Simulations of Seismic Wave Propagation on Mars

Ebru Bozdağ (1, 2) , Youyi Ruan (1) , Nathan Metthez (3) , Amir R. Khan (4) , Kuangdai Leng (5) , Martin van Driel , Mark Wieczorek (6) , Attilio Rivoldini (7) , Carene Larmat (8) , Domenico Giardini (9) , Jeroen Tromp (1) , Philippe Lognonné (10) , Bruce Banerdt (11)

1 Department of Geosciences [Princeton]
2 GEOAZUR 7329 - Géoazur
3 D-BSSE - Department of Biosystems Science and Engineering [ETH Zürich]
4 Institute of Geophysics [ETH Zürich]
5 University of Oxford
6 LAGRANGE - Joseph Louis LAGRANGE
7 ROB - Royal Observatory of Belgium = Observatoire Royal de Belgique
8 IPGP - Institut de Physique du Globe de Paris
9 CSE Lab - Computational Science and Engineering Laboratory
10 DGSP (UMR_7096) - Département de géophysique spatiale et planétaire
11 JPL - Jet Propulsion Laboratory

We present global and regional synthetic seismograms computed for 1D and 3D Mars models based on the spectral-element method. For global simulations, we implemented a radially-symmetric Mars model with a 110 km thick crust (Sohl and Spohn in J. Geophys. Res., Planets 102(E1):1613–1635, 1997). For this 1D model, we successfully benchmarked the 3D seismic wave propagation solver SPECFEM3D_GLOBE (Komatitsch and Tromp in Geophys. J. Int. 149(2):390–412, 2002a; 150(1):303–318, 2002b) against the 2D axisymmetric wave propagation solver AxiSEM (Nissen-Meyer et al. in Solid Earth 5(1):425–445, 2014) at periods down to 10 s. We also present higher-resolution body-wave simulations with AxiSEM down to 1 s in a model with a more complex 1D crust, revealing wave propagation effects that would have been difficult to interpret based on ray theory. For 3D global simulations based on SPECFEM3D_GLOBE, we superimposed 3D crustal thickness variations capturing the distinct crustal dichotomy between Mars’ northern and southern hemispheres, as well as topography, ellipticity, gravity, and rotation. The global simulations clearly indicate that the 3D crust speeds up body waves compared to the reference 1D model, whereas it significantly changes surface waveforms and their dispersive character depending on its thickness. We also perform regional simulations with the solver SES3D (Fichtner et al. Geophys. J. Int. 179:1703–1725, 2009) based on 3D crustal models derived from surface composition, thereby addressing the effects of various distinct crustal features down to 2 s. The regional simulations confirm the strong effects of crustal variations on waveforms. We conclude that the numerical tools are ready for examining more scenarios, including various other seismic models and sources.

Domaines: Sciences de la Terre; Planétologie

Ebru Bozdağ, Youyi Ruan, Nathan Metthez, Amir R. Khan, Kuangdai Leng, et al.. Simulations of Seismic Wave Propagation on Mars. Space Science Reviews, 2017, 211 (1-4), pp.571 - 594. ⟨10.1007/s11214-017-0350-z⟩. ⟨hal-01734543⟩