Scientists deploy one of the survey instruments in Lake Okataina. Photo / Supplied
Scientists deploy one of the survey instruments in Lake Okataina. Photo / Supplied
A survey of lakes in the Rotorua region will help scientists build a more complete picture of geothermal resources and volcanic hazards under the Bay of Plenty.
The electromagnetic survey involves a technique called magnetotellurics, or MT, which helps scientists identify where geothermal fluids may be present deep within the earth.
It's the first time this technique, which measures low-frequency electromagnetic waves in the Earth's crust, has been used in New Zealand lakes.
The survey is a joint project involving GNS Science and Bay of Plenty Regional Council and will collect data at Lakes Rotorua, Tarawera, Okataina, and Rotoiti.
The researchers will also take their equipment to Mokoia Island to give more complete coverage of Lake Rotorua.
The project has the support of Te Arawa Lakes Trust and Mokoia Island Trust.
Project leader, Ted Bertrand of GNS Science, said: "We have taken hundreds of measurements on land using this technique, but at present, we have holes in our data where the lakes are."
Dr Bertrand presenting research to Rotorua residents in February. Photo / File
Bay of Plenty Regional Council's geothermal programme leader Penny Doorman said as managers of the resource, it was important that this type of work was undertaken.
"For the regional council, our aim is to increase our understanding of the wider geothermal resource and volcanic hazard in the region surrounding Rotorua."
The measurements will be taken by lowering specialist instruments to the lakebed of each lake and leaving them in place for two days to collect data.
Initial results are expected at the end of this year.
Following the project, a hui will be arranged in Rotorua where scientists will share preliminary findings with Te Arawa and the wider community.
The findings will complement existing data which has already been used for the sustainable management of geothermal fields, for exploration of new deep geothermal resources, and for management of volcanic hazards.
In February, Dr Bertrand presented this earlier research done on land, to 180 to 200 community members in Rotorua, including iwi members, councillors, residents, and fellow scientists.
Dr Bertrand said there could be a large, untapped geothermal resource between Rotorua and Taupō.
He was among a team of three scientists and at least four technicians who had modelled rock types, depths, and temperatures in 366 sites across the Rotorua and Okataina calderas, since 2015, building on previous research started near Taupō in 2009.
Geothermal energy accounts for 18 per cent of New Zealand's electricity generation.
Taupō Volcanic Zone facts - Rotokawa hosts the world's largest single geothermal turbine - The Taupō caldera had the world's last super-eruption more than 26,500 years ago when 1000cu km of material was emptied - In comparison, the Okataina caldera has erupted 80cu km of material in the last 21,000 years, including the 1886 eruption of Mt Tarawera
