Localisation and direction determination of fissures with geoelectric methods in narrow, elongated measuring areas

S. Szalai, M. Abd Alla, S. Ahmed, L. Szarka

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In this paper we provide a field example for the determination of the location and direction of fissures in narrow, elongated measuring areas. The test measurements were carried out on the Mokattam plateau at Cairo (Egypt). Direction, length of the layout and the profile length all were very limited, since the measurements had to be carried out within a narrow (2-10 m wide) stripe, between a built-in area and a cleft rim. Interpretation of field measurements was supported by (1) analogue model experiments, and (2) parameter sensitivity maps. As it was found from laboratory experiments, fissures are indicated by potential- difference maximums along profiles measured by using three-electrode array (if the reference point is between the potential electrodes). The mean distance between two neighbouring maximums throughout the whole profile was found to be about 3-4 m, corresponding to the distance between the most visible fissures on the cleft wall. The Schlumberger null-array has been found to be an appropriate tool in determination of the direction of fissures. Its resolution is higher than that of the classical Schlumberger array. Its only disadvantage is that on the azimutal diagram it gives two times more minimum pairs than the number of fissures. Among such constrained circumstances the best method to get useful information about location and direction of fissures in the subsurface limestone is to use jointly corresponding traditional and null-arrays. While the location is given best by traditional three-electrode array measurement, the direction of the fissures is given from the joint interpretation of the Schlumberger null-array and the traditional Schlumberger array. In this way it is to separate several fissure directions.

Original languageEnglish
Pages (from-to)285-296
Number of pages12
JournalActa Geodaetica et Geophysica Hungarica
Volume36
Issue number3
DOIs
Publication statusPublished - Dec 1 2001

Keywords

  • Analogue modelling
  • Fissure direction
  • Geoelectrical null-arrays
  • Parametersensitivity map

ASJC Scopus subject areas

  • Building and Construction
  • Geophysics
  • Geology

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