Ice shapes the landslide landscape on Mars

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Nov 21, 2017.

  1. paddoboy Valued Senior Member

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    https://phys.org/news/2017-11-ice-landslide-landscape-mars.html

    How good is your Martian geography? Does Valles Marineris ring a bell? This area is known for having landslides that are among the largest and longest in the entire solar system. They make the perfect object of study due to their steep collapse close to the scarp, extreme thinning, and long front runout. In a new research paper published in EPJ Plus, Fabio De Blasio and colleagues from Milano-Bicocca University, Italy, explain the extent to which ice may have been an important medium of lubrication for landslides on Mars. This can in turn help us understand the geomorphological history of the planet and the environment of deposition.


    The authors noted that the landslides in Valles Marineris are of similar shape as ice-lubricated landslides on Earth. In their paper, they feed these observations, combined with remote sensing measurements showing the presence of massive ice under the soil, into a numerical simulation exploring the possibility that such landslides were lubricated by ice.



    Read more at: https://phys.org/news/2017-11-ice-landslide-landscape-mars.html#jCp
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    the paper:
    https://link.springer.com/article/10.1140/epjp/i2017-11727-x

    Modelling Martian landslides: dynamics, velocity, and paleoenvironmental implications:

    Abstract.
    Landslides on Mars exhibit features such as steep collapse, extreme deposit thinning, and long runout. We study the flow dynamics of Martian landslides particularly in Valles Marineris, where landslides are among the largest and longest. Firstly, we observe that landslides in Valles Marineris share a series of features with terrestrial landslides fallen onto glaciers. The presence of suspected glacial and periglacial morphologies from the same areas of Valles Marineris, and the results of remote sensing measurements suggest the presence of ice under the soil and into the rock slopes. Thus, we explore with numerical simulation the possibility that such landslides have been lubricated by ice. To establish a plausible rheological model for these landslides, we introduce two possible scenarios. One scenario assumes ice only at the base of the landslide, the other inside the rock-soil. A numerical model is extended here to include ice in these two settings, and the effect of lateral widening of the landslide. Only if the presence of ice is included in the calculations, do results reproduce reasonably well both the vertical collapse of landslide material in the scarp area, and the extreme thinning and runout in the distal area, which are evident characteristics of large landslides in Valles Marineris. The calculated velocity of landslides (often well in excess of 100 m/s and up to 200 m/s at peak) compares well with velocity estimates based on the run-up of the landslides on mounds. We conclude that ice may have been an important medium of lubrication of landslides on Mars, even in equatorial areas like Valles Marineris.
     
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  3. Gawdzilla Sama Registered Senior Member

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  5. paddoboy Valued Senior Member

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  7. paddoboy Valued Senior Member

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    https://phys.org/news/2017-11-recurring-martian-streaks-sand.html

    Recurring martian streaks: flowing sand, not water?

    Dark features on Mars previously considered evidence for subsurface flowing of water are interpreted by new research as granular flows, where grains of sand and dust slip downhill to make dark streaks, rather than the ground being darkened by seeping water.

    Continuing examination of these still-perplexing seasonal dark streaks with a powerful camera on NASA's Mars Reconnaissance Orbiter (MRO) shows they exist only on slopes steep enough for dry grains to descend the way they do on faces of active dunes.

    The findings published today in Nature Geoscience argue against the presence of enough liquid water for microbial life to thrive at these sites. However, exactly how these numerous flows begin and gradually grow has not yet been explained. Authors of the report propose possibilities that include involvement of small amounts of water, indicated by detection of hydrated salts observed at some of the flow sites.



    Read more at: https://phys.org/news/2017-11-recurring-martian-streaks-sand.html#jCp

    the paper:

    https://www.nature.com/articles/s41561-017-0012-5

    Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water

    Abstract

    Recent liquid water flow on Mars has been proposed based on geomorphological features, such as gullies. Recurring slope lineae — seasonal flows that are darker than their surroundings — are candidate locations for seeping liquid water on Mars today, but their formation mechanism remains unclear. Topographical analysis shows that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes. In Eos Chasma, linea lengths vary widely and are longer where there are more extensive angle-of-repose slopes, inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows. The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.
     

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