The volcanic alert level of Whakaari White Island has been lifted to level two this evening, after moderate unrest.
GNS Science said the volcano has historically high levels of sulphur dioxide - the second highest since regular measurements began in 2003.
Duty volcanologist Agnes Mazot said there have been clusters of earthquakes nearby recently, but the relationship between them and the high gas readings was unclear.
She said the change in gas readings was significant, and there was potential for an eruption.
White Island is about 50km from the mainland near Whakatane.
Whakaari/White Island is experiencing moderate volcanic unrest. The Volcanic Alert Level is raised to Level 2 and the Aviation Colour Code is raised to Yellow. Our recent monitoring of the volcano shows increased levels of volcanic gases. Read more here: https://t.co/GnyUuugwF4 pic.twitter.com/KE3PmRgIXu— GeoNet (@geonet) June 26, 2019