Abstract
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.
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References
Barsukov, O.M., Variations of electric resistivity of mountain rocks connected with tectonic causes, Tectonophysics, 14, 273–277, 1972.
Brace, W.F. and A.S. Orange, Electrical resistivity changes in saturated rock under stress, Science, 153, 1525–1526, 1966.
Brace, W.F. and A.S. Orange, Electrical resistivity changes in saturated rocks during fracture and frictional sliding, J. Geophys. Res., 73, 1433–1445, 1968a.
Brace, W.F. and A.S. Orange, Further studies of the effects of pressure on electrical resistivity of rocks, J. Geophys. Res., 73, 5407–5420, 1968b.
Buchbinder, G. and C. Keith, Search for changes in velocity in the La Malbaie region of Quebec, EOS, Trans. Am. Geophys. Union, 58, 433, 1977 (Abstr.).
Dunbar, W.S. and G.D. Garland, Crustal loads and vertical movements near Lake St. John, Quebec, Can. J. Earth Sci., 12, 711–720, 1975.
Fowler, R.A., B.J. Kotick, and R.D. Elliott, Polarization analysis of natural and artificially induced geomagnetic micropulsations, J. Geophys. Res., 72, 2871–2883, 1967.
Frost, N.H. and J.E. Lilly, Crustal movement in the Lake St. John area, Quebec, Can. Surv., 20, 292–299, 1966.
Honkura, Y., R.D. Kurtz, and E.R. Niblett, Geomagnetic depth sounding and magnetotelluric results from a seismically active region northeast of Quebec City, Can. J. Earth Sci., 14, 256–267, 1977.
Honkura, Y., E.R. Niblett, and R.D. Kurtz, Changes in magnetic and telluric fields in a seismically active region of eastern Canada: Preliminary results of earthquake prediction studies, Tectonophysics, 34, 219–230, 1976.
Kumarapeli, P.S. and V.A. Savll, The St. Lawrence Valley System: A North American equivalent of the East African Rift Valley System, Can. J. Earth Sci., 3, 639–658, 1966.
Kurtz, R.D. and G.D. Garland, Magnetotelluric measurments in eastern Canada, Geophys. J. R. Astr. Soc, 45, 321–347, 1976.
Lambert, A., J. Liard, and H. Dragert, Canadian precise gravity networks for crustal movement studies; an instrument evaluation, Tectonophysics, 52, 87–96, 1979.
Leblanc, G. and G.G.R. Buchbinder, Second microearthquake survey of the St. Lawrence Valley near La Malbaie, Quebec, Can. J. Earth Sci., 14, 2778–2789, 1977.
Leblanc, G., A.E. Stevens, R.J. Wetmiller, and R. Du Berger, A micro-earthquake study of the St. Lawrence Valley near La Malbaie, Quebec, Can. J. Earth Sci., 10, 42–53, 1973.
Mazzella, A. and H.F. Morrison, Electrical resistivity variations associated with earthquakes on the San Andreas Fault, Science, 185, 855–857, 1974.
Reddy, I.K., R.J. Phillips, J.H. Whitcomb, D.M. Cole, and R.A. Taylor, Monitoring of time dependent electrical resistivity by magnetotellurics, J. Geomag. Geoelectr., 28, 165–178, 1976.
Robertson, P.B., La Malbaie structure, Quebec—A Palaeozoic meteorite impact site, Meteoritics, 4, 1–24, 1968.
Robertson, P.B., Zones of shock metamorphism at the Charlevoix impact structure, Quebec, Bull. Geol. Soc. A, 86, 1630–1638, 1975.
Rondot, J., Nouvel impact meteoritique fossile? La structure semicirculaire de Charlevoix. Can. J. Earth Sci., 5, 1305–1317, 1968.
Sims, W.E., F.X. Bostick, and H.W. Smith, The estimation of magnetotelluric impedance tensor elements from measured data, Geophysics, 36, 938–942, 1971.
Smith, W.E.T., Earthquakes of eastern Canada and adjacent areas 1534–1927, Publ. Dom. Obs..Ottawa, 26, 271–301, 1962.
Smith, W.E.T., Earthquakes of eastern Canada and adjacent areas 1928–1959, Publ. Dom. Obs., Ottawa, 32, 87–121, 1966.
Trigg, D.G., An amplifier and filter system for telluric signals, Publ. Earth Phys. Branch, Ottawa, 44, 1–5, 1972.
Trigg, D.G., P.H. Serson, and P.A. Camfield, A solid state electrical recording magnetometer. Publ Earth Phys. Branch, Ottawa, 41, 67–80, 1970.
Vanicek, P. and A.C. Hamilton, Further analysis of vertical crustal movement observations in the Lac St. Jean area, Quebec, Can. J. Earth Sci., 9, 1139–1147, 1972.
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Kurtz, R.D., Niblett, E.R. (1979). Time Dependence of Magnetotelluric Fields in a Tectonically Active Region in Eastern Canada. In: Fuller, M., Johnston, M.J.S., Yukutake, T. (eds) Tectonomagnetics and Local Geomagnetic Field Variations. Advances in Earth and Planetary Sciences, vol 5. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-9825-0_11
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DOI: https://doi.org/10.1007/978-94-010-9825-0_11
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