Publication Date:
2023-11-27
Description:
〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉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.〈/p〉
Description:
Plain Language Summary:: As never before on Mars, we measured the characteristics of seismic waves traveling along the Martian surface that carry information about the crustal structure at the InSight site. We combined these measurements with two other local‐scale independent observations to derive a consolidated model for the crust underneath the InSight lander. Our results suggest a Martian crust with 4 layers and, particularly, one thin layer of about 2 km thickness close to the surface. The crust‐mantle discontinuity was found at ∼37 km depth, where the sharpest change in seismic wave velocity is observed. Overall, the seismic wave velocities of the local Martian crust at the InSight site are lower than those derived in other regions on Mars, which suggests a higher porosity or local alteration.〈/p〉
Description:
Key Points:
〈list list-type="bullet"〉
〈list-item〉
〈p xml:lang="en"〉Rayleigh waves ellipticity was measured between periods 15–35 s at the InSight landing site using large seismic events, including S1222a〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉A 4‐layer crust, including a shallow low‐velocity layer, is required to explain the ellipticity, receiver functions and P‐wave lag times〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Low crustal velocities are derived for the InSight site, which may be due to high porosity or heavy alteration at local scale〈/p〉〈/list-item〉
〈/list〉
〈/p〉
Description:
National Aeronautics and Space Administration
Description:
Agence Nationale de la Recherche
http://dx.doi.org/10.13039/501100001665
Description:
https://doi.org/10.12686/a19
Description:
https://doi.org/10.18715/SEIS.INSIGHT.XB_2016
Description:
https://doi.org/10.7914/SN/BQ
Description:
https://www.globalcmt.org/CMTsearch.html
Description:
https://github.com/scarrascom/Rellipy
Description:
https://doi.org/10.5281/zenodo.8051337
Description:
http://www.geopsy.org/
Keywords:
ddc:523
;
martian crust
;
marsquakes
;
Rayleigh waves ellipticity
;
receiver functions
Language:
English
Type:
doc-type:article
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