9D (2022-2026): Imaging the spatial and temporal evolution of frictional asperities along the failure surface of creeping landslides

• UC Santa Cruz, United States of America

This proposal will explore the question of what divides landslides that creep stably for decades from those where creep transitions to catastrophic failure. Like faults, landslides exhibit frictional slip with a diversity of deformation styles ranging from apparently stable slow sliding to catastrophic failure. However, whereas experimentally derived friction laws provide mechanistically-based explanations for similarly diverse behavior on faults, there is still no consensus about the appropriate constitutive relationship that governs slow landslide motion and hence its transition to catastrophic failure. 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 slow landslide friction. In this proposal, we 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 failure near Columbia Glacier in Alaska. The slope above Columbia Glacier is experiencing rapid debuttressing, a process that is likely to peak in the coming few years, potentially leading to catastrophic failure. At both locations, we aim to image the spatial and temporal evolution of frictional asperities during slow frictional slip. However, whereas Oak Ridge earthflow has exhibited stable creep for nearly a century, the Columbia glacier site is in a setting where we expect that the slope will undergo acceleration, and this acceleration may lead to catastrophic failure.

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