article: Oct 4 2007 - Mt Ruapehu activity update

GNS scientists are continuing to monitor the activity at Ruapehu since the eruption last week on September 25.

View of the summit area of Mt Ruapehu on September 26 showing ash deposits from the eruption on September 25. Recent snow fall has completely covered the ash deposits (compare with picture below taken on October 4).

View of the summit area of Mt Ruapehu on October 4. Recent snow fall has completely covered the deposits from September 25 (compare with picture above taken on September 26).

GNS scientists are continuing to monitor the activity at Ruapehu since the eruption last week on September 25. A surveillance flight over Mt Ruapehu was made today during a break in the weather. Good views of the crater lake were obtained. The surface of the lake was very calm with no evidence of strong degassing. The recent snowfall has covered the deposits from last week’s eruption.

An airborne survey to analyse gases in the volcanic plume was also completed. Preliminary analysis of the data suggests that the fluxes of sulphur dioxide and carbon dioxide from the volcano are low; this means that there is probably no new magma at shallow depths in the volcano.

GNS scientist Karen Britten said that conditions were close to ideal for both observations and gas measurements.

Analysis of water samples taken on Friday September 28 shows that there has been no major change in the chemistry of the crater lake. A slight increase in magnesium is consistent with vent fluids being injected into the lake after the eruption.

Seismicity has remained low since the eruption on September 25; the only significant event over the last week has been a smaller volcanic earthquake on Saturday September 29.

We advise people to follow Department of Conservation guidelines for access to the mountain.

The Alert Level remains at 2 (minor eruptive activity) and will continue to be re-assessed regularly.