A numerical model of the SEIS leveling system transfer matrix and resonances: application to SEIS rotational seismology and dynamic ground interaction.

Abstract

International audienceThe 6 seismic sensors of the SEIS (Seismic Experiment for Interior Structure) instrument of the NASA InSight mission, the 3 VBBs (Very Broad Band) and 3 SPs (Short Period), are placed on a leveling system. This system provides the mechanical coupling of the instrument to the ground and ensure a level placement of the sensors on the Martian ground under yet unknown local conditions. We developed a simplified analytical model of this structure in order to reproduce its mechanical behavior by predicting its resonances and transfer function. This allows to estimate its effect on the data recorded on Mars by the VBBs and SPs. Moreover, the model can also help to constrain the subsurface properties and proves the possibility to make rotational seismology by estimating the performances of the 6 axes seismometer which are good enough for determining the wavefield gradient of the high-amplitude surface waves generated by the HP3 mole penetration. This will allow the measurement of the phase velocity of the associated Rayleigh waves