Highly variable friction and slip observed at Antarctic ice stream bed
Highly variable friction and slip observed at Antarctic ice stream bed
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DOI：
10.1038/s41561-023-01204-4
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发表时间：
2023-06
影响因子：
18.3
通讯作者：
T. Hudson;S. Kufner;A. Brisbourne;J. Kendall;A. Smith;R. Alley;R. Arthern;T. Murray
中科院分区：
文献类型：
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作者：
T. Hudson;S. Kufner;A. Brisbourne;J. Kendall;A. Smith;R. Alley;R. Arthern;T. Murray
冰川在下伏海床上的滑移是控制冰从陆地迁移到海洋的主要机制，加速滑移导致海平面上升。然而，人们对冰川滑移的了解仍然很少，观测限制也很少。在这里，我们使用被动地震观测来测量南极洲拉特福德冰流底部的摩擦剪应力和滑动，使用了100,000个重复的粘滑冰川。我们发现，基面剪应力和滑动速率的变化范围分别为104~107Pa.2~1.5 m/d。由于有效正应力和冰床界面材料的相应变化，摩擦和滑移在时间上随小时的数量级变化，在空间上超过10s米。我们的发现表明，冰床比目前冰流模型中假设的要复杂得多，基本有效正应力可能比之前认为的要高得多。我们的观测可以为冰动力学模式的基本边界条件提供约束。这对于限制南极洲冰块质量损失的主要贡献，从而减少海平面上升预测的不确定性至关重要。
The slip of glaciers over the underlying bed is the dominant mechanism governing the migration of ice from land into the oceans, with accelerating slip contributing to sea-level rise. Yet glacier slip remains poorly understood, and observational constraints are sparse. Here we use passive seismic observations to measure both frictional shear stress and slip at the bed of the Rutford Ice Stream in Antarctica using 100,000 repetitive stick-slip icequakes. We find that basal shear stresses and slip rates vary from 104to 107Pa and 0.2 to 1.5 m per day, respectively. Friction and slip vary temporally over the order of hours, and spatially over 10s of metres, due to corresponding variations in effective normal stress and ice–bed interface material. Our findings suggest that the bed is substantially more complex than currently assumed in ice stream models and that basal effective normal stresses may be significantly higher than previously thought. Our observations can provide constraints on the basal boundary conditions for ice-dynamics models. This is critical for constraining the primary contribution of ice mass loss in Antarctica and hence for reducing uncertainty in sea-level rise projections.