Whakaari/White Island could be entering a “new eruptive episode”, volcanologists say.
In a volcanic activity bulletin released on Monday, GNS Science duty volcanologist Agnes Mazot said the volcano had been seen producing larger steam and gas plumes and the occasional “passive” emission of volcanic ash.
“The volcano is not actively erupting but the current activity could be leading to a new eruptive episode.”
The Aviation Colour Code has been raised to orange while the Volcanic Alert Level remained at 2.
Orange indicates that the volcano is “exhibiting heightened unrest with increased likelihood of eruption”. Alert Level 2 indicates volcanic unrest hazards and the potential for eruption hazards.
Emissions from the active vent changed during a routine gas measurement flight on December 14 to include more volcanic ash than when measurement began an hour earlier, Mazot said.
“The results from the gas flight along with satellite observations, show a general increase in sulphur-dioxide (SO2) and carbon dioxide (CO2) emissions from the volcano. These are taken together to indicate a new eruptive episode may be starting.”
On December 10, a larger steam and gas plume was visible above the island — evident on GNS webcams at Whakatāne and Te Kaha as well as on satellite imagery.
Mazot said a larger plume can sometimes be seen from the Bay of Plenty coast when weather allows.
“The observations during the gas flight are the only signs of volcanic ash in the plume to date. Ash emission has not been visually noted from our webcams, or via MetService’s analyses of satellite imagery.”
Without sensors, remote cameras and satellite imagery remain the only way to monitor the island.
“The changes in activity and what we observed from May to September suggest fresh magma is driving a change in activity,” Mazot said.
She added that the alert levels acknowledge the current level of activity but also reflect the degree of uncertainty about the level of unrest due to the current lack of consistent, usable real-time monitoring data.
“The level of volcanic activity could escalate back to levels seen earlier in the year and the volcano can erupt with little or no warning.”
