INTERPRETATION OF VLF MEASUREMENTS RELATED TO HYDROGEOLOGICAL SURVEYS


Published: Jan 1, 2007
Keywords:
VLF hydrogeology
G. Vargemezis
Abstract

The aim of the application of VLF surveys in hydrogeology is the contribution to the decision making as concern the construction of a well. Geophysical survey by the application of VLF method must respond to the questions (a) if the construction of a well should be proposed or not, and if the answer is yes then (b) where exactly must be located. These answers are very crucial ones, since VLF methods is applied mainly in areas where bedrock is close to the surface and no chance has a well if it will not drill an aquiferous fault. Problems arise by the fact that the target to be detected is a conductive body which is interpreted as a fault filled with water. The major question that is posed to the surveyor is if the conductivity of the fault is caused by fresh water or by clay materials or saline water. Forward models of different resistivity contrast between host rock and conductive body have been computed and examined. Results show that interpretation of the imaginary part is very important to the evaluation of the data. Since the conductor -in the meaning of water presence onlymust be a medium one, a high value of the real part should be expected in parallel with a close to 0 value of the imaginary component which also must show one peak to the Fraser filtered data.

Article Details
  • Section
  • Hydrology and Hydrogeology
Downloads
Download data is not yet available.
References
Archie, G., 1942. AIME Trans. 146, 54
Benson, Α., Payne, K., and Stubben, M., 1997. Mapping groundwater contamination using ds resistivity and VLF geophysical methods - a case study, Geophysics, 62(1), 80-86.
Drahor, M., and Berge, M., 2006. Geophysical investigations of the Seferihisar geothermal area, Western Anatolia, Turkey, Geothermics, 35, 302-320.
Fraser, D.C., 1969. Contouring of VLF-Em data, Geophysics, 34(6), 958-967.
Gharibi, M., and Pedersen, L., 1999. Transformation of VLF data into apparent resistivities and phases, Geophysics, 64(5), 1393-1402.
Hautot, S., Tarits, P., Perrier, F., Tarits, C, and Trique, M., Groundwater electromagnetic imaging in complex geological and topographical regions: A case study of a tectonic boundary in the French Alps, Geophysics, 67(4), 1048-1060.
Hutchinson, P., and Barta, L., 2002. VLF surveying to delineate longwall mine-induced fractures, The Leading Edge, 493.
Raikkonen, P., and Sharma, S.P., 1998. 2-D non linear inversion of VLF and VLF-R data using simulated annealing, Journal of Applied Geophysics, 39, 155-176.
Karous, M., and Hjelt, S.E., 1983. Linear filtering of VLF dip-angle measurements, Geophys. Prosp., 31, 782-794.
Keller, E.A., 1996. Environmental Geology 7th edn (Englewood Cliffs, N. J: Prentice-Hall). McNeill, J.D., and Labson, V.F., 1990. Geological mapping using VLF radio fields. In M. Nabighian (ed.), Electromagnetic Methods in Applied Geophysics, Volume 2, Part B: Tulsa, Oklahoma, Society of Exploration Geophysicists, 521-640pp.
Monteiro Santos, F., Almeida, E., Gomes, M., and Pina, Α., 2006. Hydrogeological investigation in Santiago island (Cabo Verde) using magnetotellurics and VLF methods, Journal of African Earth Sciences, 421 -430.
Monteiro Santos, F., Mateus, Α., Figueiras, J., and Goncalves, M., 2006. Mapping groundwater contamination around a landfill facility using the VLF-EM method - A case study, Journal of Appllied Geophysics 60, 115-125.
Nissen, J., 1986. Versatile programs for geoelectromagnetic interpretation, Doctoral Thesis, Lulea Tekniska Universitet.
Parasnis, D.S, 1995. Principles of Applied Geophysics, Chapman et Hall Ed., Fifth Edition, 429pp.
Sampaio, E., and Dias, C, 2001. Electromagnetic profiling interpretation across vertical faults and dikes, Geophysical Prospecting, 49, 107-119.
Saydam, Α., 1981. Very low-frequency electromagnetic interpretation using tilt angle and ellipticity measurements, Geophysics, 46(11), 1594-1605.
Sharma, S.P., and Baranwal, V.C., 2005. Delineation of groundwater-bearing fracture zones in a hard rock area integrating very low frequency electromagnetic and resistivity data, Journal of Applied Geophysics, 57, 155-166.
Zlotnicki, J., Vargemezis, G., Mille, Α., Bruere, F., and Hammouya, G., 2006. State of the hydrothermal activity of Soufrière of Guadeloupe volcano inferred by VLF surveys, Journal of Applied Geophysics, 58, 265-279.
Most read articles by the same author(s)