Ruapehu volcano (New Zealand): minor unrest continues as lake temperature slowly increases

Te Wai ā-moe (Ruapehu Crater Lake) has begun a slow reheating, with temperatures rising by 2–3ºC since mid-October, now averaging around 10–11ºC, though still relatively low.
The lake cooled from about 30ºC in February to 8ºC by early October. During the cooling, SO₂ emissions and volcanic tremor decreased, signaling the cooling hydrothermal system and possible mineral sealing under the lake, reducing gas flow. However, SO₂ emissions continued, indicating the vent stayed partially open, as seen with weak lake upwellings and sulfur strands on the surface.

Despite the warming trend, the vent likely remains partly sealed. Significant SO2 emissions could rupture this seal, potentially causing a small eruption, though past heating phases show this is uncommon.
No deep seismic changes have been recorded, and the risk of an unexpected eruption remains low. Current signs suggest ongoing low-level unrest at Ruapehu, with expected gradual heating (around 1ºC per day) over the next months as part of the lake’s normal cycle.

Thus, The Volcaic Alert Level remains at 1 and the Aviation Colour Code at Green.

Source: GNS Science/GeoNet New Zealand volcano activity update 31 October 2024