Alert level raised for White Island volcano

White Island. File photo / Alan Gibson

A volcano off the coast of Whakatane continues to show signs of increased activity, with scientists raising the alert level from Level one to Level two.

GNS Science has raised the alert level after monitoring of the White Island web camera captured a small eruption on Sunday morning from the Crater Lake. During the past week there has been an increase in volcanic tremor and volcanic gas levels.

The aviation colour code for White Island, the country's most active volcano, was lifted from green to yellow by GNS Science last month to alert pilots flying over the Bay of Plenty region.

Today it was changed to Orange.

"These phenomena are not unknown for White Island, but this is the first substantial confirmation that small scale eruptions are now occurring on the island and confirms the risk to visitors has increased,'' said a statement from the Bay of Plenty Civil Defence Group.

"White Island is an active volcano and there is always risk when visiting the island and vessels travelling nearby should keep alert.

"Eruptions can occur at any time with little or no warning. Extra caution should be taken if visiting the island.''

Overnight Friday 27 to Saturday 28 July the lake level in the Crater Lake at White Island rose by about three metres to 5m. A volcanic earthquake was also recorded indicating an eruption may have occurred.

Since then, a flow of gas and steam has been present through the lake, and from vents near the lake. A gas flight on August 1 recorded increases of sulphur gases in the steam and volcanic gas plume.

Since early July there have been intermittent periods of volcanic tremor, becoming more continuous since July 28. A particularly strong episode was recorded overnight August 4-5, and ended in a volcanic earthquake at 4.54am.

Examination of the images from the Factory webcam between 4.54am and 4.57am on 4 August revealed an eruption from the Crater Lake.

GNS Science volcanologists are monitoring the activity and further information would be released as soon as it is available.

"We haven't seen anything like this for the last couple of years and that increases the likelihood that something is going to be expelled from the volcano that might impact on aviation traffic,'' duty volcanologist Michael Rosenberg said earlier today.

Volcanologists visit the island every three months, and seismic signals are monitored continuously.

White Island last erupted in 2000.