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Structure Along the Martian Dichotomy Constrained by Rayleigh and Love Waves and their Overtones
  • +12
  • Doyeon Kim,
  • S. C. Stähler,
  • S. Ceylan,
  • V. Lekic,
  • R. Maguire,
  • G. Zenhäusern,
  • J. Clinton,
  • D. Giardini,
  • A. Khan,
  • M. P. Panning,
  • P. Davis,
  • M. Wieczorek,
  • N. Schmerr,
  • P. Lognonné,
  • W. B. Banerdt
Doyeon Kim

Corresponding Author:[email protected]

Author Profile
S. C. Stähler
Institute of Geophysics, ETH Zürich
S. Ceylan
Institute of Geophysics, ETH Zürich
V. Lekic
Department of Geology, University of Maryland
R. Maguire
Department of Geology, University of Illinois Urbana-Champaign
G. Zenhäusern
Institute of Geophysics, ETH Zürich
J. Clinton
Swiss Seismological Service, ETH Zürich
D. Giardini
Institute of Geophysics, ETH Zürich
A. Khan
Institute of Geophysics, ETH Zürich
M. P. Panning
Jet Propulsion Laboratory, California Institute of Technology
P. Davis
Department of Earth, Planetary and Space Sciences, University of California
M. Wieczorek
Laboratoire Lagrange, Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS
N. Schmerr
Department of Geology, University of Maryland
P. Lognonné
Institut de Physique du Globe de Paris, Université de Paris, CNRS
W. B. Banerdt
Jet Propulsion Laboratory, California Institute of Technology

Abstract

Using seismic recordings of event S1222a, we measure dispersion curves of Rayleigh and Love waves, including their first overtones, and invert these for shear velocity (Vs) and radial anisotropic structure of the martian crust. The crustal structure along the topographic dichotomy is characterized by a fairly uniform vertically-polarized shear velocity (Vsv) of 3.17 km/s between ~5-30 km depth, compatible with the previous study by Kim et al. (2022). Radial anisotropy as large as 12 % (Vsh > Vsv) is required in the crust between 5-40 km depth. At greater depths, we observe a large discontinuity near 63 ± 10 km, below which Vsv reaches 4.1 km/s. We interpret this velocity increase as the crust-mantle boundary along the path. Combined gravimetric modeling suggests that the observed average crustal thickness favors the absence of large-scale density differences across the topographic dichotomy.