TEM and MT resistivity surveying : data acquisition, processing and 1D inversion with an example from Hágöngur geothermal field, Mid-Iceland

Abstract

Geophysical methods are some of the most effective geothermal exploration methods. Some of them are aimed at parameters that are directly influenced by the geothermal activity, such as resistivity and thermal methods, while others are aimed at geological parameters, and thus referred to as indirect methods. Electrical resistivity methods like magnetotellurics (MT) and transient electromagnetics (TEM) are most successful in identifying geothermal resources. This report discusses these two methods and describes the data acquisition, processing and 1D inversion using a practical example from MT and TEM surveys that were carried out in the Hágöngur area, Mid-Iceland by Iceland GeoSurvey (ÍSOR), in 2011 and 2013. The data were processed and inverted one-dimensionally (1D) using different software like: SSMT2000, MTEditor, TEMX and TEMTD. The results of the 1D joint inversion are presented as resistivity cross-sections and iso-resistivity maps down to different depths. Finally, the geothermal significance of the resistivity model is discussed.