Numerical Modeling of Global Seismic Wave Propagation in the Whole Mars Models and Effect of Lateral Crustal Variation

Investigating the interior structure of Mars is important to study not only its past and present state and future evolution, but also the formation and evolution of the Earth and solar system. Seismological methods played import roles in the study of the Earth and Moon’s interior. The first mission about Martian seismology began in 1976, but no seismic events were convincingly detected during the observation. The InSight Spacecraft landed on Mars on November 26, 2018 in Elysium Planitia and installed the first seismometer on Mars. It will provide the in situ observation of interior structure and seismic activity of Mars for the first time. In this study, we perform numerical modelling of seismic wave propagation in whole-mars models by solving the seismic wave equations using a hybrid pseudospectral and finite difference method on staggered grid. Firstly, based on the Martian internal models derived from geochemical analysis (Sohl and Spohn, 1997), we present numerical simulations of seismic wave propagation in the whole Mars models. The generation and propagation of various seismic phases in the whole Mars models are shown by synthetic seismograms and wavefield snapshots. We analyze the effects of crustal thickness and depth of core mantle boundary on seismic wave propagation. Then based on the present model of Martian crustal thickness (Wieczorek and Zuber, 2004), we simulate seismic wave propagation in laterally heterogeneous Martian crust and analyze the influence of lateral heterogeneity on global seismic wave propagation. Multiple reflections and conversions of seismic waves and their constructive interference occurred inside the low-velocity Martian crust form reverberating wave trains. Thickness of Martian crust has strong effect on the propagation of multiple surface reflections and surface waves. Seismic reflections from core-mantle boundary can be clearly identified from the calculated transverse component seismogram.