Subsurface Structure at the InSight Landing Site From Compliance Measurements by Seismic and Meteorological Experiments

B Kenda (1) , M Drilleau (2) , R Garcia (3) , T Kawamura (1) , N Murdoch (4) , N Compaire (4) , P Lognonné (1) , A Spiga (5) , R Widmer‐schnidrig (6) , P Delage (7) , V Ansan (2) , C Vrettos (8) , S Rodriguez (1) , W Banerdt (9) , D Banfield (10) , D Antonangeli (11, 12) , U Christensen (13) , D Mimoun (4) , A Mocquet (2) , T Spohn (14)

1 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
2 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
3 IPG Paris - Institut de Physique du Globe de Paris
4 ISAE-SUPAERO - Institut Supérieur de l'Aéronautique et de l'Espace
5 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
6 University of Stuttgart
7 ENPC - École des Ponts ParisTech
8 TU Kaiserslautern - Technical University of Kaiserslautern
9 JPL - Jet Propulsion Laboratory
10 Cornell University [New York]
11 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
12 MNHN - Muséum national d'Histoire naturelle
13 MPS - Max-Planck-Institut für Sonnensystemforschung
14 DLR - German Aerospace Center

Measurements of ground compliance at the InSight landing site-describing the surface response to pressure loading-are obtained from seismic and meteorological data. Compliance observations show an increase with frequency indicating the presence of a stiffer rock layer beneath the exposed regolith. We performed a Markov chain Monte Carlo inversion to investigate the vertical profile of the elastic parameters down to 20 m below InSight. Compliance was inverted both freely and assuming prior knowledge of compaction in the regolith, and the limitations and strengths of the methods were assessed on the basis of theoretical considerations and synthetic tests. The inverted Young modulus exhibits an increase by a factor of 10-100 over the first 10-15 m, compatible with a structural discontinuity between 0.7 and 7 m. The proposed scheme can be used for joint inversion of other seismic, geological, or mechanical constraints to refine the resulting vertical section.

Keywords: compliance; InSight; inversion; regolith; subsurface; Young modulus

Domains: Physics [physics]; Astrophysics [astro-ph]; Earth and Planetary Astrophysics [astro-ph.EP]

B Kenda, M Drilleau, R Garcia, T Kawamura, N Murdoch, et al.. Subsurface Structure at the InSight Landing Site From Compliance Measurements by Seismic and Meteorological Experiments. Journal of Geophysical Research. Planets, 2020, 125 (6), pp.e2020JE006387. ⟨10.1029/2020je006387⟩. ⟨hal-03657932⟩