An increase in volcanic gas emissions and sustained high lake temperature suggest a slightly higher level of activity at Mt Ruapehu. The Volcanic Alert Level remains at 1.
The recent fine weather has allowed GeoNet to make airborne gas measurements over Mt Ruapehu. These recorded high levels of CO2, SO2 and H2S emission from the Crater Lake (Te Wai Ā-Moe). The CO2 emission rate on 23rd November was 2290 tonnes/day, one of the largest values recorded in recent years. The current lake temperature is 37° C, which is near the top of its usual range and has been sustained over the past 2 months.
The data are consistent with open vent degassing of Ruapehu. Higher than usual temperatures and high gas fluxes like we have now are common in the open vent situation and have been observed in the past outside eruptive periods. Volcanic seismic tremor remains at moderate levels. The fine weather has also allowed the taking of water samples from Ruapehu Crater Lake and the analysis of these samples is underway.
GNS Science continues to closely monitor Mt Ruapehu and our other active volcanoes through the GeoNet project. The Volcanic Alert Level of Ruapehu remains at 1 and the Aviation Colour Code at Green.
Tony Hurst Duty Volcanologist