The Role of Massive Ice and Exposed Headwall Properties on Retrogressive Thaw Slump Activity
The Role of Massive Ice and Exposed Headwall Properties on Retrogressive Thaw Slump Activity
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DOI：
10.1029/2022jf006602
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发表时间：
2022-01
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影响因子：
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通讯作者：
S. Hayes;M. Lim;Paul Mann;D. Whalen;P. Fraser;R. Penlington;James E. Martin
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作者：
S. Hayes;M. Lim;Paul Mann;D. Whalen;P. Fraser;R. Penlington;James E. Martin
倒退解冻塌陷（RTS）是一种高度动态的大规模浪费形式，正在加速冰芯永久冻土地区的地貌变化，但对其活动的主要控制却很少受到限制。对环境敏感的大块冰体的空间变异性问题以及高时空分辨率地形数据的缺乏限制了我们预测其发展和更广泛影响的能力。这项研究通过调查半岛点的 RTS 过程来解决这些关键问题，半岛点是加拿大西部北极地区沉积物内大块冰的经过充分研究的地点。利用 2016 年、2017 年和 2018 年无人机勘测的高分辨率地形数据，我们 (a) 测量端盘特性和后退率的时间和空间变化，(b) 使用被动地震监测确定地下分层的空间模式，(c) 结合这些数据来分析和背景化控制端盘后退 (HWR) 率的因素。我们发现端墙特性，即大量冰和覆盖层厚度，是对 HWR 速率的重要控制。当端墙内陆存在持续大量冰暴露时，无论厚度如何，并且覆盖层厚度保持<4 m，HWR通常是其他端墙的两倍以上。此外，通过结合摄影测量和被动地震数据创建了 3D 场地模型，突出了内部分层的可变性，并证明了基于端墙曝光的内部分层外推的局限性。这些结果为 HWR 速率的现场控制提供了新的见解，并为了解其变异性提供了新方法。
Retrogressive Thaw Slumps (RTSs), a highly dynamic form of mass wasting, are accelerating geomorphic change across ice‐cored permafrost terrain, yet the main controls on their activity are poorly constrained. Questions over the spatial variability of environmentally sensitive massive ice bodies and a paucity of high‐spatial and temporal resolution topographic data have limited our ability to project their development and wider impacts. This research addresses these key problems by investigating RTS processes on Peninsula Point—a well‐studied site for intra‐sedimental massive ice in the Western Canadian Arctic. Utilizing high‐resolution topographic data from drone surveys in 2016, 2017 and 2018 we (a) measure the temporal and spatial variations in headwall properties and retreat rates, (b) determine the spatial pattern of subsurface layering using passive seismic monitoring and (c) combine these to analyze and contextualize the factors controlling headwall retreat (HWR) rates. We find that headwall properties, namely massive ice and overburden thickness, are significant controls over rates of HWR. Where persistent massive ice exposures are present inland of the headwall, regardless of thickness, and overburden thickness remains <4 m, HWR is typically more than double that of other headwalls. Furthermore, a 3D site model was created by combining photogrammetric and passive seismic data, highlighting internal layering variability and demonstrating the limitations of extrapolations of internal layering based on headwall exposures. These results provide fresh insights into the in situ controls on HWR rates and new approaches to understanding their variability.