Iraqi National Journal of Earth Science

Abstract

The present study involves applying a new system by picking the apparent resistivity values ​​ from the pseudo-tomography at seven depth's levels and nine orientations with an angle of 20 ° around the mid central point of a 200 m array lengths. The system, which is called the Azimuth Mutib and Al-Fadhel System (AMAS), consists of three types of the electrode arrangement patterns, the first is the Azimuthal Radial Resistance Technique (ARRT) for measurements of resistivity (ρ_D1 & ρ_D2), the second is the Azimuthal Forward Resistance Technique (AFRT) for measurements of resistivity (ρ_D0 & ρ_D2), and the third is the Backward Resistance Technique (ABRT) for measurements of resistivity (ρ_D0 & ρ_D1).
A new mechanism is used in this study that includes a series of calibration steps of the electrode spacing intervals with the apparent depth’s levels and median of the depth of investigation, due to the inability of picking the resistivity values of the true depth's levels from electrical resistivity imaging because there is a wide spectral gradient range of colors. As well, the absence of correlating the values ​​of the depth's levels with the electrode spacing in the RES2DINV software. Accordingly, three values were determined for the missing apparent depth's levels with confirmation of the accordant values of the eight levels of the tomography.
The data of the ART are represented using radial, forward and backward techniques at four sites using polar graphs and Cartesian curves. According to the mechanisms used in global and local studies and researches, the results are analyzed and for determining the values ​​and trends of the electrical anisotropy for Quaternary deposits and the upperlayers of Fatha Formation in the present study area.
The study displays a notable success in applying AMAS by matching between its three mechanisms and deduced the presence of six directions for the strikes of tension and shear fractures (primary and secondary) at two sites near the Mosul Dam penetrating fluvial and alluvial deposits of the Quaternary age.