[S19-P] Poster

[S19-P-01] Seismic Wave Simulations on Mars : Comparisons between 1D interior models and effect of 3D structures

^○Ebru Bozdag^{1, 2}, Melanie Drilleau³, Philippe Lognonne³, Domenico Giardini⁴, Mark Panning⁵, John Clinton⁴, Antoine Mocquet⁶, Raphael Garcia⁷, Rene Weber⁸, Jeroen Tromp⁹, Mark Wieczorek¹⁰, Bruce Banerdt¹¹, Youyi Ruan⁹, Nathan Metthez⁴, Amir Khan⁴, Kuangdai Leng¹², Martin van Driel⁴, Carene Larmat¹³, Savas Caylan⁴, Eric Beucler⁶, SEIS Science Team¹⁴ (1.University of Nice Sophia Antipolis, Valbonne, France, 2.Colorado School of Mines, Golden, CO, USA, 3.IPGP, Paris, France, 4.ETHZ, Zurich, Switzerland, 5.University of Florida, Florida, FL, USA, 6.Unversity of Nantes, Nantes, France, 7.ISAE-Supaero, Toulouse, France, 8.NASA-MSFC, USA, 9.Princeton University, Princeton, NJ, USA, 10.Observatoire de la Cote d'Azur, Nice, France, 11. JPL-Caltech, USA, 12. Oxford University, Oxford, UK, 13. Los Alamos National Lab., NM, USA, 14. http://seis-insight.eu/)

As part of the Mars InSight mission, we explore the effects of 1D & 3D structural variations on seismic waveforms using various seismic wave propagation codes. Our motivation is to characterize seismic signals which we expect to receive from a single broad-band instrument onboard InSight.

Waveform modelling has been done by the team using different modelling techniques: modes summation, direct solution, AxiSEM, SPECFEM3D_GLOBE & SES3D. Modes, direct solution and AxiSEM seismograms have been benchmarked down to 2 s for spherically symmetric models whereas SPECFEM3D_GLOBE with AxiSEM down to 10 s. In all experiments numerical differences are much smaller than the lowest seismic noise expected for the mission. Similar benchmarks were also performed for travel times, group-velocity dispersion and body-wave amplitude estimations.

We also performed 3D global and regional simulations with SPECFEM3D GLOBE and SES3D. For 3D global simulations we superimposed 3D crustal thickness variations on top of 1D model of Sohl & Spohn (1997) capturing the distinct crustal dichotomy between Mars' northern and southern hemispheres, as well as topography, ellipticity, gravity, and rotation. The global simulations indicate clear enhancement in seismic wave amplitudes travelling through the region of Tharsis Montes where the thickest crust is located. 3D regional simulations based on 3D crustal models derived from surface composition, address the effects of various distinct crustal features down to 2 s confirming the strong effects of crustal variations on waveforms.

In order to compare the effect of the 1D structure on synthetics, we also compare teleseismic waveforms computed for 14 different 1D models down to 5 s using normal modes summation which enable us to compare and discuss the effects on waveforms of different crustal & mantle structure, and mantle attenuation. Similar comparisons are then made on the travel time & group velocities and body waves amplitudes.