<Press Release>Temporal variation and frequency dependence of seismic ambient noise on Mars from polarization analysis

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We applied a polarization analysis of InSight seismic data to estimate the temporal variation and frequency dependence of the Martian ambient noise field. Low-frequency (<1 Hz) P-waves show a diurnal variation in their dominant back-azimuths that are apparently related to wind and the direction of sunlight in a distant area. Low-frequency Rayleigh waves (0.25–1 Hz) show diurnal variations and a dominant back-azimuth related to the wind direction in a nearby area. Low-frequency signals that are derived mainly from wind may be sensitive to subsurface structure deeper than the lithological boundary derived from an autocorrelation analysis. On the other hand, dominant back-azimuths of high-frequency (>1 Hz) waves point toward the InSight lander, especially in daytime, indicating that wind-induced lander noise is dominant at high frequencies. These results point to the presence of several ambient noise sources as well as geologic structure at the landing site.