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AGU: Geophysical Research Letters

 

Keywords

  • hydrothermal
  • resistivity
  • self-potential

Index Terms

  • Exploration Geophysics: Magnetic and electrical methods
  • Volcanology: Hydrothermal systems
  • Hydrology: Hydrogeophysics
  • Hydrology: Instruments and techniques: monitoring
  • Physical Properties of Rocks: Magnetic and electrical properties

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L12306, 5 PP., 2009
doi:10.1029/2009GL037573

A case study of resistivity and self-potential signatures of hydrothermal instabilities, Inferno Crater Lake, Waimangu, New Zealand

A. Legaz

LGIT, Université de Savoie, CNRS, Le Bourget-du-Lac, France

J. Vandemeulebrouck

LGIT, Université de Savoie, CNRS, Le Bourget-du-Lac, France

A. Revil

LGIT, Université de Savoie, CNRS, Le Bourget-du-Lac, France

Department of Geophysics, Colorado School of Mines, Golden, Colorado, USA

A. Kemna

Department of Geodynamics and Geophysics, University of Bonn, Bonn, Germany

A. W. Hurst

GNS Science, Lower Hutt, New Zealand

R. Reeves

GNS Science, Lower Hutt, New Zealand

R. Papasin

GNS Science, Lower Hutt, New Zealand

Inferno Crater Lake, Waimangu, one of the largest hot springs in New Zealand, displays vigorous cyclic behavior in lake level and temperature. It provides a natural small-scale laboratory for investigating the geo-electrical signature of fluid flows. We measured self-potential and electrical resistivity to see whether the huge variations of fluid volume, approximately 60,000 m3 during a mean cycle period of 40 days, could be detected. Electrical resistivity measurements revealed spectacular changes over time, with the medium becoming more conductive as the lake receded. This result is consistent with analog models, where the vapor phase is replaced by liquid at recession. The self-potential survey did not detect temporal changes related to fluid movements. This can be explained by the pH of the pore water (∼2.3), which is close to the point of zero charge of silica.

Received 23 February 2009; accepted 7 April 2009; published 18 June 2009.

Citation: Legaz, A., J. Vandemeulebrouck, A. Revil, A. Kemna, A. W. Hurst, R. Reeves, and R. Papasin (2009), A case study of resistivity and self-potential signatures of hydrothermal instabilities, Inferno Crater Lake, Waimangu, New Zealand, Geophys. Res. Lett., 36, L12306, doi:10.1029/2009GL037573.

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