For earth scientists, a wide range of geophysical surveying methods exist for geothermal energy investigations. For geophysics, location of a geothermal reservoir may be determined by use of seismic velocity, electrical conductivity, magnetic or/and gravity methods. Effects of exploitation of a geothermal reservoir can be monitored using micro-seismic, micro-gravity, geo-chemical and temperature/pressure techniques. Though these may require complex methodology and relatively advanced mathematical treatment in interpretation, much information may be derived from simple qualitative assessment of the survey or monitoring data. Many of these methods are often used in combination to obtain a plausible inference. At the interpretation stage, ambiguity arising from the results of one survey may often be removed by the consideration of results from a second survey method.