Rotorua was rocked by its second hydrothermal eruption in three days on Wednesday afternoon, with another geyser erupting in Lake Rotorua.
GeoNet Science volcanologist Brad Scott attended the eruption in the shallows of a small bay at Onihemutu, which he was alerted to by multiple reports from people in the area.
He told Newshub that from what he'd heard, the eruption was "pretty small" - and that was backed up by what he saw when he visited.
"The only thing I can ascertain positively is that it's very small. I wouldn't have known anything had happened if I hadn't been told," he said.
The eruption occurred in a similar spot to a larger hydrothermal eruption on Monday, but Rotorua Lakes Council says it's not yet known whether the two are connected.
"The eruption was much smaller this time but still a spectacular sight," the council told its Facebook followers.
"From reports the water bubbled up to about a metre in height and 3 metres in diameter."
Dr Scott said that the activity was unlikely to have much to do with the 7.8-magnitude earthquake that battered New Zealand a couple of weeks ago.
"It may be related to the Kaikoura quakes, but it's pretty hard to connect those dots two weeks afterwards. I can't discount that but it's certainly hard to make that link."
He said it's hard to say what triggered it, but explained that it was probably more likely to be related to a "perturbation of the Rotorua geothermal system".
"What I've just become aware of is that there's a significant drop in the barometer [an instrument used to measure atmospheric pressure] at the time of the eruption, and that's a real classic for triggering eruptions," he said.
Dr Scott says people should be cautious, and stay at least 100m from where the geyser activity for the time being as more eruptions may occur.
"I expect we may see some more small activity - it's re-erupted today, a few days after the original one - and I guess we could see some more," he explained.
On Monday locals had an early wake-up call after a geyser erupted in Lake Rotorua several hundred metres offshore, shooting water 20-30 metres in the air around 4am near Ohinemutu.
Geothermal inspector on Monday told Newshub while that eruption was noisy, there was nothing to worry about.
"It must have been quite powerful to throw up a big column of water as it did, but it's nothing for people to be concerned about," he said.
"We don't see many bigger ones these days although eruptions like this were quite common about eight years ago."