Sep 20 2000, 12:30 pm - White Island Volcano

Staff from the Institute of Geological & Nuclear Sciences (GNS) visited White Island yesterday (Tuesday, September 19) to make monitoring observations and to assess the volcano status. The volcano has ceased to produce ash although the normal emission of steam and gas continues. This lower level of activity is sufficient to decrease the Alert Level from 2 to 1.

The Alert Level for White Island was set to Level 2 on 19 April 2000 after it began to emit significant quantities of ash, some of which reached the mainland. Ash has continued to be produced from the MH vent at irregular intervals since then, and the ash plume frequently extended for tens of kilometres downwind. From April to June, the ash emission was accompanied by a moderate level of seismic activity, but there was little correlation between the seismic activity and the amount of ash or steam coming from the volcano.

Ash emission continued during June and July, a short-lived magmatic eruption accompanied by strong seismicity produced a new explosion crater on 27 July 2000. After this ash emission occurred from both active vents, however the ash content of the plume declined significantly in late August - early September. There is no sign that the current vents of White Island have recently emitted any ash. MH vent continues to emit steam and gas, but it is now within the range of the normal fumarolic activity of White Island.

Based on recent observations, the current low level of seismic activity and the lack of ash emission this is sufficient to decrease the Alert Level to Level 1.

The lower level of activity does not mean that there is no volcanic hazard to visitors to White Island. Past activity indicates that eruptions, such as that which occurred on 27 July, could occur with little or no warning, even when the Alert Level is 1. Caution should always be exercised when visiting the island.

GNS volcanologists will continue to closely monitor activity at White Island and further updates will be issued as necessary.

Brent Alloway
Chief Volcanologist