The formation mechanism of long run-out landslides on planetary bodies

山体滑坡不仅是整个太阳系固体上重要的景观形成过程，而且在地球上也代表着对生命和基础设施的自然危害。对于长时间（通常是数十公里）滑坡的发生和流动机制，人们了解得尤其少。已经提出了许多方法来解释长期滑坡的形成，包括但不限于：基础细粉末、间隙流体、孔隙流体压力、气穴、蒸汽产生和热加压、摩擦熔体、润滑、流化和动态破碎。在地球上，野外工作允许对长期滑坡沉积物进行现场调查，这可以揭示对形成机制的重要见解。在许多情况下，容纳大部分滑动位移的大型滑坡的滑动带或基面上都充满了流体。孔隙流体压力的大小可以通过携带部分覆岩和减小有效应力来降低滑动体的表观摩擦。滑坡体滑带内物料的摩擦加热和化学反应也会导致孔隙流体沿剪切带受压，通过分解或脱水滑带物料而产生超压流体，从而降低滑动的摩擦阻力。这种化学-热-孔隙-机械过程可以导致极高的滑动速度（10-100米/秒），并且可以解释异常大的跳动。例如，最近的研究表明，在地球上最大的空中滑坡——心脏山滑坡中，高滑移速度下的剪切加热可能导致热分解和二氧化碳的释放，即使在低角度剥离面上也会发生灾难性的滑移。然而，在地球上的岩石记录中调查这些沉积物可能会受到板块构造驱动的活跃地质过程的阻碍。因此，利用其他行星体是有用的，因为那里的地质活动率较低，沉积物保存得更好。在火星上，有大量长期存在的滑坡，它们的形成机制也存在类似的不确定性，但它们在确定关键地质过程的年代方面也很重要。一些研究提出了脱水控制巨大的火星滑坡的开始和机制。这种滑坡的规模可以在火星的水手谷看到。在月球上，一个长期的滑坡被认为是由遥远的第谷撞击事件的喷出物引发的，它已被用作通过陨石坑大小频率分析确定行星表面年龄的关键校准点。这个项目将解决滑坡在地球、月球和火星上开始和传播多久的问题。这将包括陆地沉积物的现场分析，以及月球和火星的最新高分辨率遥感数据（例如LROC、HiRISE），以及开发。在阿波罗17号任务期间，联合主管施密特还在月球上的金牛座-利特罗山谷的一个研究滑坡中进行了实地调查。

Landslides are not only an important landscape-forming process on solid bodies throughout the Solar System, but on Earth also represent a natural hazard to life and infrastructure. The mechanisms responsible for the onset and flow of long run-out (typically tens of km) landslides are particularly poorly understood. Numerous methods have been proposed to explain long run-out landslide formation, including, but not limited to: basal fine powders, interstitial fluids, pore fluid pressure, air pockets, steam generation and thermal pressurisation, frictional melts, lubrication, fluidization and dynamic fragmentation.On Earth, fieldwork allows the in situ investigation of long run-out landslide deposits, which can reveal important insights into the formation mechanism. The slipping zone, or basal plane, of large landslides that accommodates much of the slip displacement is, in many cases, saturated with fluid. The amount of pore fluid pressure can lower the apparent friction of the sliding mass by carrying some of the overburden and reducing the effective stress. Frictional heating and chemical reactions of materials in the landslide slip zone can also lead to pressurization of the pore fluid along the shear zone and reduce the frictional resistance to sliding, by decomposing or dehydrating slip zone material and produce overpressured fluids. This chemical-thermal-poro-mechanical process can lead to extremely high sliding velocity (10-100 m/sec) and can explain the anomalously large runouts. For example, recent studies showed that at the Heart Mountain landslide, the largest sub-aerial landslide on Earth, shear heating at high slip velocities could have caused thermal decomposition and the release of carbon dioxide, which allowed catastrophic slip even on a low angle detachment surface. However, investigating these deposits in the rock record on Earth can be hampered by active geological processes driven by plate tectonics. Therefore it is useful to use other planetary bodies, where deposits have been better preserved due to lower rates of geological activity.On Mars, there are a large number of long run-out landslides that suffer from a similar uncertainty in formation mechanism , but which are also important in dating key geological processes. Some studies have proposed dehydration controls on the initiation and mechanics of enormous Martian landslides. The scale of such landslides can be seen in Valles Marineris, Mars. On the Moon, a long run-out landslide, thought to be triggered by ejecta from the distant Tycho impact event, has been used as a key calibration point in age dating planetary surfaces through crater size-frequency analysis. This project will address the question of how long run-out landslides initiate and propagate on Earth, the Moon and Mars. This will involve a combination of in situ analysis for terrestrial deposits, and the latest high-resolution remote sensing data (e.g. LROC, HiRISE) for the Moon and Mars, as well as developing. Co-supervisor Schmitt also carried out fieldwork at one of the study landslides in the Taurus-Littrow valley on the Moon during the Apollo 17 mission.