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| Titel |
The sensitivity of GNSS measurements in Fennoscandia to distinct three-dimensional upper-mantle structures |
| VerfasserIn |
H. Steffen, P. Wu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 1 ; Nr. 5, no. 1 (2014-06-30), S.557-567 |
| Datensatznummer |
250115287
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| Publikation (Nr.) |
 copernicus.org/se-5-557-2014.pdf |
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| Zusammenfassung |
The sensitivity of global navigation satellite system (GNSS) measurements in
Fennoscandia to nearby viscosity variations in the upper mantle is
investigated using a 3-D finite element model of glacial isostatic adjustment
(GIA). Based on the lateral viscosity structure inferred from seismic tomography
and the location of the ice margin at the last glacial maximum (LGM), the GIA
earth model is subdivided into four layers, where each of them contains an
amalgamation of about 20 blocks of different shapes in the central area. The
sensitivity kernels of the three velocity components at 10 selected GNSS
stations are then computed for all the blocks.
We find that GNSS stations within the formerly glaciated area are most
sensitive to mantle viscosities below and in its near proximity, i.e., within
about 250 km in general. However, this can be as large as 1000 km if the
stations lie near the center of uplift. The sensitivity of all stations to
regions outside the ice margin during the LGM is generally negligible. In
addition, it is shown that prominent structures in the second (250–450 km
depth) and third layers (450–550 km depth) of the upper mantle may be
readily detected by GNSS measurements, while the viscosity in the first
mantle layer below the lithosphere (70–250 km depth) along the Norwegian
coast, which is related to lateral lithospheric thickness variation there,
can also be detected but with limited sensitivity.
For future investigations on the lateral viscosity structure, preference
should be on GNSS stations within the LGM ice margin. But these stations can
be grouped into clusters to improve the inference of viscosity in a specific
area. However, the GNSS measurements used in such inversion should be
weighted according to their sensitivity. Such weighting should also be
applied when they are used in combination with other GIA data (e.g., relative
sea-level and gravity data) for the inference of mantle viscosity. |
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