The Circular Vertical Sounding Method Applied to the Exploration of the Dhamar-Rada'a (Y.A.R.) Geothermal Area

Abstract

We illustrate the use of a new geophysical prospecting method in the detailed investigations of a geothermal field. The method, called "Circular Vertical Soundings" (CVS) is useful in determining the predominant orientation of deep fracturing of rocks and their schistosity. In geothermal studies it is particularly useful to know the direction or directions of the predominant basement fracture systems since these could be the conduits responsible for the flow of hot fluids. The method is based on the Quardripole Schlumberger Technique, and in practice one carries out 4 to 6 vertical electrical soundings (VES) with the same center but different azimuth thereby permitting one to measure the relationship between apparent resistivity and azimuth; results are plotted on polar diagrams. The validity of the method is demonstrated through its application to the Dhamar-Rada's (YAR) geothermal area, where four CVS were carried out together with 83 conventional VES.