No abstract

For the first time, we measured the ellipticity of direct Rayleigh waves at long 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 crust 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 resulting models show a strong discontinuity at ~37 km, which is interpreted as the crust-mantle interface. We propose the presence of a top shallow low-velocity layer of 2-3 km thickness. Compared to nearby regions, lower seismic wave velocities are derived for the local crust, thus suggesting a higher porosity or alteration of the whole local crust.

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A non-uniform distribution of scattering strength can have a profound impact on the spatio-temporal sensitivity of coda waves • We illustrate this using Monte Carlo simulations for models with either a volcanic, fault zone, or two half-spaces setting • The mean intensity, specific intensity, and energy flux, is key to understanding the decorrelation, travel-time, and scattering kernels, respectively

On 4 May 2022, the seismometer on Mars observed the largest marsquake (S1222a) during its operation. One of the most specific features of S1222a is the long event duration lasting more than 8 hr, in addition to the clear appearance of body and surface waves. As demonstrated on Earth, by modeling a long‐lasting and scattered surface wave with the radiative transfer theory under the isotropic scattering condition, we estimated the scattering and intrinsic quality factors of Mars (Qs and Qi). This study especially focused on the frequency range between 0.05–0.09 Hz, where Qs and Qi have not been constrained yet. Our results revealed that Qi = 1,000–1,500 and Qs = 30–500. By summarizing the Martian Qi and Qs estimated so far and by comparing them with those of other celestial bodies, we found that, overall, the Martian scattering and absorption properties showed Earth‐like values.