Oct 14 1995, 5:30 pm - Ruapehu Volcano

Situation Summary

As of 17:30 the situation is as follows:

• Volcanic tremor continued at fluctuating but generally low levels during most of the last 24 hours. The tremor record from the Dome (summit) instrument has been strongly banded into intervals of relatively high and low tremor. Two small (M1 - M1.5) volcanic earthquakes were recorded at 04:34 and 06:34 today. A period of more intense tremor commenced at 15:50 today, and had increased to moderate to strong levels by 16:30. This increased tremor is accompanied by vigorous ash emission. This situation is developing at present.

• Bad weather has prevented ground observations of Ruapehu, and no field work at the volcano has been carried out by GNS staff. An aircraft reported sighting an ash plume from the volcano at c. 07:00 today. CAA has received reports of other aircraft encountering ash at various locations including near Taupo and Hastings. We are presently receiving reports of heavy ash fall at Waiouru, and large plumes seen from aircraft.

• Observations of the crater yesterday afternoon showed intermittent ash eruptions from the deep southern vent in the now dry crater basin, with mostly steam and gas emitted from the not clearly observed northern vent. This was the reverse of the situation observed during the overflight yesterday morning, suggesting alternation of the ash emission vents.

Summary and Alert Status

The present eruption episode is continuing. From 16:30 today tremor levels have reached levels last seen during the October 11 - 12 eruption. We advise that the Alert Level presently remains at 3, but is under hourly review.

I.A. Nairn (for C.J.N. Wilson)
Volcanology Programme Manager