Volcano activity sparks warning at New Zealand visitor attraction

Visitors to one of New Zealand's scenic volcanoes have been warned to stay clear of the summit after it showed increased signs of possibility of erupting.

The government's GeoNet monitoring service on Wednesday said the output of volcanic gas from the crater lake on Mount Ruapehu, in the central North Island, was up and the lake water temperature was up from 25 degrees centigrade in April to 45 degrees centigrade in the last two days.

"Taken together these data now indicate more volcanic unrest at Mt Ruapehu. The increased gas output coupled with high heat flow and volcanic tremor imply a higher likelihood of activity," volcanologist Brad Scott said in a statement.

GeoNet had raised Ruapehu's volcanic alert level to level 2, indicating moderate to heightened unrest, and aircraft were being warned of increased activity.

The Department of Conservation (DOC) on Wednesday warned climbers and hikers against entering the "summit hazard zone" and area within 2 kilometers of the crater lake until further notice.

DOC operations manager Paul Carr said in a statement that it was important to remember Ruapehu was always active and went through periods of activity, and therefore was being constantly monitored.

The eruption detection and lahar warning systems operated by the department were all fully operational and continued to be tested regularly.

Ruapehu, part of the central North Island's volcanic belt and a major ski resort, last showed signs of heightened unrest in 2012 and it erupted in 1988, 2006 and 2007. Endit