Jul 5 1996, 2:00 pm - Ruapehu Volcano

Seismic activity recorded from Dome today has remained at levels similar to those of yesterday and the last week. Cloud about the summit of Ruapehu is associated with strong south-east winds which have largely obscured the Whakapapa (CNZ) seismic record. The wind and cloud has prevented the COSPEC gas discharge measurement flight planned for today. Intermittent minor ash eruptions are continuing, as demonstrated by new ash darkening the overnight snowfall on Paretetaitonga and the west Pare ridge. A narrow ash fallout zone extends down to the Bruce Road.

It has been 8 days since the last moderate-sized ash eruption which occurred on Thursday 27 June. Only relatively minor ash emissions have occurred since then. The gas plume visually observed on the 3 July crater inspection flight appeared to be less voluminous than during previous observations. Despite lack of the planned COSPEC gas discharge measurement, the present level of eruptive activity does not justify continuation of Science Alert Level 3 ("Significant local eruption in progress"), and the Alert Level has been lowered to 2 ("Minor eruptive activity"). A COSPEC flight will be carried out as soon as possible.

It is important to note that this lowering of the Alert Level from 3 to 2 does not mean that eruptions at Ruapehu have ended. With the magma column present at shallow depth beneath the crater floor, and continuing shallow seismic activity and moderate-strong gas emission, further ash eruptions can be expected, most likely similar to those which have occurred during the past week (July 1 - 5). Depending on wind direction, minor ashfalls onto the ski fields are likely to continue (although with lower probability than during the June 17 - 28 period). For these reasons we are making no change to the GNS hazard zones around the the crater (including the 2 km Red zone), until further notice.

The Alert Level is now set at 2. At this level there will be no rostered weekend or evening monitoring of the volcano by GNS staff, and surveillance will return to routine levels.

Ian Nairn (for Colin Wilson)
Volcanology Progamme Leader