Abstract
Annual mean data from worldwide magnetic observatories show that there was a jerk1 (step-change in the second time derivative) in the geomagnetic field, which took place over an interval of <2 yr around 1970. If such a short-lived phenomenon originated in the Earth's core, and were still detectable after passing through the mantle to the surface, this would imply a much lower conductivity for the lower mantle than had been believed previously. Here we show by an objective test that most of the jerk has an internal origin.
Similar content being viewed by others
References
Schot, S. H. Am. J. Phys. 46, 1090–1094 (1978).
Runcorn, S. K. Trans. Am. geophys. Un. 36, 191–198 (1955).
Currie, R. G. J. geophys. Res. 72, 2623–2633 (1967).
Alldredge, L. R. J. geophys. Res. 82, 5427–5431 (1977).
Stacey, F. D., MacQueen, H. W., Smylie, D. E., Rochester, M. G. & Conley, D. Trans. Am. geophys. Un. 59, 1027 (1978).
Yukutake, T. J. Geomagn. Geoelect., Kyoto 25, 195–212 (1973).
Achache, J., Courtillot, V., Ducruix, J. & Le Mouël, J.-L. Phys. Earth planet. Inter. 23, 72–75 (1980).
Courtillot, V., Ducruix, J. & Le Mouël, J.-L. C.r. hebd. Séanc. Acad. Sci., Paris D 287, 1095–1098 (1978).
Mizuno, H. J. Geomagn. Geolect., Kyoto 32, 413–420 (1980).
Alldredge, L. R. C.r. hebd. Séanc. Acad. Sci., Paris B 289, 169–171 (1979).
Courtillot, V., Ducruix, J. & Le Mouël, J.-L. C.r. hebd. Sëanc. Acad. Sci., Paris B 289, 173–175 (1979).
Ducruix, J., Courtillot, V. & Le Mouël, J.-L. Geophys. J. R. astr. Soc. 61, 73–94 (1980).
Le Mouël, J.-L., Madden, T. R., Ducruix, J. & Courtillot, V. Nature 290, 763–765 (1981).
Chan, H. D., Ducruix, J. & Le Mouël, J.-L. C.r. hebd. Séanc. Acad. Sci. Paris B 293, 157–160 (1981).
Malin, S. R. C., Hodder, B. M. & Barraclough, D. R. Ebro Observatory 75th Anniversary Vol. (in the press).
Alldredge, L. R. J. geophys. Res. 80, 1571–1578 (1975).
Alldridge, L. R. J. Geomagn. Geolect., Kyoto 32, 421–425 (1980).
Gauss, C. F. Allgemeine Theorie des Erdmagnetismus (Leipzig, 1839).
Lewis, A. G. Geomagn. Bull. Inst. geol. Sci. 10, 1–296 (1981).
Goldie, A. H. R. & Joyce, J. W. (eds) Association of Terrestrial Magnetism and Electricity—Trans. Washington Meet., 550 (Neill, Edinburgh, 1940).
Lowes, F. J. J. geophys. Res. 71, 2179 (1966).
Chapman, S. & Bartels, J. Geomagnetism 639 (Clarendon, Oxford, 1940).
Banks, R. Geophys. J. R. astr. Soc. 17, 457–487 (1969).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Malin, S., Hodder, B. Was the 1970 geomagnetic jerk of internal or external origin?. Nature 296, 726–728 (1982). https://doi.org/10.1038/296726a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/296726a0
- Springer Nature Limited
This article is cited by
-
Recent progress in identification of the geomagnetic signature of 3D outer core flows
Acta Geodaetica et Geophysica (2020)
-
Investigation of the SA evolution by using the CHAOS-4 model over 1997–2013
Science China Earth Sciences (2016)
-
Local time features of geomagnetic jerks
Earth, Planets and Space (2014)
-
The time-varying geomagnetic field of Southern Africa
Earth, Planets and Space (2014)
-
On the characteristics of successive geomagnetic jerks
Earth, Planets and Space (2014)