Inventory of young mass wasting events in Mars' Southern Hemisphere: Insights into characterization and formation mechanisms

Landslides are key geomorphic features on Mars that record past climate conditions, slope stability, and volatile-driven processes. We present a regional inventory of 290 landslides between 20°S and 50°S on Mars, focusing on Late Amazonian events underrepresented in global databases. To map landslides, we used high-resolution Context Camera (CTX) (5 m/px) satellite imagery, and detailed morphometric analyses were performed using stereo-derived CTX Digital Elevation Models (DEMs) (6 m/px) satellite. The mapped landslides were classified into three major types: rock avalanches, slumps, and ejecta-type features. Our results indicate that landslide areas range from 0.26 to 174 km², with estimated volumes between 0.003 and 5.72 km³. The height-to-length (H/L) ratios, varying from 0.00013 to 0.268, reveal substantial differences in mobility and formation mechanisms. Approximately 40% of landslides at high southern latitudes display morphologies suggestive of basal ice lubrication or cryosphere involvement, supporting ice-facilitated movement mechanisms. Crater size-frequency distribution (CSFD) analysis constrains absolute model ages of these landslides between 3.50 and 480 Ma (Middle to Late Amazonian), indicating repeated mass-wasting activity over extended geological timescales.

Spatial correlation analyses between landslides and glacial features such as Lineated Valley Fill (LVF), Lobate Debris Aprons (LDA), and Concentric Crater Fill (CCF) reveal a strong association between ice-bearing terrains and enhanced landslide mobility. These findings indicate that subsurface ice acted as both a stabilizing and lubricating agent, reducing basal friction while promoting high mobility under favourable thermal conditions.

These results provide the first comprehensive dataset of southern mid-latitude landslides, filling a major gap in Martian landslide inventories. The morphometric variability observed in this region demonstrates that cryosphere-substrate interactions play a crucial role in shaping Martian slope processes. Our findings underscore the complexity of mass wasting dynamics and their strong linkage to past climate fluctuations, providing new constraints on the timing and preservation conditions of buried ice deposits across Mars' recent geological history.