DOI: 10.5194/tc-15-501-2021
论文题名: Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling
作者: Guillemot A. ; Baillet L. ; Garambois S. ; Bodin X. ; Helmstetter A. ; Mayoraz R. ; Larose E.
刊名: Cryosphere
ISSN: 19940416
出版年: 2021
卷: 15, 期: 2 起始页码: 501
结束页码: 529
语种: 英语
英文关键词: cryosphere
; modeling
; rock glacier
; seismic noise
英文摘要: Among mountainous permafrost landforms, rock glaciers are mostly abundant in periglacial areas, as tongue-shaped heterogeneous bodies. Passive seismic monitoring systems have the potential to provide continuous recordings sensitive to hydro-mechanical parameters of the subsurface. Two active rock glaciers located in the Alps (Gugla, Switzerland, and Laurichard, France) have been instrumented with seismic networks. Here, we analyze the spectral content of ambient noise to study the modal sensitivity of rock glaciers, which is directly linked to the system's elastic properties. For both sites, we succeed in tracking and monitoring resonance frequencies of specific vibrating modes of the rock glaciers over several years. These frequencies show a seasonal pattern characterized by higher frequencies at the end of winters and lower frequencies in warm periods. We interpret these variations as the effect of the seasonal freeze-thawing cycle on elastic properties of the medium. To assess this assumption, we model both rock glaciers in summer, using seismic velocities constrained by active seismic acquisitions, while bedrock depth is constrained by ground-penetrating radar surveys. The variations in elastic properties occurring in winter due to freezing were taken into account thanks to a three-phase Biot-Gassmann poroelastic model, where the rock glacier is considered a mixture of a solid porous matrix and pores filled by water or ice. Assuming rock glaciers to be vibrating structures, we numerically compute the modal response of such mechanical models by a finite-element method. The resulting modeled resonance frequencies fit well the measured ones over seasons, reinforcing the validity of our poroelastic approach. This seismic monitoring allows then a better understanding of the location, intensity and timing of freeze-thawing cycles affecting rock glaciers. © 2021 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164697
Appears in Collections: 气候变化与战略
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作者单位: Laboratoire ISTerre, Univ. Grenoble Alpes, CNRS, Univ. Savoie Mont Blanc, Grenoble, 38000, France; Laboratoire EDYTEM, Univ. Grenoble Alpes, CNRS, Univ. Savoie Mont-Blanc, Chambéry, 73000, France; Services des Forêts des Cours d'Eau et du Paysage, Canton of Valais, Sion, 1951, Switzerland
Recommended Citation:
Guillemot A.,Baillet L.,Garambois S.,et al. Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling[J]. Cryosphere,2021-01-01,15(2)