The aviation colour code system is based on four colours and is only intended for use by the civil aviation community.
The levels are green – normal, non-eruptive state; yellow – signs of unrest; orange – heightened unrest with increased likelihood of eruption, or volcanic eruption is under way with no or minor ash emission. And finally – red – where eruption is forecasted to be imminent with significant emission of ash into the atmosphere likely, or eruption is under way with significant emission of ash.
“During a routine gas measurement flight on December 14, the emissions from the active vent changed and include more volcanic ash than when measurement started an hour earlier,” said Mazot.
“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.”
Mazot said these taken together indicated a new eruptive episode may be starting.
“During the gas measurement flight on 14 December, we observed minor volcanic ash emissions and an increase in gas emission rates,” Mazot said.
On December 10, a larger steam and gas plume was also visible above Whakaari, evident on GNS webcams at Whakatāne and Te Kaha as well as on satellite imagery.
Mazot said when the weather allowed, a larger plume could sometimes be seen from the Bay of Plenty coast above the island.
“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.”
Mazot said without sensors on the island, scientists continued to rely on remote cameras and satellite imagery to monitor Whakaari.
“The changes in activity and what we observed from May to September suggest fresh magma is driving a change in activity. To date only very minor ash emissions have been noted near and on the island.
“We are planning an observation flight to make more observations and monitor potential changes in the crater area.”
A photo taken during the gas measurement flight on December 14 showed the volcanic ash emission from the active vent and the gas and steam plume drifting downwind.
Recent activity was consistent with moderate-to-heightened unrest.
Mazot said the alert levels acknowledged the current level of activity but also reflected the degree of uncertainty about the level of unrest due to the 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.
GNS Science’s volcano monitoring group and national geohazards monitoring centre would continue to closely monitor Whakaari/White Island for any changes in activity.
“We will provide further updates when information becomes available,” Mazot said.
For information about the impacts of the steam and gas plume should it reach the coast, GNS advised following the advice from:
- SunLive
