Mass‐wasting features and processes in Vesta's south polar basin Rheasilvia

Otto, Katharina A.; Jaumann, R.; Krohn, Katrin; Matz, Klaus-Dieter; Preusker, Frank; Roatsch, Thomas; Schenk, P.; Scholten, F.; Stephan, K.; Raymond, C. A.; Russell, C. T.

doi:10.1002/2013je004333

Cited by 31 publications

(70 citation statements)

References 54 publications

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“…Their difference is within the range induced by the uncertainty of the estimate of the initial scar geometry 10 . This is an important result for the calibration of numerical models, indicating that an estimate of the friction coefficient needed to simulate real landslides can be readily obtained from equation (1).…”

Section: Resultsmentioning

confidence: 86%

“…They have also been observed on other planetary bodies of our Solar System, from the interior planets to the icy moons of Saturn as well as small bodies such as the asteroid Vesta 1 . On Earth these mass wasting processes feed rivers with solid materials and thus participate in the evolution of the landscape.…”

mentioning

confidence: 82%

“…This ratio shows a clear decrease with increasing volume, raising two types of questions: (1) What is the physical meaning of the Heim's ratio? Does it really represent the effective friction during the landslide?…”

mentioning

confidence: 99%

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Frictional velocity-weakening in landslides on Earth and on other planetary bodies

2014

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One of the ultimate goals in landslide hazard assessment is to predict maximum landslide extension and velocity. Despite much work, the physical processes governing energy dissipation during these natural granular flows remain uncertain. Field observations show that large landslides travel over unexpectedly long distances, suggesting low dissipation. Numerical simulations of landslides require a small friction coefficient to reproduce the extension of their deposits. Here, based on analytical and numerical solutions for granular flows constrained by remote-sensing observations, we develop a consistent method to estimate the effective friction coefficient of landslides. This method uses a constant basal friction coefficient that reproduces the first-order landslide properties. We show that friction decreases with increasing volume or, more fundamentally, with increasing sliding velocity. Inspired by frictional weakening mechanisms thought to operate during earthquakes, we propose an empirical velocity-weakening friction law under a unifying phenomenological framework applicable to small and large landslides observed on Earth and beyond.

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Section: Resultsmentioning

confidence: 86%

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confidence: 82%

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Frictional velocity-weakening in landslides on Earth and on other planetary bodies

2014

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“…The geology of the southern hemisphere is characterized by the impacts Rheasilvia and Veneneia: a central mound, a circular depression and large scale scarps are present Schenk et al, 2012). Mass wasting material has accumulated within the basins whereas ejecta material has been distributed and accumulated outside (Schenk et al, 2012;Otto et al, 2013). A unit containing troughs and ridges located at the equator is named the Divalia Fossae Formation and is possibly the result of the Rheasilvia impact Buczkowski et al, 2012).…”

Section: Datasets and Methodsmentioning

confidence: 99%

Geologic map of the northern hemisphere of Vesta based on Dawn Framing Camera (FC) images

Ruesch

Hiesinger

Blewett

et al. 2014

Icarus

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a b s t r a c tThe Dawn Framing Camera (FC) has imaged the northern hemisphere of the Asteroid (4) Vesta at high spatial resolution and coverage. This study represents the first investigation of the overall geology of the northern hemisphere (22-90°N, quadrangles Av-1, 2, 3, 4 and 5) using these unique Dawn mission observations. We have compiled a morphologic map and performed crater size-frequency distribution (CSFD) measurements to date the geologic units. The hemisphere is characterized by a heavily cratered surface with a few highly subdued basins up to $200 km in diameter. The most widespread unit is a plateau (cratered highland unit), similar to, although of lower elevation than the equatorial Vestalia Terra plateau. Large-scale troughs and ridges have regionally affected the surface. Between $180°E and $270°E, these tectonic features are well developed and related to the south pole Veneneia impact (Saturnalia Fossae trough unit), elsewhere on the hemisphere they are rare and subdued (Saturnalia Fossae cratered unit). In these pre-Rheasilvia units we observed an unexpectedly high frequency of impact craters up to $10 km in diameter, whose formation could in part be related to the Rheasilvia basin-forming event. The Rheasilvia impact has potentially affected the northern hemisphere also with S-N small-scale lineations, but without covering it with an ejecta blanket. Post-Rheasilvia impact craters are small (<60 km in diameter) and show a wide range of degradation states due to impact gardening and mass wasting processes. Where fresh, they display an ejecta blanket, bright rays and slope movements on walls. In places, crater rims have dark material ejecta and some crater floors are covered by ponded material interpreted as impact melt.

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“…It is unclear whether these are small impact melt flows originating from these craters, or more likely are distal ejecta from Marcia or perhaps the Rheasilvia basin. A more detailed study of mass wasting features in the Rheasilvia basin is presented by Otto et al (2013). Hyperspectral data from Dawn's Visible and Infrared Spectrometer (VIR, De Sanctis et al, 2011 provide additional information on some of Vesta's largest lobate flow-like units.…”

Section: Lobate Features From Gravity Driven Mass Movementsmentioning

confidence: 99%

Lobate and flow-like features on asteroid Vesta

Williams

O’Brien

Schenk

et al. 2014

Planetary and Space Science

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a b s t r a c tWe studied high-resolution images of asteroid Vesta's surface ( $ 70 and 20-25 m/pixel) obtained during the High-and Low-Altitude Mapping Orbits (HAMO, LAMO) of NASA's Dawn mission to assess the formation mechanisms responsible for a variety of lobate, flow-like features observed across the surface. We searched for evidence of volcanic flows, based on prior mathematical modeling and the well-known basaltic nature of Vesta's crust, but no unequivocal morphologic evidence of ancient volcanic activity has thus far been identified. Rather, we find that all lobate, flow-like features on Vesta appear to be related either to impact or erosional processes. Morphologically distinct lobate features occur in and around impact craters, and most of these are interpreted as impact ejecta flows, or possibly flows of impact melt. Estimates of melt production from numerical models and scaling laws suggests that large craters like Marcia ( $ 60 km diameter) could have potentially produced impact melt volumes ranging from tens of millions of cubic meters to a few tens of cubic kilometers, which are relatively small volumes compared to similar-sized lunar craters, but which are consistent with putative impact melt features observed in Dawn images. There are also examples of lobate flows that trend downhill both inside and outside of crater rims and basin scarps, which are interpreted as the result of gravity-driven mass movements (slumps and landslides).

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Mass‐wasting features and processes in Vesta's south polar basin Rheasilvia

Cited by 31 publications

References 54 publications

Frictional velocity-weakening in landslides on Earth and on other planetary bodies

Frictional velocity-weakening in landslides on Earth and on other planetary bodies

Geologic map of the northern hemisphere of Vesta based on Dawn Framing Camera (FC) images

Lobate and flow-like features on asteroid Vesta

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