There has been another eruption in Lake Rotorua, near the site of Monday's hydrothermal eruption.
GNS volcanologist Brad Scott said Ohinemutu was a relatively active geothermal area.
He said these types of eruptions hadn't happened for several years but were common in Ohinemutu's history.
He believed today's eruption was smaller than the one on Monday morning, which shot water about 20-30m in the air. Water today reached about 1m to 2m high, he said.
"It's not unusual for a second smaller one to follow [a bigger eruption].
"It is what geothermal systems do."
Mr Scott was measuring temperatures this afternoon but said there was not too much GNS could do.
"The main thing is now that I know where the site is I feel pretty comfortable it's well away from the houses."
Mr Scott was advising people to avoid getting too close to the water's edge and to stay back at the carpark.
He said there had been some changes in the natural geothermal pools around Rotorua - with a couple of pools at Whakarewarewa declining and Kuirau Lake flowing strongly.
Hohepa Timihou was working on a house next to Tunohopu Marae when he heard a relative shout out about the eruption. He ran towards it and captured the eruption on video.
"My aunty was up the hill looking down and she told me to run down and have a look.
"We ran down to it and got too close I think."
He said his first reaction was to video it.
"The ground was shaking and all of that ... You would hear the rumble first then see the water drop in the lake and then shoot up into the air.
"We are used to all that ngawha (geyser) activity here but this was quite neat, it was quite different for around here."
Mr Timihou acknowledged it was a bit scary and locals in the village were on tenterhooks.
"I think we are all a little bit worried to be honest."
Ohinemutu resident Lani Kereopa, who saw Monday morning's eruption, said family members had seen today's one.
She was concerned by the second eruption, and that the Utuhina River had changed colour to a "thick, chocolate" brown on Tuesday - which she believed might have been related to the geothermal activity.
Ms Kereopa said she didn't feel entirely comfortable staying in the village, but didn't want to burden others.
Heather Thompson told the Rotorua Daily Post she saw the lake bubbling and "giving off a little eruption down at Ohinemutu" this afternoon.
She said she was at Rotorua Hospital when she noticed "movement that caught my eye" from the bay.
"There was an area that was really bubbling up, like mud and water."
She wasn't sure how long it had been going on, but she watched it for about a minute before it finished.
"It was probably going as high as the fence down there."
In a post on its Facebook page Rotorua Lakes Council said the eruption was "much smaller this time but still a spectacular sight".
The council said a sudden drop in air pressure may have caused the eruption.
"It is unknown if it's connected to Monday's eruption but is believed to have been caused by a sudden drop in air pressure at 3pm today, that would have been like lifting a weight off the ground."
Shane Aramoana said he heard the rumbling before he saw the eruption.
He said it looked almost like black sand coming up.
Mr Aramoana is staying at the marae at Ohinemutu with a group of children from an Auckland kohanga reo.
"You hear the eruption before you see it."
Mr Aramoana said it was "awesome".
Another with the group, Tarquin Elliott, said they had taken the children to see the geysers at Te Puia this morning - but didn't expect one across the road from where they were staying.