Long-awaited geyser recovery delights scientists

10 October 2013
GNS Science

One of Rotorua’s most iconic geysers is showing signs of rejuvenation after being dormant for 34 years. Papakura Geyser at Whakarewarewa (Te Puia) was once known for its spectacular and continuous hot water eruptions which reached heights of 2-3 metres. However, its failure in 1979 lead to the enforced closure of dozens of hot water bores in Rotorua in 1992.

Since 1979 Papakura has not had an eruption, vent temperatures have been cool, and scientists have detected less geothermal fluids inside the geyser vent.

During a recent monitoring visit, GNS Science staff Duncan Graham and Liam O’Halloran found evidence that the geyser may be returning to its former magnificence. A pool that had been cool for 20-plus years had erupted and was overflowing at 97 degrees Celsius.

"The signs we saw are very encouraging," said Volcanologist Brad Scott, one of the GNS Science team who have worked on the Rotorua Geothermal System since the bore closures in the 1990s.

GNS Science is involved in two significant projects at Rotorua. The first is a programme of monthly monitoring of 40 selected geothermal surface features for the Bay of Plenty Regional Council. This work is conducted as part of the management plan for the Rotorua Geothermal System.

The second project is a long-term research programme focused on the shallow geo-hydrology and chemistry of the Rotorua Geothermal System, lead by geochemist Ed Mroczek .

“The bore closure programme of the 1990’s has created a unique opportunity to study the recovery of an exploited geothermal system,” said Dr Mroczek.

“There has been very positive recovery of geothermal surface features in the northern portion of the Rotorua Geothermal system at Kuirau and Ohinemutu, but it has not been so clear in the Whakarewarewa-Te Puia area.

“With careful management and appropriate technologies, you can have both use and protection of the geothermal features for the economic benefit of Rotorua and the country.”

Dr Mroczek said that elevated levels of chloride geothermal fluid in the hot water at Whakarewarewa indicated that pressure had increased and water from deeper in the earth was being pushed toward the surface.
Scientists had also noticed an increase in geothermal water coming into the ‘throat’ of geyser features like Waikite, Wairoa and Papakura over the past year or so.

"This is a promising sign. Our monitoring has shown that not all geysers and springs have returned to their former state, but it is really encouraging to see signs of activity at several features," Dr Mroczek said.

The GNS Science team were all very passionate about the geothermal features and witnessing signs of recovery at Papakura Geyser was a career highlight, said Brad Scott. “To be involved with the IWI and Regional Council at this time is special.”

Dr Mroczek believed the decline of the Whakarewarewa geyser field showed how close we came to destroying New Zealand's geysers. However, careful management by IWI and the Council, in conjunction with GNS Science monitoring, had shown it was possible to use the geothermal resources in a sustainable way.
Contact: Brad Scott, Volcanologist, GNS Science, P:07-3748211

Papakura Geyser

Background
Scientist’s associated with the large-scale geothermal developments from the 1950’s to 1970’s in New Zealand observed the use of production bores stopped the flow of hot geothermal fluid to the surface. This was observed at places like Wairakei, the Spa, and Ohaaki. Hot springs and geysers vanished as bores proliferated.

Since the 1950s, an increase in the number of bores in Rotorua has contributed to a decline of many geysers, such as the Waikite, Te Horu and Papakura and other overflowing hot springs.

Retired Rotorua scientist Ted Lloyd said during the 1960s and 1970s people were able to see the steam plumes from the geysers coming up through the fog on winter mornings in Rototua. Over an 18-month period in 1978-1979 he noticed many geysers had stopped.

"Waikite and Papakura geysers had stopped, and for me, this was a wakeup call because they had never been known to stop for a long period."

As a result of the decline, scientists advocated closing down many bores during the 1980s because they were detracting from Rotorua's natural thermal attractions.

They achieved the closure of about 300 bores within a 1.5 km radius of Whakarewarewa, despite strong resistance from some bore owners. The Regional Council then implemented the Rotorua Geothermal Management Plan to manage the future recovery of the Rotorua system.
END