Observation of surface features on an active landslide, and implications for understanding its history of movement
Observation of surface features on an active landslide, and implications for understanding its history of movement
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DOI：
10.5194/nhess-3-569-2003
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发表时间：
2003-12
影响因子：
4.6
通讯作者：
M. Parise
中科院分区：
文献类型：
--
作者：
M. Parise
抽象的。地表地貌是活动滑坡内部变形的结果，并在运动中不断地产生和破坏。观察它们的存在和分布，并对它们的演变进行调查，可以为以不同行为为特征的部门的群众运动的分区提供洞察。本研究分析和描述了科罗拉多州西南部圣胡安山脉活跃的物质运动--贫民窟泥石流--观测到的一些地表特征。贫民窟泥石流是世界上最著名和最壮观的滑坡之一；它由一个更年轻的活跃部分组成，它在更老的、更大的、不活跃的部分上移动。泥石流总长6.8公里，预计流量170×106m~3。其几乎恒定的移动速度(从头部每年约2米，到狭窄和中心部分每年最大6-7米，到活动脚趾每年1.3-2米)和移动物质的地质性质，非常适合观察地表特征的发展和演变。在过去的11年里，通过识别地面特征、测量其主要特征和详细测绘，对贫民窟遗址进行了重复测量。通过对比这段时间内观测到的泥石流特征，分析了崩塌泥石流的两个区段，并对发生的变化进行了评价：活动脚趾和位于滑坡左翼的区域。在第一种情况下，行业的选择取决于特定的流动活动和附近存在危险因素(高速公路位于距脚趾只有250米的下坡)；在第二种情况下，取决于许多地表特征的存在，大多由几代侧脊组成。滑坡活动的脚趾以连续运动为特征，这决定了地表特征的存在和分布经常发生变化，这一点从那里进行的多年观测中得到了证明。此外，对活动脚趾前面的非活动材料的监测显示，该区域正在经历脚趾前进造成的变形。另一方面，对活跃的贫民窟滑坡最窄和中心部分不同世代的侧脊的测绘和解释证明，大规模运动逐渐缩小，并伴随着参与滑坡的物质厚度的减少。通过多次观测贫民窟的地表地貌，可以重建特定地段的泥石流运动演变情况。这种低成本方法的唯一要求是提供详细的地形图和重复测量，因此，对于更好地了解活跃的质量运动的运动学，以及为了设计更适当的稳定工程，这种方法特别有用。
Abstract. Surface features are produced as a result of internal deformation of active landslides, and are continuously created and destroyed by the movement. Observation of their presence and distribution, and surveying of their evolution may provide insights for the zonation of the mass movement in sectors characterized by different behaviour. The present study analyses and describes some example of surface features observed on an active mass movement, the Slumgullion earthflow, in the San Juan Mountains of southwestern Colorado. The Slumgullion earthflow is one of the most famous and spectacular landslides in the world; it consists of a younger, active part which moves on and over an older, much larger, inactive part. Total length of the earthflow is 6.8 km, with an estimated volume of 170 × 10 6 m 3 . Its nearly constant rate of movement (ranging from about 2 m per year at the head, to a maximum of 6–7 m per year at its narrow and central part, to values between 1.3 and 2 m per year at the active toe), and the geological properties of moving material, are well suited for the observation of the development and evolution of surface features. In the last 11 years, repeated surveying at the Slumgullion site has been performed through recognition of surface features, measurements of their main characteristics, and detailed mapping. In this study, two sectors of the Slumgullion earthflow are analysed through comparison of the features observed in this time span, and evaluation of the changes occurred: they are the active toe and an area located at the left flank of the landslide. Choice of the sectors was dictated in the first case, by particular activity of movement and the nearby presence of elements at risk (highway located only 250 m downhill from the toe); and in the second case, by the presence of many surface features, mostly consisting of several generations of flank ridges. The active toe of the landslide is characterized by continuous movement which determines frequent variations in the presence and distribution of surface features, as evidenced by the multi-year observations there performed. In addition, monitoring of the inactive material just ahead of the active toe showed that this sector is experiencing deformation caused by the advancing toe. Mapping and interpretation of the different generations of flank ridges at the narrowest and central part of the active Slumgullion landslide evidenced, on the other hand, the gradual narrowing of the mass movement, which was accompanied by a reduction in the thickness of the material involved in landsliding. Multi-time observation of the surface features at the Slumgullion earthflow allowed to reconstruct the evolution of specific sectors of the mass movement. This low-cost approach, whose only requirements are the availability of a detailed topographic map, and repeated surveying, is therefore particularly useful to better understand the kinematics of active mass movements, also in order to design the more appropriate stabilization works.