Ruapehu volcano (New Zealand): Crater Lake remains at 20 °C

Since the last update, temperatures at Te Wai ā-moe (Ruapehu Crater Lake) have remained around 20 ºC.
Heat flux modeling indicates that this corresponds to a steady heat input of approximately 100 MW for most of the past two months. Typically, heat input ranges from about 50 MW to over 300–400 MW when the lake reaches higher temperatures (above 35 °C).
During this period, volcanic tremor has remained low with 9 earthquakes beneath the summit—an expected number for this timeframe.
Continuous gas emission measurements indicate a steady sulfur dioxide flux of approximately 100–150 tonnes per day, with high flux rates occasionally exceeding 500 tonnes per day. These observations suggest that minor volcanic activity continues to supply heat to the Crater Lake. However, the lake has not warmed as much as it typically does during a heating cycle. The ongoing gas flow through the lake indicates that the vents remain partially open.
Water samples collected from the lake on 4 February 2025 show a dilution trend, which is typical in summer due to increased meltwater inflow. This aligns with the relatively low levels of gas and concentrated fluid input.
The Volcanic Alert Level remains at 1, and the Aviation Colour Code remains Green.

Source: GNS Science/GeoNet New Zealand volcano activity update 28 February 2025