Two walking tracks near Mt Tongariro will reopen tomorrow following the mountain's eruption on Monday night, the Department of Conservation says.

However, it is too early to say when the popular Tongariro Alpine Crossing track will reopen.

Department of Conservation (DOC) staff flew over the volcano, which erupted for the first time in more than a century shortly before midnight on Monday, to check the site of the eruption.

It was the first time staff were able to get a close look at the damage to the mountain, and DOC's Ketetahi Hut.


DOC Ruapehu area manager Nic Peet said debris from the eruption had dammed three small tributaries of the Mangatipua Stream.

"DOC also faces significant work in assessing the damage to the track and Ketetahi Hut," he said.

Today's flyover confirmed the damage was localised to Mt Tongariro, within the Tongariro National Park, he said.

Mr Peet said at 8am tomorrow the Tama Lakes track from Whakapapa Village to Waihohonu Hut would reopen, along with the Taranaki Falls loop track.

However, the main Tongariro Alpine Crossing track, which at times passes within a kilometre of the eruption site, would remain closed.

"We need to be satisfied the volcanic threat has eased before this track re-opens and we will take advice from the GNS experts on this.

"We are keen to get people back onto the Tongariro Crossing but we need to make sure the volcano has settled down first," he said."

Mt Ruapehu and its skifields were unaffected by the eruption.