Delineation of Subsurface Fractures Density Within and Out of Abu-Jir Fault Zone Using 2D Imaging Resistivity Technique echniqueechnique , A case Study from Southwest of Karbala City, Central Iraq

Abstract

The 2D imaging survey was carried out using Wenner-Schlumberger array through (11) 2D survey lines distributed within and out of Abu-Jir fault zone, Southwest of Karbala City, central Iraq. The aim is to delineate subsurface fractures density. The total length of each 2D survey line is (600m.) with the unit electrode spacing (a) equals to (10m.).The results showed two types of fractures zones. The first type is formed by dissolution process of carbonate rocks, while the second fractures zone is formed from tectonic movements, and it includes two types of fractures system, oblique and vertical fractures.
This study includes comparison between subsurface fracture density within and out of Abu- Jir fault zone. This comparison showed that the fracture zones are characterized by increasing of resistivity values within Abu- Jir fault zone to reach (106.1 Ω.m), while it decreases out of this zone to reach (30.9 Ω.m). This is caused by increasing groundwater salinity out of this zone. In addition, the fractures density within Abu- Jir fault zone is more than outer ones, despite they have high resistivity values. In general, they increase with the depth, in (NE) direction within and out of this zone. The results indicated that the best area of groundwater investment is located within Abu- Jir fault zone