Geothermal activity has boiled over on a traffic island in Rotorua on Wednesday morning.
Geothermal inspector Peter Brownbridge said the cause of the activity on Lake Rd is unknown and the area isn't known for fumaroles (openings in the earth's surface that emit steam and volcanic gases).
Brownbridge said the fumarole isn't particularly large and it "popped up" amongst plants.
"There’s a fair bit of water and mud on the road on the side going into town so we’ve closed that off for now," he said.
There is a crack across both lanes on the other side of the road but it is not yet known if this is related to the eruption.
“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 have been shut down to see if has an effect on what’s happening here, in which case it could be bore-related. 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 are removing the mud coming out of the fumarole and onto the road to prevent it reaching a nearby stream.
Brownbridge also said a cesspit drain in the area has been blocked off, also to stop mud from getting into the stream.