2D and 3D Modeling of Magnetotelluric Data for Geothermal Exploration : Cases Study at the Taupo Volcanic Zone, New Zealand
Speaker: Irwan
Abstract
The geothermal fields in the Taupo Volcanic Zone (TVZ), in the central North Island of New Zealand was provide ~10% of New Zealand's electricity demand, but development is currently limited to depths of 2-3 km. To increase this level of geothermal energy in the long term, exploration from depths > 3 km will be required . Previously, regional MT (magnetotelluric) surveys of the central TVZ have imaged the crustal resistivity structure to depths of 30-40 km. In addition, closed-spaced MT and seismic surveys have been conducted locally at individual geothermal fields to investigates shallow structures (upper 3 km). These paper focus on detailed basement structure in the upper 10 km using dense array of MT measurements. Using Phoenix MTU instruments, broadband MT data were recorded that form a array of measurements at the south-eastern margin of the TVZ. These array data are used to investigate mechanisms by which the TVZ's extraordinarily high heat heat flux is transported to the surface. Taken together with seismological data, these MT data show compelling evidence that support a model of hydrothermal convection within the brittle (upper ~6-7 km) part of the crust. Both 2D and 3D models of these MT data show vertical low resistivity zones that connect surface geothermal fields to an inferred magmatic heat source that lies below the brittle-ductile transition.
Reference
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