A geophysical survey uses various technologies like seismic, magnetic, or electrical methods to study the physical properties of the subsurface. These surveys are essential for locating water sources, minerals, and other underground resources, as well as for site planning and environmental assessments. 

EIA is a critical process that evaluates the potential environmental effects of a proposed project or development. It ensures that the environmental consequences are considered and addressed before any activity, such as drilling or construction, begins.