IAG-IASPEI 2017

講演情報

Poster

IASPEI Symposia » S19. Planetary seismology

[S19-P] Poster

2017年8月1日(火) 15:30 〜 16:30 Event Hall (The KOBE Chamber of Commerce and Industry, 2F)

15:30 〜 16:30

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

Ebru Bozdag1, 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.