The Volcanic Alert Level for Mount Ruapehu has been raised to 2 and the Aviation Color Code to Yellow on December 21, 2020, following an increase in Crater Lake temperature and the largest measured gas output in the past two decades. The Volcanic Alert Level reflects the current level of volcanic unrest or activity and is not a forecast of future activity, GNS Science Duty Volcanologist Mike Rosenberg said. The Crater Lake (Te Wai ?-moe) temperature has been rising and is now at 43 °C (109 °F), Rosenberg noted in a bulletin issued December 21.
During a gas flight last week, the lake was observed to be a uniform grey color which shows it is well-mixed. There is some flow over the outlet.
The gas output through the crater lake has also increased markedly in response to this heating cycle.