J. Ole Kaven Nicholas C. Davatzes Gregory A. Newman Nathaniel J. Lindsey 2017 <p><span>Previous magnetotelluric (MT) studies of the high-temperature Coso geothermal system in California identified a subvertical feature of low resistivity (2–5&nbsp;Ohm m) and appreciable lateral extent (&gt;1&nbsp;km) in the producing zone of the East Flank field. However, these models could not reproduce gross 3-D effects in the recorded data. We perform 3-D full-tensor inversion and retrieve a resistivity model that out-performs previous 2-D and 3-D off-diagonal models in terms of its fit to the complete 3-D MT data set as well as the degree of modelling bias. Inclusion of secondary&nbsp;</span><i>Z</i>_<i>xx</i><span><span>&nbsp;</span>and<span>&nbsp;</span></span><i>Z</i>_<i>yy</i><span><span>&nbsp;</span>data components leads to a robust east-dip (60†) to the previously identified conductive East Flank reservoir feature, which correlates strongly with recently mapped surface faults, downhole well temperatures, 3-D seismic reflection data, and local microseismicity. We perform synthetic forward modelling to test the best-fit dip of this conductor using the response at a nearby MT station. We interpret the dipping conductor as a fractured and fluidized compartment, which is structurally controlled by an unmapped blind East Flank fault zone.</span></p> application/pdf 10.1093/gji/ggw408 en Oxford Academic Compartmentalization of the Coso East Flank geothermal field imaged by 3-D full-tensor MT inversion article