Rotorua experiences another hydrothermal eruption
Another hydrothermal eruption in Rotorua is likely a "secondary event" of earlier activity, a volcanologist says.
GeoNet on Wednesday afternoon reported the hydrothermal eruption in Rotorua.
"We've had reports of another hydrothermal eruption at Rotorua. Our trusty volcanologist @Eruptn is heading out to take a look," the geological hazard monitoring agency said on Twitter.
There was plenty of interest in the news given on Monday morning people in Ohinemutu village were woken by eruptions coming through the lake like geysers.
We've had reports of another hydrothermal eruption at Rotorua. Our trusty volcanologist @Eruptn is heading out to take a look— GeoNet (@geonet) November 30, 2016
Eyewitness Shane Aromoana said the rumble could be heard before the eruption could be seen.
"It was just black sand going up in the air.
"It was awesome."
GNS Science volcanologist Brad Scott said the eruption was "small to very small."
"If I came here without the knowledge [it happened] I wouldn't see any evidence of it."
He said the eruption was about two metres high.
"It's what geothermal systems do. Eruptions like this are not uncommon.
"The unusual thing is it hadn't happened before."
In regards to a possible earthquake linkage, Scott isn't sure.
"How do you join those dots? I wouldn't discount it though."
There's also a lot of activity in Kuirau park at present, he said.
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On Sunday night, low-slip earthquakes were detected in Kapiti and Manawatu, adding to similar activity already seen in Gisborne and Hawke's Bay. However the earthquakes were unlikely to be related to the hydrothermal activity in Ohinemutu, said GNS duty volcanologist Tony Hurst.
"We had a report of an eruption – someone saw the lake bubbling and giving off a little eruption," Hurst said.
It would be "perfectly normal" for there to be a "secondary event" following the eruptions earlier in the week, he said.
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."
When asked if the eruptions posed any dangers to locals, Hurst said they did not, as long as they remained out in the lake.
"We've had problems in the past where they have come up in people's garages which is obviously undesirable for them."
Rotorua Lakes Council on its Facebook page said the eruption was "much smaller this time but still a spectacular sight".
"From reports the water bubbled up to about a metre in height and three metres in diameter."