Implications of longitudinal ridges for the mechanics of ice-free long runout landslides

• The thickness of terrestrial long runout landslides scales with the wavelength longitudinal ridges. Basal ice is not a necessary condition for formation ridges in landslides. Internal structures observed may point to vibration-assisted mechanism during landslide emplacement. are associated stress fluctuation, which qualitatively agree acoustic fluidization. Longitudinal spanning over 5 order magnitude can be generated, suggesting scale-independent mechanism. emplacement mechanisms across Solar System and their deposits remain subjects debate. similarity martian emplaced on suggests that an icy surface could explain both reduction friction deposition development However, laboratory experiments rapid granular flows show requirement ridges, instead form from convective cells within high-speed flows. These have shown (S) 2-3 times (T) flow, has also been demonstrated at field scale tens-of-kilometre landslide. Here, we present case study 4-km-long, ice-free El Magnifico Northern Chile exhibits clear first time S/T ratio agreement scaling relationship found previously measured Several outcrops allow us internal sections deposit shed light Our observations include interactions without chaotic mixing between different lithologies presence meters-sized blocks exhibit preserved original bedding discontinuities. We associate these fluctuations stress, as they similar numerically modelled slides, were suggested, some degree, results suggest 1) responsible scale- environment-independent; 2) while do necessarily support convective-style motion, interpretation deformation sliding mass derived pattern-forming vibrations. novel analysis provide important insights features Earth Mars discerning underlying run out