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The probability of a future geomagnetic reversal: Insight from new archeomagnetic studies in southern Africa

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Monday, September 28, 2009, 4 pm

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John Tarduno
University of Rochester
Rochester, NY

The dramatic decay of Earth's dipole magnetic field observed over the last 150 years has led to speculation that we are heading toward a geomagnetic field reversal. The unusual nature of the decay is highlighted by its rapid time-scale, as compared to ohmic resistance, and models predicting constant field intensities between 1590 and onset of the decay near 1840. These and some models which call for only minor fluctuations of field strength for Southern Hemisphere (SH) sites extending to more than a thousand years before present are limited by the lack of SH archeomagnetic values. I will discuss new archeomagnetic results from ceramics of southern Africa resulting from collaborations between the Paleomagnetic Research Group at the University of Rochester and colleagues at KwaZulu-Natal University and Witwatersrand University in South Africa. These yield field strength values that match model predictions for the 1700-1800 interval but also reveal centennial scale variations for older times that are not captured in prior models. I will discuss the implications of these results for the geodynamo and future of the field, as well as efforts to better define the past variations using multiple types of archeomagnetic objects (e.g. ceramics and burnt structures) and different paleointensity techniques.

Host Aleksey Smirnov (


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