Articles | Volume 11, issue 4
https://doi.org/10.5194/se-11-1551-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/se-11-1551-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
26 Aug 2020
Research article |
| 26 Aug 2020
| 26 Aug 2020
Increased density of large low-velocity provinces recovered by seismologically constrained gravity inversion
Wolfgang Szwillus
CORRESPONDING AUTHOR
Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
Jörg Ebbing
Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
Bernhard Steinberger
Sektion 2.5: Geodynamische Modellierung, Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum, Potsdam, Germany
The Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway
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Subject area: Core and mantle structure and dynamics | Editorial team: Geodesy, gravity, and geomagnetism | Discipline: Geodesy
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Several alternative gravity modelling techniques and associated numerical codes with their own advantages and limitations are available for the solid Earth community. With upcoming state-of-the-art lithosphere density models and accurate global gravity field data sets, it is vital to understand the differences of the various approaches. In this paper, we discuss the four widely used techniques: spherical harmonics, tesseroid integration, triangle integration, and hexahedral integration.
Marc Rovira-Navarro, Wouter van der Wal, Valentina R. Barletta, Bart C. Root, and Louise Sandberg Sørensen
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The Barents Sea and Fennoscandia were home to large ice sheets around 20 000 years ago. After the melting of these ice sheets, the land slowly rebounded. The rebound speed is determined by the viscosity of the deep Earth. The rebound is ongoing and causes small changes in the Earth’s gravity field, which can be measured by the GRACE satellite mission. We use these measurements to obtain the viscosity of the upper mantle and find that it is 2 times higher in Fennoscandia than in the Barents Sea.
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Short summary
At the bottom of the mantle (2850 km depth) two large volumes of reduced seismic velocity exist underneath Africa and the Pacific. Their reduced velocity can be explained by an increased temperature or a different chemical composition. We use the gravity field to determine the density distribution inside the Earth's mantle and find that it favors a distinct chemical composition over a purely thermal cause.
At the bottom of the mantle (2850 km depth) two large volumes of reduced seismic velocity exist...
