Is the Deep Martian Mantle Heterogeneous? A Reappraisal of Seismological Evidences

Abstract It has been proposed that the deep Martian mantle contains distributed heterogeneities preserved since the accretion of the planet. This result relies on a multiple‐scattering interpretation of frequency‐dependent arrival times of ‐waves detected in the spectrograms of teleseismic Martian events. In this work, I present a simple envelope‐based methodology to measure arrival times of ‐wave signals characteristic of Mars and systematically investigate high‐frequency data. Besides teleseismic events, I report the detection of frequency‐dependent ‐wave arrival times for three regional events, with a different behavior between the vertical and horizontal components. I critically examine the possibility to explain these observations with scattering theory and conclude that it is incompatible with the data. Instead, I propose that the observations result from a detection threshold effect for weak emergent signals. My analysis calls into question the scattering interpretation of frequency‐dependent arrival times and the presence of heterogeneities in the Martian mantle.