According to recent data and observations collected by volcanologists at GNS from the Mt Ruapehu crater lake (Te Wai ā-moe), the lake temperature has almost doubled in just over a month.
GNS Science and the National Geohazards Monitoring Centre monitored the volcano activity 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 temperature was recorded and shows that the lake is currently at 22oC and still rising, which is double from the month of September which stood at 12oC. 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 and that the volcanic activity at Mt Ruapehu remains low, with the Volcanic Alert Level remaining at Level 1, with some small earthquakes and volcanic tremors recorded.
Scott explained that; "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 22oC. These are normal observations for the start of a heating cycle. 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."
Scott stated that there were no significant changes in the makeup of the lake waters as the pH remains at 0.8, having ranged between 0.7 and 0.9 over the last six years.
"Our interpretation of these observations is that the underlying vent areas are open to volcanic gases and geothermal fluids entering the lake and reacting with rock in the vents. 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," he concluded.
All studies and observations done over the past months, indicates that the volcano remains in a general state of minor unrest.