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

Scaling Relationship Between the Wavelength of Longitudinal Ridges and the Thickness of Long Runout Landslides on the Moon

“…Figure 6b shows the S/T ratio values found at the six profiles and how they compare with results from previous studies (Magnarini et al, 2019(Magnarini et al, , 2021. The S/T ratio values obtained with the WAC-derived DEM fall within the range of the scaling relationship between the two parameters found in laboratory experiments on rapid granular flows, which is represented as the gray area: Profile 4 shows an S/T ratio of 2.25, Profile 5 shows an S/T ratio of 2.42, and Profile 6 shows an S/T ratio of 2.32.…”

“…On the other hand, the surface of the Tsiolkovskiy crater landslide shows prominent longitudinal ridges and furrows that stretch for almost the entire extent of the deposit (e.g., Boyce et al, 2020;El-Baz, 1972;Guest & Murray, 1969). These distinctive longitudinal structures are common in large-scale mass movements across the Solar System (e.g., Earth [Dufresne & Davies, 2009;Magnarini et al, 2021;Shreve, 1966]; the Moon [Boyce et al, 2020;Howard, 1973;Schmitt et al, 2017]; Mars [Lucchitta, 1979;Magnarini et al, 2019]; Ceres [Schmidt et al, 2017]; Iapetus [Singer et al, 2012]). However, the origin and the relationship with the emplacement of long runout landslides have been a matter of discussion (Figure 2), in particular whether they are linked to environmental conditions, such as the presence of friction reducing basal ice or clay minerals (De Blasio, 2011;Dufresne & Davies, 2009), or linked to mechanical instabilities within the rapid moving flow (Borzsonyi et al, 2009;Magnarini et al, 2019), or linked to the propagation of acoustic waves within the landslide (Magnarini et al, 2021).…”

“…Ice-free laboratory experiments on rapid granular flows (Borzsonyi et al, 2009;Forterre & Pouliquen, 2001) and studies of the martian Coprates Labes landslide (Magnarini et al, 2019) and the terrestrial El Magnifico landslide (Magnarini et al, 2021) have showed that the wavelength of the ridges is consistently 2 to 3 times 10.1029/2021JE006922 3 of 18 the thickness of the landslide deposit. In light of the debate about the formation mechanism of longitudinal ridges and the possible influence of an icy basal surface, the presence of longitudinal ridges in lunar landslides offers an ideal site to further investigate the recurrence of the scaling relationship between the wavelength of the ridges and the thickness of the landslide deposit on a planetary body that is considered to be ice-free throughout its geological time.…”

“…Dufresne andDavies (2009) andDe Blasio (2011) suggest that that longitudinal ridges are the result of the tensile deformation that landslides undergo during their emplacement over low friction surfaces, of which an icy surface is the favored condition. Instead, Magnarini et al (2019Magnarini et al ( , 2021 propose environment-independent mechanisms that rely on mechanical instability within the flow and pattern-forming acoustic waves propagating within the slide, respectively. Further description of these mechanisms can be found in Supporting Information S1.…”

“…In light of the debate about the formation mechanism of longitudinal ridges and the possible influence of an icy basal surface, the presence of longitudinal ridges in lunar landslides offers an ideal site to further investigate the recurrence of the scaling relationship between the wavelength of the ridges and the thickness of the landslide deposit on a planetary body that is considered to be ice-free throughout its geological time. Building on the study of (Magnarini et al, 2019(Magnarini et al, , 2021, here we use high resolution imagery and topographic datasets to conduct morphometric analysis of the Tsiolkovskiy crater landslide and the Light Mantle landslides. Dufresne andDavies (2009) andDe Blasio (2011) suggest that that longitudinal ridges are the result of the tensile deformation that landslides undergo during their emplacement over low friction surfaces, of which an icy surface is the favored condition.…”