As fresh water resources continue to decrease, prospecting for groundwater using geophysical techniques takes on added importance, especially in arid areas. Hydrogeological monitoring of the fresh water/salt water interface is essential for maintaining water quality standards. THOR Geophysical's hydrogeologists combine all relevant measurement methods and ensure a detailed interpretation with respect to the local geology. Seismics (with in situ data processing) have proven to be a very effective groundwater prospecting tool. When groundwater is associated with faults or fracture zones, electromagnetic techniques, such as VLF or the Slingram method, and magnetic measurements are used to map structural aquifers. Furthermore, electrical sounding methods are applied to determine groundwater quality as well as aquifer depth and thickness. Many years of experience, particularly in Africa and the Middle East, have given THOR Geophysical a strong foundation in high quality and cost effective groundwater prospecting