Imaging the Spatial and Temporal Evolution of Frictional Asperities Along the Failure Surface of Creeping Landslides to Illuminate the Mechanics of landslide Friction

有些滑坡会持续数年或数十年。在其他情况下，蠕变看起来类似，然后突然转变为灾难性的失败。区分这两种情况对于减轻滑坡危害至关重要。然而，滑坡摩擦的机制起源仍然不清楚，这限制了我们对滑坡如何，何时以及为什么有时会灾难性地加速，而其他滑坡则会持续数十年。该项目将通过结合两个不同地点的变形测量和地震学来促进对滑坡摩擦的理解，这两个地点最有可能代表上述两种情况。一个是经过充分研究的缓慢滑坡（加州的橡树岭土流），而另一个是最近在阿拉斯加哥伦比亚冰川附近发现的缓慢滑坡。尽管近一个世纪以来，橡树岭的土流一直表现出缓慢的滑动，但哥伦比亚不稳定性所处的环境，研究人员预计，冰川对斜坡的首次变形将导致加速，并可能导致灾难性的破坏。该项目对评估和减轻自然灾害有影响。该团队将制作一部简短的科学纪录片，绘制一张威廉王子湾的公共地图，在州和联邦机构之间进行协调，并培训一名博士生。这个项目的目的是促进理解为什么在滑坡中的摩擦凸起有时会灾难性地合并，而另一些则保持不同，尽管有削弱速度的摩擦，但仍允许蠕变数十年。目前，在时间和空间尺度上对滑坡的监测很少，而这需要更清楚地阐明滑坡摩擦的机制。这个项目的目标是通过结合变形监测和地震学来弥补这一差距，这些地震学研究和仪器都很好地研究了缓慢的滑坡（加州的橡树岭泥石流）和阿拉斯加哥伦比亚冰川附近的早期基岩破坏。尽管橡树岭的泥石流在近一个世纪以来一直表现出稳定的蠕变，但哥伦比亚冰川遗址所处的环境中，由于冰川的首次变形，斜坡可能会加速，这种加速可能导致灾难性的失败。实地部署将侧重于成像滑移和微地震活动在两种情况下的时空演变，以便1)在橡树岭测试两种不同模型之间的摩擦蠕变与粘滑运动在滑坡中的可能性，2)了解哥伦比亚冰川由于冰川首次变形导致蠕变加速，速度减弱的岩石是如何增长的，这一过程有时会导致灾难性的失败。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Some landslides creep steadily for years or decades. In others, the creep appears similar, then abruptly transitions to catastrophic failure. Distinguishing these two scenarios is crucial for landslide hazard mitigation. However, the mechanistic origins of landslide friction remain unclear, which limits our understanding of how, when, and why landslides sometimes accelerate catastrophically, whereas others creep for decades. This project will advance understanding of landslide friction by combining deformation measurements and seismology at two distinct sites that most likely represent the two scenarios above. One is a well-studied slow landslide (Oak Ridge earthflow in California), while the other is a newly identified slow landslide near Columbia Glacier in Alaska. Whereas Oak Ridge earthflow has exhibited slow sliding for nearly a century, the Columbia Instability is in a setting where the investigators expect that glacier debuttressing of the slope will lead to acceleration and possibly catastrophic failure. The project has implications for natural hazard assessment and mitigation. The team will produce a short science documentary, create a public map of Prince William sound, coordinate among state and federal agencies, and train one PhD student.This project aims to advance understanding of why frictional asperities in landslides sometimes coalesce catastrophically, whereas others remain distinct, permitting creep for decades despite velocity-weakening friction. Currently there is very little monitoring of landslides over the temporal and spatial scales that would be required to more clearly illuminate the mechanics of landslide friction. This project will aim to bridge this gap by combining deformation monitoring and seismology at a well-studied and well-instrumented slow landslide (Oak Ridge earthflow in California) and an incipient bedrock failure near Columbia Glacier in Alaska. Whereas Oak Ridge earthflow has exhibited stable creep for nearly a century, the Columbia glacier site is in a setting where the slope will likely undergo acceleration due to glacial debuttressing, and this acceleration may lead to catastrophic failure. Field deployments will focus on imaging the spatial and temporal evolution of slip and micro-seismicity in two settings in order to 1) test at Oak Ridge between two different models for how frictional creep associated with stick-slip motion is possible in landslides, and 2) understand at Columbia glacier how velocity weakening asperities grow as creep accelerates due to glacial debuttressing - a process that sometimes culminates in catastrophic failure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.