Lateral viscosity variations and post-glacial rebound: effects on present-day VLBI baseline deformations

By means of a finite element algorithm we investigate the effects of lateral viscosity variations upon the horizontal motions currently detected by VLBI techniques in Europe. Our axisymmetric flat models, appropriate to describe the rebound due to the melting of the Fennoscandia ice‐sheet, are chara...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: C. GIUNCHI, R. SABADINI, SPADA, GIORGIO
Other Authors: C., Giunchi, Spada, Giorgio, R., Sabadini
Format: Article in Journal/Newspaper
Language:English
Published: 1997
Subjects:
Engineering controlled terms: Algorithm
Deformation
Glacial geology
Glacier
Finite element method
Ice
Melting
Viscosity Continental collision
Finite element algorithm
Horizontal deformation
Horizontal motion
Post glacial rebound
Simple geometrie
Viscosity increase
Viscosity variations Engineering main heading: Viscosity
Glaciers Engineering uncontrolled terms: Baseline deformation
Lateral viscosity variation
Post-glacial rebound GEOBASE Subject Index: mantle
rheology
VLBI Regional Index: Europe
Fennoscandia
Ice Sheet
Online Access:http://hdl.handle.net/11576/1886065
https://doi.org/10.1029/96GL03773
http://onlinelibrary.wiley.com/doi/10.1029/96GL03773/full
Description
Summary:By means of a finite element algorithm we investigate the effects of lateral viscosity variations upon the horizontal motions currently detected by VLBI techniques in Europe. Our axisymmetric flat models, appropriate to describe the rebound due to the melting of the Fennoscandia ice‐sheet, are characterized by a layered compressible mantle with linear Maxwell rheology. We have first computed the time‐evolution of theoretical baselines characterized by a simple geometry. In agreement with previous results, the rates of horizontal deformation have been found to be greatly sensitive to both lateral viscosity variations and deep mantle stratification, especially for baselines located in the vicinity of the ice sheet margin. To complete our study, we have compared our numerical results with the observed time‐evolutions of relevant European baselines. Onsala‐Wettzell and Onsala‐Eflsberg are fitted by a laterally varying asthenosphere and sharp viscosity increase in the lower mantle; longer baselines, connecting these sites to Medicina (northern Italy), indicate that post glacial rebound is responsible only for a fraction of the VLBI observations, the residual being thus attributable to continental collision in the Mediterranean Sea.

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