Tidal and seasonal variations in calving flux observed with passive seismology
Tidal and seasonal variations in calving flux observed with passive seismology
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用被动地震学观测到的崩解通量的潮汐和季节变化
DOI：
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M. Truffer
中科院分区：
文献类型：
--
作者：
T. Bartholomaus;C. Larsen;M. West;S. O’Neel;E. Pettit;M. Truffer
崩裂事件的地震特征，即崩裂冰震，提供了一个比其他方法更精确地检查崩裂变异性的机会。在这里，我们利用阿拉斯加州雅茨冰川的观测资料，描述了探测、定位和表征冰震的方法。我们将这些冰震记录与观测到的冰裂事件的一致、人工生成的记录结合起来，开发并验证了一个统计模型，通过该模型，我们可以从冰震的性质推断冰山的大小。我们发现，冰震持续时间是冰山大小的唯一最重要的预测指标。然后，我们将该模型应用于18个月的地震记录，发现夏季和秋季冰山崩解通量升高，隆冬期间崩解明显平静。产犊通量对半日潮期很敏感。在退潮和退潮期间，大型崩解事件的可能性要比涨潮和涨潮期间高10%，这与较深的水对冰川末端具有稳定作用的观点相一致。多种因素影响着最终导致冰山崩解的机械断裂的发生。在雅孜冰川，地震学使我们能够证明，在季节性时间尺度上，海底融化速度的变化是冰山崩解速度的主要控制因素。在每小时到每天的时间尺度上，冰川末端的正应力的潮汐调制揭示了冰川对近端应力场变化的非线性响应。
The seismic signatures of calving events, i.e., calving icequakes, offer an opportunity to examine calving variability with greater precision than is available with other methods. Here using observations from Yahtse Glacier, Alaska, we describe methods to detect, locate, and characterize calving icequakes. We combine these icequake records with a coincident, manually generated record of observed calving events to develop and validate a statistical model through which we can infer iceberg sizes from the properties of calving icequakes. We find that the icequake duration is the single most significant predictor of an iceberg's size. We then apply this model to 18 months of seismic recordings and find elevated iceberg calving flux during the summer and fall and a pronounced lull in calving during midwinter. Calving flux is sensitive to semidiurnal tidal stage. Large calving events are tens of percent more likely during falling and low tides than during rising and high tides, consistent with a view that deeper water has a stabilizing influence on glacier termini. Multiple factors affect the occurrence of mechanical fractures that ultimately lead to iceberg calving. At Yahtse Glacier, seismology allows us to demonstrate that variations in the rate of submarine melt are a dominant control on iceberg calving rates at seasonal timescales. On hourly to daily timescales, tidal modulation of the normal stress against the glacier terminus reveals the nonlinear glacier response to changes in the near‐terminus stress field.
使用地震波形振幅自动定位冰震的方法
影响因子：
2.9
作者：
Jones G
通讯作者：
Jones G
格陵兰岛北部洪堡冰川快速退缩的基础地形控制
影响因子：
3.4
作者：
Carr J
通讯作者：
Carr J