Mapping And Analysis of Aerial Conductivity Measurements from INPUT System over Geothermal Areas

Remotely sensed electromagnetic data taken with an INPUT system for the U.S. Geological Survey in aerial surveys over a known geothermal resource area have been reduced and plotted in a gray scale format for two-and three-dimensional projections of the apparent subsurface conductance. The apparent conductance is calculated using both the channel ratio method and the theoretical two-layer model of the earth. Matching the survey data to the two-layer model gave good results consistent with the ratio method of apparent conductance calculation and permitted the construction of maps of horizontal slices of apparent conductance at different depths into the earth, from one to fifty meters. The channel ratio and horizontal slice maps of apparent conductance give a picture of the apparent conductance which is consistent with known topographical features of the regions.