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Surface Wave Constraints on Crustal Structure Beneath Elysium Planitia

Description: 

The properties of the Martian crust, including its thickness, composition, and porosity, provide invaluable constraints on the origin and geological evolution of Mars. Surface wave observations from marsquakes recorded by InSight’s seismometer SEIS (Seismic Experiment for Internal Structure) have provided the best direct constraints on Martian crustal structure to date. However, surface wave signals have only been unequivocally identified in three events, limiting our understanding of crustal heterogeneity. In this study, we identify fundamental mode Rayleigh wave signals in two Cerberus Fossae marsquakes (S0235b and S1133c) and invert group velocity dispersion measurements for shear wave speed structure along two corridors in Elysium Planitia. Surface wave signals are isolated using frequency-dependent polarization analysis, which allows us to filter seismic energy based on particle motion. Rayleigh wave signals from S0235b and S1133c exhibit retrograde elliptical motion and yield back azimuths broadly consistent with body wave polarization analysis. We find that the average shear wave speed structure along the S0235b path is 8% slower than along the S1133c path, although much of the discrepancy could be due to uncertainty in marsquake source locations. Our results provide new insights into lateral variations in the crustal velocity structure on Mars and offer clues about the source depths of Cerberus Fossae marsquakes.

Session: Earth’s Structure from the Crust to the Core - II

Type: Oral

Date: 4/16/2025

Presentation Time: 10:45 AM (local time)

Presenting Author: Ross

Student Presenter: No

Invited Presentation: Yes

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Authors