Jun 21 1996, 3:00 pm - Ruapehu Volcano

Overnight the intensity of seismicity at Ruapehu increased slightly to levels that are similar to those recorded since the September - October 1995 eruption. Based on observations during two overflights today, the low levels continue to be related to the very open vent situation. The crater floor remains a flat area at about 120 - 150 m deep below pre-1995 lake overflow level. Volcanic gases are freely streaming through the rubble on the crater floor, to feed a white, ash-poor steam and gas column which was just clearing the summit before being blown to south by 40 knot winds.

As part of todays overflights scientist's looked for the reported fumaroles on the east crater wall and saw no sign of them. The origin of the fumarole seen on Wednesday, but not later remains uncertain. They also saw no evidence that this weeks eruption has significantly altered the eastern wall around the active crater.

As mentioned yesterday there is a lot of loose material on the northern slopes of the volcano and some of this material could remobilise if rained on. Information from NZ Metservice indicates that the freezing level will be about 2600 - 2700 m, ie. rain will fall on the volcano rather than snow. Hence some secondary lahars may occur during the rainfalls expected over the next day or so.

The level of activity at the volcano has stabilised over the last 24 - 26 hours, and longer term trends will be best evaluated after the next COSPEC data is collected. The expected rainfall will interfere with collecting that data.

The alert level remains at 3.

B.J. Scott
Volcano Surveillance Manager