Temporally linked volcanic centres in the Auckland Volcanic Field

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.