White Island's crater lake continues to grow, which could lead to small hydrothermal eruptions, according to GeoNet.
The Volcanic Alert Level remains at one, but volcanologist Brad Scott said the rising water was encroaching on the larger and hotter gas vents on the 2012 lava dome and would soon start to drown them.
Hydrothermal activity on the surface would change as the vents drown, which could include localised steam-driven activity such as geysering and small hydrothermal eruptions, Scott said.
"It is difficult to quantify the style of activity that will occur as the vents are drowned," Scott said.
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In April and May this year visitors to the island heard loud sounds from the active crater area.
These have now stopped as the geothermal system adjusted to the new lake.
Scott said if the lake continued to fill at the current rate features on the side of the dome would be drowned early to mid-August and the dome would be totally drowned in three to four months.
"The lake is now 17m below overflow and is filling at about 2000 m3 per day. This is essentially the same rate as seen in 2003-4, 2007-8 and 2013."
A recent visit to the island confirmed volcanic activity remained steady at a low level. Scott said the minor unrest does not change alert levels at the island.
"Crater lakes have formed in the past and we do see changes in the geothermal activity associated with this - but no signs of increased volcanic unrest." GNS Science continues to closely monitor White Island and our other active volcanoes.