Slope stability analysis of a west-facing landslide in the Iani Chaos Region (Mars)

Iani Chaos, located on the eastern margin of Margaritifer Terra, is one of the largest chaos terrains on Mars, where significant elevation contrasts have favoured gravitational mass-wasting processes. This study focuses on a west-facing landslide extending for 1.52 km2, with a mobilised volume of about 22.9 × 106 m3. The landslide volume was estimated by differencing the reconstructed pre-event surface from the post-event Digital Terrain Model (DTM). High Resolution Imaging Science Experiment (HiRISE) imagery and a stereo-derived DTM with a spatial resolution of 1 m/pixel, were used to delineate the main geomorphological features and to quantify the detachment and deposition zones. These datasets were also used to reconstruct the concave basal failure surface. The geotechnical input parameters, including material cohesion, internal friction angle, and unit weight derived from rover datasets and analogue studies. Mechanical properties of the involved materials were statistically processed to define realistic ranges ensuring that the assigned distributions closely reflect the values observed in Martian regolith. A probabilistic slope stability analysis was conducted using Rocscience™ Slide2 and the Bishop simplified method on the reconstructed failure surface. Under static conditions the slope exhibits stability, whereas under dynamic loading scenarios stability markedly decreases. The correlation analyses indicate that, within the range of geotechnical parameters experimented in this study, the internal friction angle has the main control on the modelled slope stability, whereas PGA represents the principal destabilising factor under pseudo-static conditions. For the investigated landslide, the results suggest that transient seismic loading could have acted as a possible trigger for slope failure.