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| Titel |
Effect of mantle electrical conductivity on the geomagnetic secular variation |
| VerfasserIn |
K. Pinheiro, A. Jackson, J. Velímský |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250019318
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| Zusammenfassung |
| The electrical conductivity of the Earth’s mantle has been a subject of much debate in the last
few years. Induction studies agree mainly in the first 1000 km of the mantle, however in the
lower mantle the conductivity is still very uncertain. Experimental studies of mineral
physics simulating the conditions of the deep mantle have been performed and
results disagree by 3 orders of magnitude depending, for example, on the considered
geotherm, composition, etc. As a complement to mineralogical and induction studies,
geomagnetic jerks can also contribute towards a better understanding of mantle
conductivity.
Geomagnetic jerks involve abrupt temporal changes in the secular variation of Earth’s
magnetic field and are believed to be due to motions in the fluid core. The secular variation
around the time of a jerk was modeled by two straight-line segments, where their intersection
defines the jerk occurrence time and the difference between the two slopes defines the jerk
amplitude. We detected global jerks occurring at 1969, 1978, and 1991 that show different
time arrivals at the surface, with differential time delays of the order of 2 years. One
way to explain this intriguing temporal pattern is to consider the Earth’s mantle
as a conductor, consequently the secular variation observed at the Earth’s surface
will correspond to a filtered version of the original time variations generated in the
core.
In this work, we used Vel |
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