Time Dependence of Magnetotelluric Fields in a Tectonically Active Region in Eastern Canada

  • R. D. Kurtz
  • E. R. Niblett
Conference paper
Part of the Advances in Earth and Planetary Sciences book series (AEPS, volume 5)


Magnetotelluric fields have been monitored for 3 years near the centre of seismicity in a tectonically active region on the north shore of the St. Lawrence River. The results indicate that electrical properties of upper crustal layers are strongly time-dependent in this area, and changes of more than 30% in the impedance tensor have been detected over a period of a few months. However, the most important part of the measured time dependence appears to be a trend increase in impedance of about 14% per year. There have been only two earthquakes greater than magnitude 3.0 in the area since recording began in 1974 and it has not been possible to develop a clear association between seismic activity and resistivity changes. Seasonal variations in the temperature and salinity of the nearby St. Lawrence River may be a contributing factor. Much less change in impedance was observed at similar MT recording stations located outside the zone of seismicity.


Apparent Resistivity Impedance Tensor Vertical Crustal Movement Measured Time Dependence Apparent Resistivity Curve 
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Copyright information

© Center for Academic Publications Japan 1979

Authors and Affiliations

  • R. D. Kurtz
    • 1
  • E. R. Niblett
    • 1
  1. 1.Department of Energy, Mines and ResourcesEarth Physics BranchOttawaCanada

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