Mar 30 1998, 1:30 pm - White Island Volcano

Over the last 2 - 3 weeks tour operators at White Island have reported changes within 1978-90 Crater Complex. In particular the crater lake has been drying out, and large fumaroles have formed on the crater floor. The stronger activity has been focused in an area where vents were active in May 1991. The gas and steam plume from the island has changed to a yellow colour during this time, and sounds (rumbles, bangs) have been heard offshore of the island.

A COSPEC flight was made on March 20 and recorded only 140 tons per day of SO₂ gas output. This is one of the lowest measurements to date.

On Friday March 27 volcanic tremor levels increased from the typical background levels for White Island. This was accompanied by a steam explosion on Friday night which produced some volcanic ash. The volcanic tremor levels remained high until about 06:30 Monday March 30, then returning to background levels. However, since 10:15 the tremor levels have again increased to levels similar to those on the weekend.

The prevailing northerly-northeasterly conditions over the weekend were favourable for the plume to drift onshore Bay of Plenty. As a result numerous people have reported sulphur smells and some ash.

The current activity appears to be related to changes in the hydrothermal system. At present we have no indications of new magmatic activity. This will be confirmed once analysis of ash samples are made. The level and style of activity is presently insufficient to change the alert level.

We advise the Alert Level remains at Level 1.

Brad Scott
Volcano Surveillance Manager