气候变化领域集成服务门户(CCPortal): Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling

CCPortal

DOI	10.5194/tc-15-501-2021
	Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling
	Guillemot A.; Baillet L.; Garambois S.; Bodin X.; Helmstetter A.; Mayoraz R.; Larose E.
发表日期	2021
ISSN	19940416
起始页码	501
结束页码	529
卷号	15 期号:2
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).
英文关键词	cryosphere; modeling; rock glacier; seismic noise
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202319
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
推荐引用方式 GB/T 7714	Guillemot A.,Baillet L.,Garambois S.,et al. Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling[J],2021,15(2).
APA	Guillemot A..,Baillet L..,Garambois S..,Bodin X..,Helmstetter A..,...&Larose E..(2021).Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling.Cryosphere,15(2).
MLA	Guillemot A.,et al."Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling".Cryosphere 15.2(2021).