DOI: 10.5194/tc-14-1139-2020
论文题名: On the Green's function emergence from interferometry of seismic wave fields generated in high-melt glaciers: Implications for passive imaging and monitoring
作者: Sergeant A. ; Chmiel M. ; Lindner F. ; Walter F. ; Roux P. ; Chaput J. ; Gimbert F. ; Mordret A.
刊名: Cryosphere
ISSN: 19940416
出版年: 2020
卷: 14, 期: 3 起始页码: 1139
结束页码: 1171
语种: 英语
英文关键词: ambient noise
; environmental monitoring
; glacier dynamics
; imaging method
; numerical method
; seismic wave
; seismogram
; snowmelt
; wave field
; wave scattering
; Arctic
; Argentiere Glacier
; Auvergne-Rhone-Alpes
; France
; Greenland
; Greenland Ice Sheet
; Haute Savoie
英文摘要: Ambient noise seismology has revolutionized seismic characterization of the Earth's crust from local to global scales. The estimate of Green's function (GF) between two receivers, representing the impulse response of elastic media, can be reconstructed via cross-correlation of the ambient noise seismograms. A homogenized wave field illuminating the propagation medium in all directions is a prerequisite for obtaining an accurate GF. For seismic data recorded on glaciers, this condition imposes strong limitations on GF convergence because of minimal seismic scattering in homogeneous ice and limitations in network coverage. We address this difficulty by investigating three patterns of seismic wave fields: A favorable distribution of icequakes and noise sources recorded on a dense array of 98 sensors on Glacier d'Argentière (France), a dominant noise source constituted by a moulin within a smaller seismic array on the Greenland Ice Sheet, and crevasse-generated scattering at Gornergletscher (Switzerland). In Glacier d'Argentière, surface melt routing through englacial channels produces turbulent water flow, creating sustained ambient seismic sources and thus favorable conditions for GF estimates. Analysis of the cross-correlation functions reveals non-equally distributed noise sources outside and within the recording network. The dense sampling of sensors allows for spatial averaging and accurate GF estimates when stacked on lines of receivers. The averaged GFs contain high-frequency (>30 Hz ) direct and refracted P waves in addition to the fundamental mode of dispersive Rayleigh waves above 1 Hz . From seismic velocity measurements, we invert bed properties and depth profiles and map seismic anisotropy, which is likely introduced by crevassing. In Greenland, we employ an advanced preprocessing scheme which includes match-field processing and eigenspectral equalization of the cross spectra to remove the moulin source signature and reduce the effect of inhomogeneous wave fields on the GFs. At Gornergletscher, cross-correlations of icequake coda waves show evidence for homogenized incident directions of the scattered wave field. Optimization of coda correlation windows via a Bayesian inversion based on the GF cross coherency and symmetry further promotes the GF estimate convergence. This study presents new processing schemes on suitable array geometries for passive seismic imaging and monitoring of glaciers and ice sheets. © 2019 Cambridge University Press. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164584
Appears in Collections: 气候变化与战略
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作者单位: Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zürich, Zürich, Switzerland; Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, Grenoble, 38000, France; Department of Geological Sciences, University of Texas El Paso, El Paso, TX, United States; Université Grenoble Alpes, CNRS, IGE, Grenoble, France; Massachusetts Institute of Technology, Boston, MA, United States; Aix Marseille Univ, CNRS, Centrale Marseille, LMA, France
Recommended Citation:
Sergeant A.,Chmiel M.,Lindner F.,et al. On the Green's function emergence from interferometry of seismic wave fields generated in high-melt glaciers: Implications for passive imaging and monitoring[J]. Cryosphere,2020-01-01,14(3)