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Seismic Evidence of Active Deep Crustal Deformation Beneath Valles Marineris, Mars

Description: 

Valles Marineris, the largest canyon system in the Solar System, has been interpreted through competing formation models, including near-surface collapse, pure tectonic extension, and flexural subsidence related to the Tharsis volcanic load, yet the lack of direct seismic observations has prevented assessment of present-day state of stress in the crust. Here, we report the first seismic evidence of faulting within the Valles Marineris region. We analyze PP and SS body-wave phases from the farthest event from InSight, marsquake S0976a, which occurred near Valles Marineris. A single-station moment-tensor inversion reveals a robust strike-slip mechanism, with a P-axis subparallel to the canyon axis and a T-axis oriented orthogonally, indicating oblique shear on canyon-oblique faults and extension on canyon-parallel faults. Alternative source models for surface mass movements (e.g., landslides) and impact- or explosion-type sources fail to fit the observed waveforms, supporting a tectonic source at depth. The inferred source depth of ~40–42 km places the event in the mid- to lower crust, highlighting deep crustal deformation linked to inherited structural weaknesses from canyon formation. Stress reorganization between collapsed trough segments favors strike-slip faulting, consistent with geodynamic models and matching the mechanism of S0976a. These results provide the first direct seismological confirmation that Valles Marineris remains tectonically active and that its present-day deformation reflects long-lived, crustal-scale stresses retained from its formation.

Session: Planetary and Gravitational Wave Seismology [Poster]

Type: Poster

Date: 4/15/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Jung-Hun Song

Student Presenter: No

Invited Presentation: 

Poster Number: 140

Authors