People are being warned to stay clear of the crater lake at Mt Ruapehu as scientists check the safety of the vent systems.
Three ski areas on the the central North Island mountain are unaffected and remain open but the Department of Conservation has issued safety concerns because of cooler temperatures in the crater lake.
Yesterday DOC said people shouldn't go past Whakapapa Col or the Dome Shed or enter the crater from above Turoa ski area. They also shouldn't camp in the summit area.
An alert level of one has been issued for Mt Ruapehu. The level ranges from zero to five and one indicates minor unrest.
There was only a small chance an eruption could occur .
