Summit County Citizens Voice

A painting of the Pink Terraces prior to 1886. (Painting courtesy Alexander Turnbull Library)

Underwater researchers say they’ve found the buried remnants of the once-famed pink and white terraces of Lake Rotomahana

By Summit Voice

SUMMIT COUNTY — A team of researchers from New Zealand and the U.S. say they’ve discovered the submerged remains Lake Rotomahana’s long-lost Pink Terraces, once acclaimed as a world wonder.

Sightseers from around the world once traveled to the North Island to view the natural formations created by a large geothermal system, but the 1886 eruption of Mt. Tarawera buried the formation in sediments and enlarged the lake, engulfing the terraces. For more than a century, people have speculated whether any part of the Pink and White Terraces survived the eruption.

But last week, scientists from New Zealand’s GNS Science, one of several government laboratories, in collaboration with engineers and scientists from Woods Hole Oceanographic Institution and colleagues from Lamont-Doherty Earth Observatory of Columbia University and NOAA-PMEL, located portions of the long-lost Pink Terraces.

The research team used autonomous underwater vehicles to map the bottom of Lake Rotomahana. They said they are certain they have found the lower portions of the Pink Terraces on the lake floor. Project leader Cornel de Ronde, of GNS Science, said the team was elated by the discovery.

“The first sidescan sonar image gave a hint of a terraced structure so we scanned the area twice more and we are now 95 percent certain we are seeing the bottom two tiers of the Pink Terraces,” de Ronde said.

Side-scan sonar and bathymetric data collected by two REMUS 100 AUVs clearly show crescent-shaped terraced structures in about 60 meters of water where the Pink Terraces were located prior to 1886. They are covered by a brownish lake sediment.

Dr. de Ronde said the rest of the Pink Terraces were either destroyed during the eruption, or are still concealed under thick sediment not able to be penetrated by high-frequency AUV sonars.
The scientists found no sign of the larger White Terraces in the part of the lake that matched their location prior to 1886. The two terraces, part of a very large on-land geothermal system, were separated by several hundred meters prior to the eruption.

There are very few examples of large land-based geothermal systems that have been torn apart by an eruption and become inundated in this way. Scientists hope the data collected during this expedition will help them better understand how geothermal systems respond to disruptions of this kind.

“It was very gratifying to take the tools and knowledge we’ve developed for ocean research and apply them to work in the lake, especially for a scientific project with so much Maori cultural significance.”

“We hope the success in Lake Rotomahana is the first of many scientific collaborations in this part of the world where there are many interesting research problems to investigate.”

The project was a collaboration involving GNS Science, Woods Hole Oceanographic Institution in Massachusetts, Lamont-Doherty Earth Observatory at Columbia University in New York, the National Oceanic and Atmospheric Administration in Seattle, and the University of Waikato.

Filed under: Travel, world news Tagged: | Geology, Lake Rotomahana, Mount Tarawera, New Zealand, Pink and white terraces, Summit County News, Travel, underwater research, Woods Hole Oceanographic Institution