Jun 18 1996, 11:45 am - Ruapehu Volcano

A significant lava (Strombolian type) eruption occurred at Ruapehu last night between 21:00 - 22:00. The eruption was characterised by loud detonations and sprays of glowing rocks ejected above the crater. The eruption event was accompanied by strong seismicity. Since that time the level of seismicity has declined. Through to about 03:00 several discrete eruption earthquakes were recorded, but the size and number per hour has continued to decrease through to the present time.

Observations made on overflights this morning (courtesy of TVNZ and TV3) confirm that the new lake has been destroyed and the crater floor is dry. The active vent is an icecream cone shaped feature in the southern part of the crater floor. Apparently thick deposits of lava (bombs and lapilli) have accumulated on the crater floor. The bombs and blocks thrown out over night travelled further than those erupted yesterday, out to about 1.5 km from the vent. Dome Shelter remains intact, as does the seismic signal from the shelter.

Presently the active vent is producing weakly ash-charged plumes to 1000 - 2000 m above the summit, which are blown down wind forming a low level (5,000 - 10,000 feet) haze.

The level of volcanic tremor on the Chateau record remains elevated and 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.

In summary, the style and scale of activity remains similar to that in mid-October 1995.

B.J. Scott (for C.J.N. Wilson)
Volcanology Programme Leader