Model of the geoelectrical structure of the mid- and lower mantle in the Europe–Asia region

The conductivity structure of the Earth’s mantle was estimated using the induction method down to 2100km depth for the Europe–Asia region. For this purpose, the responses obtained at seven geomagnetic observatories (IRT, KIV, MOS, NVS, HLP, WIT and NGK) were analysed, together with reliable publishe...

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Bibliographic Details
Published in:Geophysical journal international 1999-08, Vol.138 (2), p.549-552
Main Authors: Semenov, V. Yu, Jozwiak, W.
Format: Article
Language:English
Subjects:
electrical conductivity
electromagnetic induction
lower mantle
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Summary:The conductivity structure of the Earth’s mantle was estimated using the induction method down to 2100km depth for the Europe–Asia region. For this purpose, the responses obtained at seven geomagnetic observatories (IRT, KIV, MOS, NVS, HLP, WIT and NGK) were analysed, together with reliable published results for 11yr variations. 1-D spherical modelling has shown that, beneath the mid-mantle conductive layer (600–800km), the conductivity increases slowly from about 1Sm−1 at 1000km depth to 10Sm−1 at 1900km, while further down (1900–2100km) this increase is faster. Published models of the lower mantle conductivity obtained using the secular, 30–60yr variations were also considered, in order to estimate the conductivity at depths down to the core. The new regional model of the lower mantle conductivity does not contradict most modern geoelectrical sounding results. This model supports the idea that the mantle base, situated below 2100km depth, has a very high conductivity.
ISSN:0956-540X
1365-246X
DOI:10.1046/j.1365-246X.1999.00888.x