Photos of Ruapehu after September eruptionKEY POINTS:
Ruapehu's alert level has been downgraded following last month's eruption but there is still a high possibility of another eruption.
GNS volcano surveillance coordinator Brad Scott said there have been some volcanic tremors and the temperature of the crater lake has risen by six degrees since the eruption on September 25.
The volcano had been at level two - "minor eruptive activity" - and is now back at level one - "signs of unrest".
"We still see the possibility of an eruption as quite high. We're being pretty cautious. We're not allowing our own staff to go up there for more than 10 to 15 minutes at a time," Mr Scott said.
He said a team from GNS tried to visit the crater lake this afternoon by helicopter but the wind was too strong.
He said tramping to the crater lake right now would not be a "safe activity". Climber William Pike was staying in the Dome Shelter at the time of the eruption and later had to have one leg amputated below the knee.
Department of Conservation spokesman Dave Wakelin said people are "strongly recommended" not to tramp to the crater lake.
"But we don't have powers or arrest. Anyone is free to go anywhere," Mr Wakelin said.
Strictly speaking, the Dome shelter is not a hut and people should only stay there if it is an emergency, he said.
The hut's primary purpose is to house monitoring equipment but it is just as well Mr Pike and his friend was sleeping in it, he said.
"The irony is, if they hadn't been in there, they would have been dead," Mr Wakelin said.
He said the lake water would have sloshed up the side of the crater and sucked them into the lake.
Mr Wakelin said the hut has been damaged but has not been assessed for repair yet.
