Black Rapids Glacier time-lapse photos, Eastern Alaska Range, 2012-2013

A glacier surge is characterized by a sudden increase in speed by one to two orders of magnitude and often leads to a significant movement of the terminus of the glacier. While the role of subglacial hydraulics during the surge has been well documented, the issue of surge initiation has remained unsolved. Also, the related question of why some glaciers surge and others do not remains open. This data set supported work to investigate whether the special geometry of many Alaska Range glaciers allows particularly large shear stresses to develop that eventually allow a surge to occur. The work focused on the Black Rapids Glacier on the Denali Fault in the eastern Alaska Range. This data set contains time lapse photos collected at three sites to document the filling and draining of ice-marginal lakes. These lakes drain annually to the glacier bed and lubricate it, leading to a glacier speed-up by a factor of two or three that can last more than a day. Such events act like mini-surges. Particular emphasis is placed on the reaction of tributary glaciers to a speed-up of the main branch.

冰川涌流（glacier surge）的典型特征为流速骤增1至2个数量级，且常引发冰川末端发生显著位移。尽管冰川涌流期间冰下水力作用（subglacial hydraulics）的功能已得到充分证实，但冰川涌流的触发机制始终是未解难题；另有相关问题悬而未决：为何部分冰川会发生涌流，而其余冰川则不会。本数据集支撑了一项探究工作，旨在厘清阿拉斯加山脉（Alaska Range）多数冰川的特殊几何形态是否会催生极强的剪切应力，进而最终引发冰川涌流。该研究聚焦于阿拉斯加山脉东部德纳里断层（Denali Fault）上的黑急流冰川（Black Rapids Glacier）。本数据集包含在三个观测点位采集的延时摄影照片（time lapse photos），用于记录冰缘湖（ice-marginal lakes）的充水与排水过程。这类冰缘湖每年会向冰川床排水，对冰川床起到润滑作用，使得冰川流速提升2至3倍，该提速状态可持续一天以上，此类事件类似于微型冰川涌流。研究特别关注了支流冰川对主支冰川提速的响应情况。