Mar 7 2011, 4:00 pm - Ruapehu Volcano

Mount Ruapehu is currently in a heating cycle and the Crater Lake temperature is now 40 °C. Other monitored indicators including gas output, seismic activity, lake chemistry and ground deformation have shown variable trends in recent weeks. These demonstrate typical behaviour for Ruapehu during a lake heating cycle. The Volcanic Alert Level remains at Level 1.

In October 2010 Ruapehu Crater Lake began its current heating cycle, the eighth since the lake was re-established in 2002 after the 1995 - 1996 eruptions. The temperature of the lake has now reached 40 °C, the third highest temperature recorded since the re-establishment of the lake. The highest recorded temperature since 2002 was 42.5 °C in May 2003.

Associated with the current heating cycle have been small changes in lake chemistry and minor seismic activity.

These observations are consistent with the volcano-hydrothermal system now being more active and heating the Crater Lake water. The current activity could result in the lake temperature continuing to rise and the lake colour may change if sediments on the lake floor are disturbed by the increased gas and heat flow into the lake. If atmospheric conditions are suitable, steam may also be seen above the Crater Lake. The current observations are within the normal range for Ruapehu.

GeoNet scientists continue to monitor this and other volcanoes.

Ruapehu remains an active volcano and future eruptions may occur without warning.

The Volcanic Alert Level remains at Level 1 (Departure from typical background surface activity, signs of unrest).

Volcanic Aviation Code remains Green (Volcano is in normal, non-eruptive state).

Tony Hurst
GeoNet Duty Volcanologist

Brad Scott
Volcano Surveillance Coordinator