Resistivity methods have been used for decades in geothermal explorations in 
Iceland. The most extensively used method is the TEM (Transient-ElectroMagnetic) 
method that has proven effective in delineating high temperature fields in the 
uppermost 1 km of the geothermal field.

The subsurface resistivity in high temperature geothermal fields in volcanic rock 
depends on mainly on temperature, the presence of conductive clay minerals, and the 
porosity. Fluid salinity is only important at high salinities.

Recent improvements in interpretation methods open up the possibility to look closer 
into the details of the temperature distribution and flow pattern within a 
geothermal system. Two new examples from geothermal fields in Iceland are presented. 
A TEM resistivity survey in the Reykjanes brine geothermal field shows an indication 
of two up-flow zones crossing at depth and lateral discharge zones at shallow 
depths. 

Results from Öxarfjörður, a geothermal field in sedimentary costal environments, 
show that up-flow zones are detected as well as lateral warm discharge zones and 
seawater flow along sedimentary layers.

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