Ruapehu - IGNS - Science Alert Bulletin V95/43

Sunday 15 October 1995
1030 hours NZDT (UT +13)
Ruapehu Volcanic Activity

*     Observations have confirmed that the period of tremor recorded last
night between 1550 and 2030 hours was one of the most intense intervals of
activity during the 1995 eruption to date.  Tremor levels were 2 to 3
times that recorded on the evening of 11 October when the largest ash fall
to date was recorded.   The diagram on the next page shows the relative
levels of energy released as measured by our seismometer at Whakapapa
village.  Since 2030 hours last night, the level of tremor has reduced,
and stayed at low to moderate levels since.

*     The accompanying eruptions last night  produced voluminous amounts
of ash which was blown in a narrow tongue to the SSE by strong NNW winds.
This tongue was centred north of Waiouru.  Ash fall was recorded at
Dannevirke, Waipukurau, Waipawa, and Takapau, but observations have been
hampered by bad weather.

*     The Institute has field parties collecting samples from the 14
October ash fall for analysis, for comparison with the ash from the last
major eruptions on Wednesday night and Thursday morning

Summary and Alert Status

The present eruption episode is continuing at a reduced level relative to
Saturday evening.  We advise that the Alert Level remains at 3.

Dr CJN Wilson, Programme Leader, Volcanology