On April 10th we reported the lake temperature was rising and the tremor intensity was moderate. The lake temperature reached a peak of 44 °C on 19th April and is now 39 °C and continues to cool. The level of volcanic tremor has declined since 16th April and is now classified as weak.

In early April the lake temperature was trending towards a range thought to be associated with higher probabilities of an eruption. These probabilities are based on our understanding of Ruapehu’s long term relationship between volcanic activity and the lake temperature. The decreasing lake temperature indicates we are now moving away from this range of higher probability of eruption in the short term.

Last week some small steam plumes were observed above the lake. These can still be expected while the lake remains relatively warm and the air temperature cools as winter approaches.

Volcano Alert Level 1 corresponds to minor unrest. While this is the case, it is a useful reminder that eruptions can occur with little or no warning. GNS Science continues to closely monitor Mt Ruapehu and our other active volcanoes and will provide further information when conditions change.

Craig Miller Duty Volcanologist

Media Contact: Brad Scott
(07 3748211)