Cassandra Seltzer, Maria-Gema Llorens, Andrew J. Cross
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引用次数: 0
摘要
地震学越来越多地被用于推断冰川冰流的规模和方向。然而,间隙融水对地震特性的影响仍未得到很好的解释。在此,我们扩展了之前对温带冰层地震各向异性的研究,考虑了融水优先取向(MPO)的作用。我们使用 ELLE 数值工具箱模拟了 MPO 强度和取向可变的温带冰的微结构剪切变形,并计算了这些数值冰-熔体聚集体的有效地震特性。我们的模型表明,即使 3.5% 的熔体体积也足以使快速方向旋转 90°,使 Vp 各向异性增加 +110%,并使 Vs 各向异性改变 -9% 至 +36%。这些效应在应变速率≥3.17 × 10-12 s-1时尤为突出。因此,在冰快速排出的地区,MPO 可能会掩盖温带冰流的地球物理特征,因此对于了解冰的质量损失至关重要。
Meltwater Orientations Modify Seismic Anisotropy in Temperate Ice
Seismology is increasingly used to infer the magnitude and direction of glacial ice flow. However, the effects of interstitial meltwater on seismic properties remain poorly constrained. Here, we extend previous studies on seismic anisotropy in temperate ices to consider the role of melt preferred orientation (MPO). We used the ELLE numerical toolbox to simulate microstructural shear deformation of temperate ice with variable MPO strength and orientation, and calculated the effective seismic properties of these numerical ice-melt aggregates. Our models demonstrate that even 3.5% melt volume is sufficient to rotate fast directions by up to 90°, to increase Vp anisotropy by up to +110%, and to modify Vs anisotropy by −9 to +36%. These effects are especially prominent at strain rates ≥3.17 × 10−12 s−1. MPO may thus obscure the geophysical signatures of temperate ice flow in regions of rapid ice discharge, and is therefore pivotal for understanding ice mass loss.
期刊介绍:
Geophysical Research Letters (GRL) publishes high-impact, innovative, and timely research on major scientific advances in all the major geoscience disciplines. Papers are communications-length articles and should have broad and immediate implications in their discipline or across the geosciences. GRLmaintains the fastest turn-around of all high-impact publications in the geosciences and works closely with authors to ensure broad visibility of top papers.