New Zealand Journal of Geology and Geophysics abstracts

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Short communication 

Temporally linked volcanic centres in the Auckland Volcanic Field

John Cassidy
Corinne A. Locke

Department of Geology
University of Auckland
Private Bag 92 019
Auckland, New Zealand

Abstract  New aeromagnetic data from the Auckland Volcanic Field reveal negative magnetic anomalies over Taylor Hill and Mt St John volcanoes which are interpreted as resulting from anomalous remanent magnetisation directions. These anomalies are comparable in character to those occurring over three volcanoes in the southern part of the field that record coincident anomalous directions associated with a geomagnetic excursion. Since rates of change of the geomagnetic field may be rapid during such excursions, and their duration short, a strong temporal link is implied between these five separate volcanic centres, which are geographically spread throughout the Auckland field. Even assuming normal rates of secular variation, the total time period for these eruptions might be only several hundred years, which suggests a recurrence interval for these volcanoes that is much less than any currently estimated for the field.

Keywords  Auckland Volcanic Field; aeromagnetic anomalies; geomagnetic excursion; Taylor Hill; Mt St John; volcanic hazard

G03028; Received 26 August 2003; accepted 15 December 2003; Online publication date 20 May 2004
New Zealand Journal of Geology & Geophysics, 2004, Vol. 47: 287–290
0028–8306/04/4702–0287 © The Royal Society of New Zealand 2004

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