Origin of Magnetic Anomalies Over the Central Volcanic Region of New Zealand

  1. Leon Knopoff,
  2. Charles L. Drake and
  3. Pembroke J. Hart
  1. Alexander Malahof

Published Online: 18 MAR 2013

DOI: 10.1029/GM012p0218

The Crust and Upper Mantle of the Pacific Area

The Crust and Upper Mantle of the Pacific Area

How to Cite

Malahof, A. (2013) Origin of Magnetic Anomalies Over the Central Volcanic Region of New Zealand, in The Crust and Upper Mantle of the Pacific Area (eds L. Knopoff, C. L. Drake and P. J. Hart), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM012p0218

Author Information

  1. Hawaii Institute of Geophysics, University of Hawaii, Honolulu, Hawaii

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 20 APR 2012

Book Series:

  1. Geophysical Monograph Series

Book Series Editors:

  1. Waldo E. Smith

ISBN Information

Print ISBN: 9780875900124

Online ISBN: 9781118663738

SEARCH

Keywords:

  • Amplitude and coromandel volcanics;
  • Magnetic anomalies and Mamaku plateau;
  • Maroa volcanic center;
  • Residual total force magnetic anomalms;
  • Rotorua caldera;
  • Tongariro National Park and Rangitaiki ignimbrites;
  • Volcanic cones and domes;
  • Wairakei geothermal field and Lake Taupo pumice vents

Summary

Structural analyses of the residual total force magnetic anomalies over the central volcanic region of the North Island of New Zealand show that the anomalies are related to centers of volcanism and cannot be due to topographic effects alone. Two prominent alignments are evident in the anomalies: one of these parallels the strike of the Coromandel volcanics of the North Island and the strike of the Norfolk ridge, the other parallels the axis of the Taupo-White Island graben and the strike of the Tonga-Kermadec ridge and the Tonga-Kermadec trench. None of the anomalies associated with the large crustal fissures indicates a connection between the centers of volcanism within the region. Each major volcanic center can be related to local regions of magnetic highs. The amplitude of the individual anomalies decreases with increasing distance away from the principal volcanic centers. Amplitudes only rarely reach hundreds of gammas, and anomaly wavelengths are similar to the wavelengths of anomalies observed over the Hawaiian volcanoes and volcanoes of the Kamchatka Peninsula. Structural interpretations of the anomalies suggest that the volcanoes of the New Zealand central volcanic region are similar to other volcanoes of the Pacific rim, such as those of the Kamchatka Peninsula, but differ from volcanoes inside the Pacific basin, such as those of the Hawaiian Islands. The greater proportion of magnetic anomalies associated with volcanic centers appears to result from normally polarized magnetic bodies.