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

滑坡不仅是整个太阳系固体上一个重要的景观形成过程，而且在地球上也是对生命和基础设施的自然灾害。对长时间(通常为数十公里)滑坡的发生和流动的机制了解得特别少。已经提出了许多方法来解释长时间滑坡的形成，包括但不限于：基础微粉、间隙流体、孔隙流体压力、气囊、蒸汽产生和热加压、摩擦熔融、润滑、流态化和动态破碎。在地球上，野外工作可以对长时间滑坡沉积进行现场调查，这可以揭示形成机制的重要见解。在许多情况下，容纳了大部分滑动位移的大型滑坡的滑动带或基准面被流体饱和。孔隙流体压力的大小可以通过携带部分覆盖层、降低有效应力来降低滑动体的表观摩阻。滑坡滑带中物质的摩擦加热和化学反应还可导致沿剪切带的孔隙流体加压，降低滑动摩擦阻力，使滑带物质分解或脱水，产生超压流体。这种化学-热-孔隙-机械过程可能导致极高的滑动速度(10-100米/秒)，并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--心山滑坡中，高滑动速度的剪切加热可能会导致热分解和二氧化碳的释放，这使得即使在低角度滑脱表面也会发生灾难性的滑动。然而，研究地球上岩石记录中的这些矿床可能会受到板块构造驱动的活跃地质过程的阻碍。因此，使用其他行星体是有用的，因为较低的地质活动率使那里的沉积物得到了更好的保存。在火星上，有大量的长期滑坡，在形成机制上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，脱水作用可以控制火星巨大山体滑坡的形成和机制。在火星的水手谷可以看到这样的山体滑坡的规模。在月球上，一场长时间的滑坡被认为是由遥远的第谷撞击事件产生的喷射物引发的，它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、月球和火星上引发和传播多长时间的问题。这将涉及对陆地沉积物的现场分析和对月球和火星的最新高分辨率遥感数据(例如LROC、HiRISE)的结合，以及开发。在阿波罗17号任务期间，联合监督人施密特还在月球金牛座-利特洛山谷的一个山体滑坡研究中进行了实地工作。

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.