Volcanic activity at White Island has increased.

GeoNet duty volcanologist Steve Sherburn says a report from the island at 11.50am confirmed increased ash emission.

The volcano's Crater Lake is reforming. This photo was taken during a visit on September 6. Photos: GeoNet.

The Volcanic Alert Level is now raised to Level 3, from Level 1minor volcanic ash been passively emitted from a vent on the 2012 lava dome.

Steve says ash has been passivelly emitted from White Island since 2012.

The Aviation Colour Code is changed from Green to Orange.

"The current activity is minor. We are unsure of the implications for visitor safety and will be issuing a further VAB later this afternoon."

Observations during a visit last week confirmed the Crater Lake is reforming and growing.

Scientist are reporting increased activity at White Island this morning. Photo: GeoNet.

The April 27 eruption removed about 13-15 m of lake floor sediments and the new lake is forming at a lower level on the floor of the crater, says volcanoloigist Brad Scott.

The lake is currently about 28.4 m below the overflow level.

Since May 19, the water level has risen about 3m and the lake temperature has decreased as it gets larger.

The temperature is now 52 ºC. The lake is now a light lime green colour, having changed from a milky grey shortly after the April eruption.

Sulphur tower growing near Fumarole 0.

"We are sometimes able to get Thermal IR images of a rocky lava mound in the back of the 1978/90 Crater and have established information on the very high temperatures that are present there.

"This is the same area where a lava dome grew in 2012. There are two areas of hot gas output and the temperature measurements ranged from 198 to 295 ºC.

"These are down on the measurements we made in August when they ranged 292 to 337 ºC in the hottest area. The temperature of Fumarole 0 (the largest accessible one) has changed little. We measured 170-173 ºC this time and 168-171 ºC last visit.

"As we reported in May and June many of our survey pegs were sheared off or broken by the April eruption," says Brad.

"This has had implications for the regular surveys we do like the levelling, magnetics and soil gas flux. We have completed reinstalling pegs and made the first magnetic and levelling surveys last week. Minor volcanic unrest continues."

GNS staff making magnetic measurements.

Thermal IR image; Sp1 = 295 C, Sp2 = 198 C.