Aug 7 2003, 2:00 pm - White Island Volcano

Over the last few months a substantial lake has formed in the active crater at White Island. This is the largest lake to have formed within this crater and has recently drowned the active vents. As a consequence future eruptions will occur through the crater lake and, if ejected by eruptions, moderate volumes of water could flood down the Main Crater floor towards the sea. This is a significant change in the nature of volcanic hazards on the island.

Over the last 10 - 15 years many small ponds and lakelets have formed in topographic lows or the floors of small sub-craters within the 1978/90 Crater Complex. Their life has often been short as they have been in filled by the next eruption, or drained as new vents have formed. The small volumes of these lakes, was such that they had no influence on eruptive activity. However, the current lake volume is large enough that it will influence the next phase of eruptive activity from the volcano and result in a new hazard to people visiting the island. Ejection of the lake in an eruption could cause flooding of the shallow stream valleys across the Main Crater floor, maybe as far as the sea. This would occur along with the already existing hazards caused by rock and ash fall during explosive eruptions.

Should there be no significant eruptive activity within the next 18 - 24 month period and the lake continues to fill, it may reach overflow level. In this situation water may overflow into drainage channels on Peg 12 Flat, to the south of 1978/90 Crater Complex and these channels may further erode if water is continuously flowing in them. It is our intention to establish a monitoring programme to accurately measure the level of the lake or its rate of rise.

There is no significant change in volcanic activity on the island, hence the Alert Level for White Island remains at Alert Level 1.

Brad Scott
Volcano Surveillance Co-ordinator