Analysis and interpretation of vibroseis data from Kohnen Station, Antarctica


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rebecca.schlegel [ at ] awi.de

Abstract

In 2011/12 a shallow reflection seismic survey was carried out at Kohnen Station, East Antarctica. A small electrodynamic vibrator source (ElViS) was used to generate seismic waves to determine the physical properties of firn and shallow ice. Depth converted seismic data could be compared to a nearby ice core, radar and wide-angle seismic measurements. Possible reflections are superimposed by strong diving and surface waves, excited by the ElViS. However, a velocity-depth profile was obtained by the analysis of diving waves. Elastic moduli of firn were calculated using diving-wave velocities and densities derived from ice-core measurements. These elastic moduli, as well as the velocities were compared to elastic moduli derived from a finite element algorithm, based on ice-core data. The difference between field derived values and the model values were found to be within the uncertainty range. Neither the raw nor the processed data shows any signs of englacial reflections. However, the stacked data show aligned high amplitude signals, which were found to be caused by Rayleigh waves. Additionally, a high amplitude signal can be seen at 1.63 s two-way traveltime (TWT). The bed reflection causing this high amplitude signal could be ruled out. The bed reflection for this area was determined by wide-angle data at 1.44s TWT, corresponding to 2700m depth which is in agreement with the depth found in radar and ice-core data (Diez, 2013). The calculations in this work suggest that the signal in 1.63s TWT is possibly caused by a Rayleigh wave that is reflected at nearby containers, but further investigations are necessary. Results demonstrate the adaptability of the ElViS technique to determine physical properties of firn which highlights the potential of this novel technique to be used in future glaciological research. The results presented here may facilitate improvements for further studies.



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Thesis (Master)
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Not peer-reviewed
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Published
Eprint ID
42469
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Schlegel, R. (2016): Analysis and interpretation of vibroseis data from Kohnen Station, Antarctica Master thesis, University Bremen.


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