Nov 1 2005, 3:00 pm - Ruapehu Volcano

Recent Crater Lake visits have recorded a rise in the temperature of the lake. On 12 October the temperature was 30°C, however on 24 and 27 October it had risen to 35 - 36°C. We had previously reported a decline that appeared to mark the end of the previous heating episode, which peaked in September 2005 at 38°C. However, the recent rise in temperature suggests that lake heating has recommenced.

Cycles of heating and cooling are common at Ruapehu, with the lake temperature ranging from about 15 to 40°C, occurring every 9 - 12 months and typically lasting 1 - 3 months.

As the lake warms, steam plumes may be observed under favourable conditions (cool, calm days). Plumes have been observed on 24 October and 1 November.
Seismic activity continues at about normal levels for Ruapehu, except for a slight increase in the occurrence of volcanic earthquakes over the last 2 weeks.

The Alert Level for Ruapehu remains at Alert Level 1, as there is no change in activity.

Brad Scott
Volcano Surveillance Co-ordinator