Controls on the Global Distribution of Martian Landslides

Abstract

Recent acquisition of high‐resolution satellite imagery of the Martian surface has permitted landslides to be studied on a global scale on Mars for the first time. We apply the Scoops3D software package to compute slope stability for select regions of the Martian surface, combining calculations of slope stability with number of observed landslides (Crosta, Frattini, et al., 2018; Crosta, De Blasio, et al., 2018), as reported in a recently published inventory of Martian landslides, to understand controls on the global distribution of landslides on Mars. We find that the distribution of landslides does not simply follow the distribution of unstable slopes. In particular, there is an abundance of landslides around Tharsis, and especially in Valles Marineris and Noctis Labyrinthus, which is not explained by an abundance of unstable topography alone. We analyzed for but did not find a clear large‐scale lithologic or stratigraphic control on landslide occurrence from subsurface heterogeneities. Other possibilities to explain the increased occurrence of landslides in Tharsis include (1) thin weak unit(s) that is regionally widespread and at multiple stratigraphic levels, such as from interbedded ashes; (2) seismic activity related to the Tharsis's geological activity, and (3) possible groundwater near Valles Marineris into the Amazonian. Given the apparently young ages of many landslide deposits in Valles Marineris (Quantin et al., 2004), continued modern day analysis of lithologies in Valles Marineris and observations of Martian seismicity may act to strengthen or rebut the first two hypotheses.