Microseismicity, induced by the sliding of a glacier over its bed, can be used to characterize frictional properties of the ice‐bed interface, which are a key parameter controlling ice stream flow. We use naturally occurring seismicity to monitor spatiotemporally varying bed properties at Rutford Ice Stream, West Antarctica. We locate 230,000 micro‐earthquakes with local magnitudes from −2.0 to −0.3 using 90 days of recordings from a 35‐station seismic network located ∼40 km upstream of the grounding line. Events exclusively occur near the ice‐bed interface and indicate predominantly flow‐parallel stick‐slip. They mostly lie within a region of interpreted stiff till and along the likely stiffer part of mega‐scale glacial lineations. Within these regions, micro‐earthquakes occur in spatially (<100 m radius) and temporally (mostly 1–5 days activity) restricted event‐clusters (up to 4,000 events), which exhibit an increase, followed by a decrease, in event magnitude with time. This may indicate event triggering once activity is initiated. Although ocean tides modulate the surface ice flow velocity, we observe little periodic variation in overall event frequency over time and conclude that water content, bed topography and stiffness are the major factors controlling microseismicity. Based on variable rupture mechanisms and spatiotemporal characteristics, we suggest the event‐clusters relate to three end‐member types of bed deformation: (1) continuous creation and seismogenic destruction of small‐scale bed‐roughness, (2) ploughed clasts, and (3) flow‐oblique deformation during landform formation or along bedrock outcrops. This indicates that multiple processes, simultaneously active during glacial sliding, can accommodate stick‐slip behavior and that the bed continuously reorganizes.

中文翻译：

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并非所有的冰灾都是一样的：基础冰震表明南极西部拉特福德冰河层的多种床层变形机制

由冰川在其床上滑动所引起的微震可用于表征冰床界面的摩擦特性，这是控制冰流流动的关键参数。我们使用自然发生的地震活动来监测南极西部拉特福德冰溪的时空变化床层特性。我们利用位于接地线上游约40 km处的35个台站的地震网络的90天记录，找到了230,000个局部地震，震级范围从-2.0到-0.3的微地震。事件仅发生在冰床界面附近，并且主要表示平行流动。它们大多位于大型冰川界线可能被解释的坚硬区域内，并可能沿着较坚硬的部分。在这些区域内，微地震发生在空间上（< 半径为100 m的事件）和时间上（最多活动1至5天）受限制的事件簇（最多4,000个事件），随着时间的推移，事件量呈增加趋势，然后呈下降趋势。一旦活动开始，这可以指示事件触发。尽管海洋潮汐调节了表层冰的流速，但我们观察到整个事件频率随时间几乎没有周期性变化，并得出结论，含水量，河床地形和刚度是控制微地震的主要因素。基于可变的破裂机制和时空特征，我们建议事件群与床层变形的三种终端成员类型有关：（1）小规模床面粗糙度的连续形成和地震破坏;（2）犁屑;以及（ 3）地貌形成过程中或沿基岩露头的斜流变形。