Ruapehu - IGNS - Science Alert Bulletin V95/31

Thursday 5 October 1995 
17.00 hours NZDT (UT +13)
Ruapehu Volcanic Activity 

Situation Summary

As of 17.00 hours the situation is as follows.

*     Volcanic seismicity was at low levels during the early part of the
day. At 1128hr a M3.0 eruption earthquake was recorded.  The level of
volcanic tremor has gradually increased since the eruption earthquake to
above pre-eruption levels.

*     Weather conditions have prevented any good views of the volcano
today. There was no observational over flight.

*     The eruption earthquake at 1128h is inferred to have accompanied an
eruption column, as ash fall was reported by a University field party in
the Kariori Forest area about 1200h.

*     Institute field parties have been active on the eastern flank of the
volcano, continuing work on the lahar deposits reported yesterday. A
COSPEC flight was undertaken yesterday collecting by far the best data set
to date. The calculated daily output of SO2 is estimated as 430 tons/day.
This should not be read as a significant increase over values reported in
the past few days. The increase is more an artefact of the better data
set, reflecting a longer sampling time, hence more variations in activity
are covered. The installation of two deformation monitoring lines was
completed.

Conclusions and Alert status

Mild eruptive activity is continuing from the volcano.  Small
explosive eruptions have continued today and the Alert Level
remains at 3. 

BJ Scott for
Dr C J N Wilson, Programme Leader, Volcanology.