Slight changes in water and gas composition of the Crater Lake (Te Wai ā-Moe) at Mt Ruapehu 

Measured changes in crater lake water and gas composition confirm the slightly elevated level of activity at Mt Ruapehu. The lake temperature (37ºC) and the level of seismic tremor remain unchanged. The Volcanic Alert Level remains at 1.
The Crater lake (Te Wai ā-Moe) was visited to sample water and gas on 10 and 17 November 2017. The results from the analyses show a slight increase in Chloride, Sulphate and Magnesium concentrations, and CO-CO2 gas ratio. These changes are consistent with the increase in CO2, SO2 and H2S emission rates measured on 23 November and the sustained high lake temperature (~37ºC) reported in our latest bulletin on Saturday 25 November 2017.
The increase in concentration of these chemical elements, higher gas output and a sustained high lake temperature all suggest a more open pathway for the volcanic gases from depth to the surface. These increases are common in periods of higher lake temperature and have been observed in the past outside eruptive periods. Volcanic seismic tremor is currently at moderate to low levels. Further sampling of the Crater Lake and a gas measurement flight are planned as weather allows.
As weather cleared out overnight, a small steam plume was visible this morning above the crater lake at Ruapehu. Such steam plumes are to be expected due to the current combination of higher lake temperature, gas emissions and atmospheric humidity.
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.
Agnes Mazot
Duty Volcanologist

Posted by 28 November 2017 18:50:00

High volcanic gas emission and Crater Lake (Te Wai ā-Moe) temperature at Mt Ruapehu 

No change to Volcanic Alert Level
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

Posted by 25 November 2017 12:16:00