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Free keywords:
martian crust; marsquakes; Rayleigh waves ellipticity; receiver
functions
Abstract:
For the first time, we measured the ellipticity of direct Rayleigh waves at intermediate periods (15-35 s) on Mars using the recordings of three large seismic Martian events, including S1222a, the largest event recorded by the InSight mission. These measurements, together with P-to-s receiver functions and P-wave reflection times, were utilized for performing a joint inversion of the local crustal structure at the InSight landing site. Our inversion results are compatible with previously reported intra-crustal discontinuities around 10 and 20 km depths, whereas the preferred models show a strong discontinuity at ∼37 km, which is interpreted as the crust-mantle interface. Additionally, we support the presence of a shallow low-velocity layer of 2-3 km thickness. Compared to nearby regions, lower seismic wave velocities are derived for the crust, suggesting a higher porosity or alteration of the whole local crust.
