Ruapehu Crater Lake heating

A climber looks out to the crater lake of Mt Ruapehu and beyond.

Mount Ruapehu’s Crater Lake / Te Wai ā-moe has entered another heating phase, rising in temperature by 15 degrees Celsius in the last two months.

In July, the lake was at 11C, but has heated steadily to reach 26C recently.

GNS Science Te Pū Ao’s duty volcanologist, Cameron Asher, reported that other monitoring indicators have remained within normal ranges for such a heating episode, meaning that the Volcanic Alert Level remains at Level 1 with no disruptions to aviation in the area.

The previous lower temperatures in the lake could be due to snow melt and heavy rainfall into the lake, he said, but this would not affect long-term heating or cooling trends.

Water samples collected in August showed fluid and gas levels were within the usual range for Mount Ruapehu, and that the heating episode is happening because of new magma deep within the volcano’s system.

Again, this is not unusual for the beginning of a heating episode.

A few earthquakes have been located underneath the volcano during 2023, but seismic activity this year has generally been weak.

In all, said Asher, this meant that there is currently no raised cause for concern.

GNS reported that the Ruapehu Crater Lake's temperature has risen steadily since July. /GNS Science

“The rise of lake temperature is consistent with past heating episodes at Mt Ruapehu and continues to produce a low level of volcanic activity in the lake.”

However, he warned that this was not necessarily a forecast of what might be to come.

“Mt Ruapehu is an active volcano and has the potential to erupt with little or no warning when in a state of minor volcanic unrest.”

Hazards can still be expected during Volcanic Alert Level 1, including steam and volcanic ash discharge, volcanic gas, earthquakes, landslides and hydrothermal activity.