Soil radon survey for tracing active fault: a case study along Qena-Safaga road, Eastern Desert, Egypt

High concentrations of radon are often used as a geophysical tool for uranium exploration, earthquake and volcanic activity predication, and fault zones confirmation. The aim of this study was to assure the suitability of this method in the study of fault zones. For this purpose, a portable AlphaGUARD PQ 2000 device was used to detect the fracture zones along Qena-Safaga road, Eastern Desert, Egypt. Radon soil gas anomalies were found to be linearly distributed along NW-SE and NE-SW trends. Such directions agree well with the directions of the active fault deduced from earlier studies. Radon concentration in soil along the repeated three profiles was anomalously high in all fault zones by a factor of 3-6 above background values. In the profiles studied, the peaks recorded on the fault trace were found to be higher than the background. The analysis of the water samples collected from a well in the studied area showed that the HCO3 contents exceeded 1000 ppm, providing an additional evidence that the area under study is likely to be included within a major seismic belt. This study confirms strongly that radon gas and hydrochemical studies are a good tool for fault zones detection in similar areas. (C) 2003 Elsevier Science Ltd. All rights reserved.