Another hydrothermal eruption in Lake Rotorua, New Zealand

Another hydrothermal eruption in Lake Rotorua, New Zealand

Another hydrothermal eruption occurred in New Zealand's Lake Rotorua on Wednesday, November 30, 2016, following the first one on Monday, November 28. This eruption was, however, caught on camera.

Today's eruption also occurred in the village of Ohinemutu. It was smaller than Monday's, with water reaching about 1 to 2 m (3.3 to 6.6 feet) in height, and was about 3 m (10 feet) in diameter. On Monday, the eruption shot water about 20 to 30 m (65 to 100 feet) in the air.

GNS volcanologist Brad Scott said Ohinemutu was a relatively active geothermal area and added these types of eruptions hadn't happened for several years but were common in Ohinemutu's history.

Hydrothermal eruption in Lake Rotorua on November 30, 2016

"It's not unusual for a second smaller one to follow a bigger eruption," he said. "It's what geothermal systems do."

After measuring the temperatures today, Scott added there was not much GNS can do. "The main thing is now that I know where the site is, I feel pretty comfortable it's well away from the houses."

Residents are advised to avoid getting too close to the water's edge.

Mr. Hohepa Timihout, the man who filmed today's eruption, has lived in Ohinemutu his whole life. He said he never saw something like this happening. See his statements in the video below:

On Sunday night, November 27, low-slip earthquakes were detected in Kapiti and Manawatu, adding to the similar activity already seen in Gisborne and Hawke's Bay, Stuff.co.nz reports. However, the earthquakes were unlikely to be related to the hydrothermal activity in Ohinemutu, said GNS duty volcanologist Tony Hurst.

While it was possible the shakes around Rotorua from earthquakes in Kaikoura could have disturbed the hydrothermal area, it was more likely the area was simply experiencing built-up pressure.

"It decided this week was the week to let it off. This is always occurring in Rotorua. Every year or two there will be some area that decides to be a bit more active."

Hurst said the eruptions pose no danger to the people as long as they remain out in the lake.

Geological summary

The 22-km-wide Rotorua caldera is the NW-most caldera of the Taupo volcanic zone. It is the only single-event caldera in the Taupo Volcanic Zone and was formed about 220,000 years ago following eruption of the >340 cu km rhyolitic Mamaku Ignimbrite. Although caldera collapse occurred in a single event, the process was complex and involved multiple collapse blocks.

The major city of Rotorua lies at the south end of the lake that fills much of the caldera. Post-collapse eruptive activity, which ceased during the Pleistocene, was restricted to lava dome extrusion without major explosive activity. The youngest activity consisted of the eruption of three lava domes less than 25,000 years ago. The major thermal areas of Takeke, Tikitere, Lake Rotokawa, and Rotorua-Whakarewarewa are located within the caldera or outside its rim, and the city of Rotorua lies within and adjacent to active geothermal fields. (GVP)

Featured image credit: Lake Rotorua hydrothermal eruption on November 30, 2016. Credit Hohepa Timihout.

Tags: lake rotorua

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