Team back on 'emotional' search for lost terraces

Cornel de Ronde wants to send a remote-controlled vehicle into Lake Rotomahana to film what's left of the terraces. Photo / Alan Gibson

A team of scientists has resumed an "emotional" mission to digitally resurrect New Zealand's long-lost eighth natural wonder of the world - the famous Pink and White Terraces.

By the end of the week, the team from GNS Science, Niwa and the University of Waikato hopes to have created a detailed map of the terraces and their surrounding landscape, which for 125 years have been hidden beneath Lake Rotomahana south of Rotorua.

Until a breakthrough discovery last year, it was thought the terraces had been destroyed in the devastating 1886 Mt Tarawera eruption.

Project leader Cornel de Ronde, of GNS Science, said he was confident the survey would provide further evidence parts of the pink terraces had survived.

He was less certain about the white terraces, which were in an area that seemed more affected by the eruption.

"Where the white terraces are, the landscape looks different... But where the pinks are, they may have been shielded by much of the blast and... preserved by the mud," he said.

Mr de Ronde has been fascinated by the terraces all his life - his great- great-grandmother also once painted the landmark - and he could name few projects more exciting.

"Bringing back the eighth wonder of the world to people, you can't get more exciting than this.

"Supposedly it was all gone and done and dusted - maybe much of it is - but the point is there are still some vestiges there."

The team's work would also digitally uncover the landscape surrounding the terraces as it was on June 10, 1886, before the lake was formed. "It's important for people to try to understand how that eruption really occurred, because there were some devastating consequences."

Features found in a rift filled by sediment over 125 years included several craters and what could be the bottom tier of the terraces on its margin.

Once a 3D map was complete, the next possibility was sending a remote-controlled vehicle into the lake to gather high-definition video images.

The buzz around the discovery was also expected to be a boon for local tourism. "I've had people write and tell me how joyful they felt when the news came out."

The project

Scientists hope to map the Pink and White Terraces site.

Boat-towed seismic equipment capable of mapping geological structures to a depth of 70m is being used to gain a clearer picture of the geothermal wonders below Lake Rotomahana.

The equipment releases acoustic vibrations that penetrate the lake floor and bounce off geological layers. Data is recorded on underwater microphones attached to the boat.

This enables scientists to see through thick layers of mud and sediment and create images of faultlines and rift zones that define the 1886 eruption and, possibly, the upflow channels of the lake's geothermal systems.

The data will be used to make charts showing cross-sections through the upper parts of the earth's surface below the lake floor.

Scientists are keen to learn how the geothermal systems survived during the Mt Tarawera eruption, and how they have adapted at the bottom of a lake.

The seismic images should provide a clearer picture of the remnants of the Pink and White Terraces discovered last year by free-swimming robotic vehicles with sonar.