New observations of topographic slumps in Valles Marineris, Mars: Investigating the role of recurring slope lineae

Abstract

Small-scale landslides, termed topographic slumps, are commonly co-located with seasonally active recurring slope lineae (RSL) on Mars. Previously identified topographic slumps initiated beneath or around the terminal points of RSL, suggesting that RSL activity may trigger slump formation. In this study, we conducted a comprehensive survey of HiRISE images spanning Mars years (MY) 29 to 37 in the southern mid-latitudes, northern mid-latitudes, and equatorial latitudes. We report eight newly identified topographic slumps that formed over the past 4 Mars years. Despite a comprehensive survey, these slumps were exclusively observed on slopes within Valles Marineris. While most of these slumps were co-located with RSL, two occurred on slopes lacking any detectable RSL activity. All slumps, however, formed on steep slopes (>27°) with inferred high sediment supply. We analyzed slump morphologies, seasonalities, and slope parameters to discuss potential topographic slump formation mechanisms. We suggest that if RSL are dry granular flows, gradual oversteepening due to debris accumulation beneath their termini could promote slumping. However, the limited number of topographic slumps relative to the widespread occurrence of RSL suggests that these features may be unrelated, or that unknown alternative conditions are necessary to initiate slump formation.