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Building a better picture of underground heat

GNS Science has perfected a geophysical technique that helps scientists and others gain a better understanding of deep geothermal resources and volcanic hazards in the Taupō Volcanic Zone.

Scientists taking measurements from a boat. Photo: Brad Scott

Magnetotellurics help scientists build a picture of geothermal fields. Photo: Brad Scott


“As managers of the geothermal resource, it is important that this type of work was undertaken. For the Regional Council, these data will contribute to our understanding of the wider geothermal resource and volcanic hazard in the region surrounding Rotorua.”

Penny Doorman, Bay of Plenty Regional
Council, Geothermal Programme Leader


Called magnetotellurics, it maps electrical conductivity of rocks to a depth of 10km or more below the ground. This enables scientists to build a picture of geothermal fluids and magma bodies deep below the surface, and to see the connections between the shallow parts of geothermal fields and the underlying magmatic systems that provide the heat. 

Our team has developed an international reputation in the use of this technique. Since 2009 they have collected this electromagnetic data at more than 1000 locations in the central North Island. 

This year they partnered with Bay of Plenty Regional Council, Te Arawa Lakes Trust and Scripps Institute of Oceanography to collect this geophysical data from four lakes in the Rotorua region — Tarawera, Okataina, Rotoiti and Rotorua. This represents the first ever MT data measured in lakes in New Zealand. 

Results will be useful to Māori landowners, regional councils, geothermal companies and scientists studying volcanic hazards.