Bay of Plenty residents may have spotted large steam and gas plumes coming from Whakaari/White Island in the past few weeks.
GNS Science volcano specialist Brad Scott said the steam and gas plumes originated from several active vents on the island and were clustered in and around the craters formed in December 2019.
Scott said several factors contributed to how the steam and gas plumes appeared above the volcano.
"These include heat flow, gas output, and the presence of groundwater, lakelets or crater lakes. Humidity, dew point, air temperature and windspeed can also play a role.
"Line all of these up like we did over the last couple of weeks and you can have large spectacular steam and gas plumes over the volcano."
Scott said gas was formed from subduction and magmatic processes at depth and was discharged at volcanoes and geothermal areas.
"The gas leaks from the rising geothermal fluids and molten rock (magma). Steam-water vapour (H2O) is the most common volcanic gas constituent.
"However, there are several other gas species present. After steam, in order of abundance they are carbon dioxide (CO2) sulphur dioxide (SO2) and hydrogen sulphide (H2S). GeoNet measures the amount of these present during regular gas flights."
What is the night glow?
A night glow has also been visible since June 30.
"Our volcanic cameras have both daylight and low-light cameras installed, allowing pictures to be taken at night when there is enough ambient light (such as from a full moon).
"The low-light cameras are also able to see the hot steam and gas vents, and these appear as a "glow" on our cameras on the island.
"This usually requires moderate-strong and hot emissions from the vents on the volcano for this to occur. Observations from a flight on 15 July confirmed temperatures of 500 to 600 degrees Celsius are now present."
The glow is only visible in the near infra-red with its webcam and unlikely to be visible with the naked eye.