. We therefore investigate information theoretic statistical tests as a model selection criteria and discuss their relevance and implications in seismological framework.

How to cite: Joshi, R., Knapmeyer-Endrun, B., Mosegaard, K., Bissig, F., Khan, A., Panning, M., Staehler, S., Tauzin, B., Lekic, V., Scholz, J.-R., Davis, P., Widmer-Schnidrig, R., Garcia, R., Pinot, B., Lognonné, P., and Christensen, U.: Joint inversion of receiver functions and apparent incidence angles to investigate the crustal structure of Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9470,, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.