alert bulletin: Oct 4 2007, 3:00 pm - Ruapehu Volcano

Science Alert Bulletin RUA-07/07 - Ruapehu volcanic activity update: Science Alert Level remains at 2

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

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.

An airborne survey to analyse gases in the volcanic plume was flown earlier today. 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.

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.

Further observations and images are available.