Comparison of elastic moduli from seismic diving-wave and ice-core microstructure analysis in Antarctic polar firn

We compared elastic moduli in polar firn derived from diving wave refraction seismic velocity analysis, firn-core density measurements and microstructure modelling based on firn-core data. The seismic data were obtained with a small electrodynamic vibrator source near Kohnen Station, East Antarctica...

Full description

Bibliographic Details
Published in:Annals of Glaciology
Main Authors: Rebecca Schlegel, Anja Diez, Henning Löwe, Christoph Mayer, Astrid Lambrecht, Johannes Freitag, Heinrich Miller, Coen Hofstede, Olaf Eisen
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press 2019
Subjects:
Anisotropic ice
Antarctic glaciology
applied glaciology
polar firn
seismics
Meteorology. Climatology
QC851-999
Antarctic
East Antarctica
Kohnen
Kohnen Station
Annals of Glaciology
Antarc*
Antarctica
ice core
Online Access:https://doi.org/10.1017/aog.2019.10
https://doaj.org/article/6d4615c6d0514f449fde2de5c6e80528
Description
Summary:We compared elastic moduli in polar firn derived from diving wave refraction seismic velocity analysis, firn-core density measurements and microstructure modelling based on firn-core data. The seismic data were obtained with a small electrodynamic vibrator source near Kohnen Station, East Antarctica. The analysis of diving waves resulted in velocity–depth profiles for different wave types (P-, SH- and SV-waves). Dynamic elastic moduli of firn were derived by combining P- and S-wave velocities and densities obtained from firn-core measurements. The structural finite-element method (FEM) was used to calculate the components of the elastic tensor from firn microstructure derived from X-ray tomography of firn-core samples at depths of 10, 42, 71 and 99 m, providing static elastic moduli. Shear and bulk moduli range from 0.39 to 2.42 GPa and 0.68 to 2.42 GPa, respectively. The elastic moduli from seismic observations and the structural FEM agree within 8.5% for the deepest achieved values at a depth of 71 m, and are within the uncertainty range. Our observations demonstrate that the elastic moduli of the firn can be consistently obtained from two independent methods which are based on dynamic (seismic) and static (tomography and FEM) observations, respectively, for deeper layers in the firn below ~10 m depth.

Similar Items