Volcanic mountains

Rising temperatures at Mount Ruapehu crater lake raise volcanic alert level

The rise in temperature is accompanied by high levels of volcanic tremors. Photo / Geonet

Mount Ruapehu has been moved to Volcanic Alert Level 2 following rising temperatures in its crater lake.

The lake undergoes cycles of heating and cooling over a period of several months. A new heating cycle has begun with temperatures reaching 31C.

The rise in temperature is accompanied by high levels of volcanic tremors.

The last time Mount Ruapehu was moved to Volcanic Level 2 was in December 2020.

GNS Science volcanologist Craig Miller said there is an increased likelihood of eruptive activity as a strong tremor indicates increased gas flow through the system.

“Despite an increase in gas flow, the temperature of the lake reacts only slowly, suggesting that a partial blockage may exist in the vent below the lake. This could allow pressure to build up in the volcano. “

Volcanic Alert Level 2 indicates that the main hazards are those expected during volcanic unrest; steam discharge, volcanic gases, earthquakes, landslides and hydrothermal activity.

Although Volcanic Alert Level 2 is primarily associated with the risk of volcanic unrest, eruptions can still occur with little or no warning.

Miller said the lake is currently overflowing into the Whangaehu River, but the level of flow is considered minor.

“The color of the lake is expected to change to a darker gray color as sediments at the bottom of the lake are disturbed by the influx of warm fluids warming the lake.”

The aviation color code remains green.