The volcanic alert level at Whakaari/White Island has been raised due to a lack of real-time monitoring and increased uncertainty at the volcano.
GNS Science reported last month real-time monitoring on Whakaari/White Island had been lost as instruments on the volcano had not been serviced since the December 2019 eruption.
Power supplies, sensors and cameras had degraded or failed over time.
GNS Science raised the alert level at the volcano to Volcanic Alert Level 2 today as it was now effectively unable to distinguish in near real-time between level 1 (minor volcanic unrest) and level 2 (moderate to heightened unrest) in between monitoring flights.
The rise in alert level was not due to a noticed increase in volcanic activity but to "acknowledge the greater level of uncertainty in our interpretation due to the current lack of real-time data", GNS Science said.
"We feel this prudent approach more accurately reflects the level of uncertainty about what might be happening undetected at Whakaari/White Island because we do not have this critical real-time data.
"Until we are able to service our on-island equipment and power supplies, we will be increasing the frequency of our gas and observation flights to the island.
"We also still have intermittent access to webcam images from the island, providing some level of visual monitoring between our flights."
GNS Science said it strongly relied on real-time data collected by permanent instrumentation on volcanoes across New Zealand, in addition to regular observation flights and airborne gas measurements.
"Our most recent observation flight indicates the level of activity at the island had remained low, with normal fumarole and gas emissions.
"Atmospheric conditions have produced tall steam and gas plumes above the
island in the morning some days, sometimes visible from the coast."
The Aviation Colour Code has also changed to yellow at the island.