article: Jul 28 2010 - Ruapehu temperature and gas changes continue

GeoNet continues to monitor regular changes at Mount Ruapehu in volcanic gas output and the temperature of the Crater Lake.

GeoNet scientists measure carbon dioxide, sulphur dioxide and hydrogen sulphide (CO₂, SO₂ and H₂S respectively) at least once a month by flying a fixed-wing aircraft through the volcanic plume. Scientists also visit Crater Lake to collect water samples and measure the temperature of the lake. A data logger records the temperature and water level and this is transmitted automatically to the GeoNet team as well.

Over the past 10 years (see diagram below), we have recorded distinct heating cycles when the Crater Lake temperature has increased from lows of less than 15 °C to highs of over 40 °C. These cycles are typically 12 - 18 months long and are often associated with increased gas output from the volcano.

During the May - June 2010 period, the Crater Lake heated up from 20 °C to over 30 °C and a recent gas survey on 12 July indicates higher CO₂ gas levels. New data, analysed through research funded by the Foundation for Research, Science and Technology (FRST), show that there is a relationship with increasing temperature cycles and higher CO₂ outputs from the Crater Lake. The current heating cycle also appears to following this trend.

This cycling is normal for Ruapehu Crater Lake and there are no indications that an eruption is more likely during hotter periods.

Graph showing temperatures at Ruapehu's Crater Lake for the past 8 years.