Mt Ruapehu crater lake temperature rising says GNS

The temperature on Mount Ruapehu's crater lake has been increasing. Photo / File

Mt Ruapehu's crater lake temperature is rising, almost doubling in just over a month, according to volcanologists at GNS.

Recent data collected from observations and temperature recordings at Mt Ruapehu show the lake temperature is sitting around 22C, up from a temperature of 12C recorded in late September. The lake is currently overflowing via an outlet within the crater.

Despite the increase, GNS science Volcanologist Brad Scott said the rise was no cause for concern.

"Typically, over periods of months, Ruapehu's crater lake has heating and cooling cycles. Since mid-October, the lake has been warming slowly and has now reached 22C," Scott said.

"These are normal observations for the start of a heating cycle."

GNS science Volcanologist Brad Scott said the rise was no cause for concern.

According to Scott, volcanic activity at the volcano remains low, with some small earthquakes and volcanic tremors recorded.

"The intensity of volcanic tremor has remained weak over the past three months, and small earthquakes continue to be located in the vicinity of Mt Ruapehu.

"None of these observations are unusual for Mt Ruapehu. All observations over the past months indicate that the volcano remains in a general state of minor unrest."

Mount Ruapehu. Photo / Ned Bullock

While Ruapehu's Volcanic Alert Level remains at 1, GNS said Ruapehu was still an active volcano and has the potential to erupt with little or no warning. The only other New Zealand volcano at Alert Level 1 is Whakaari/White Island.

GNS Science and the National Geohazards Monitoring Centre closely monitor volcanic activity at Mt Ruapehu with the GeoNet network of seismic and acoustic sensors, GPS receivers, sensors in the lake and visits to the lake area, as well as flights to collect and analyse volcanic gases.

The volcano last erupted in September 2007 without warning, with two lahars travelling down the mountain, with a seven-minute long earthquake recorded nearby.