Ruapehu - IGNS - Science Alert Bulletin V96/12

June 19 1996 (Wedsnday) 1730 NZST (UT + 12)

Ruapehu Volcano

Update

Overnight the level of seismicity increased to reach a peak at
about 0100h this morning. From that time through to 0400h
seismicity declined to relatively low levels, near to those
recorded prior to this episode of activity. For most of the day
the level has remained low. About 1450-1455h this afternoon it
started to increase slightly, accompanying the formation of a
tall ash column.

No observations were made of activity over night.

Observations made on overflights today (courtesy of Taupo
District Council and TV3) indicate the crater resembles its
preeruption profile with little change. Thick deposits of
lava bombs and ash have accumulated around on the crater. Dome
Shelter remains intact, as does the seismic signal from the
shelter. During the over flights the active vent was producing a
steam and gas column to 500-800m above the summit, being blown
down wind forming a low level (5-10000 ft) haze.

The level of volcanic tremor on the Chateau record is now at its
lowest level since this episode started, but remains low
frequency in content. This suggests that molten material
continues to move into the base of the volcano. While this
activity continues, the possibility of further activity remains
high.

The alert level remains at 3.

BJ Scott for CJN Wilson  (Volcanology Programme Leader)