Work may begin tomorrow to quench geothermal activity that erupted through Lake Rd this morning, spewing out mud, steam and water.
In an afternoon statement, Rotorua Lakes Council said investigations into what caused the fumarole — a steam-driven vent — to emerge would continue tomorrow.
It had not yet been linked to a geothermal bore. If the activity is not bore-related, it was likely work will start to quench and fill the fumarole tomorrow, the statement said.
Traffic management would continue. As of tonight, Lake Rd heading out of the CBD was down to one lane, and both lanes were closed in the other direction with a diversion via Tarewa Rd. Pedestrians were advised to stay away.
The activity was located in the garden in the median strip on Lake Rd near the geothermally active Kuirau Park.
The council earlier said the cause was likely to be linked to high groundwater levels which are weather-driven.
Its geothermal inspector, Peter Brownbridge, said the area was not a known hot spot for fumaroles and the council had not had any previous reports of hot springs there.
The cause of the fumarole was unknown, he said.
The fumarole was not large and it popped up among plantings in the middle of a traffic island but there was a fair bit of water and mud on the road on the side going into town which had been closed off.
Brownbridge said it was unknown if a crack across both lanes on the other side of the road was related to the fumarole.
"We're not detecting any heat or movement from the crack so that side of the road remains open for now."
Brownbridge said some geothermal bores in the area had been shut down to see if it had an impact on what was happening at the site.
"We have well drillers here now looking to quench one of the bores to see if that affects the flow of water coming out of the fumarole."
Sucker trucks had been called in to remove the mud that is coming out of the fumarole and onto the road to prevent it from getting into the nearby stream.
A cesspit drain in the area had also been blocked off for the same reason.
A woman watching the action this morning said she arrived just as the work crews did.
"It had exploded and mud came out. It's cracked the road."
She had not seen anything like it in the area before.
Rotorua woman Liz Coppard was driving past the area and spotted what she described as a borehole that had opened up.
She said it was about 1m tall and bubbling up from the garden in the median strip of Lake Rd.
"It's right in between two power poles so not sure if that will cause any electrical issues."
She said there were about eight Infracore workers in the area with high-visibility vests on but traffic was still flowing on Lake Rd.