Whakaari/White Island is now erupting a continuous stream of volcanic ash – prompting an alert level raised to 3 and a warning that more violent explosions could strike suddenly.
Earth Sciences NZ confirmed the change after an observation flight over the volcanic island on Tuesday afternoon.
The flight showed activity had shifted from intermittent bursts to a steady, low-energy eruption of steam, gas and ash.
The Volcanic Alert Level rose from 2 to 3, signalling a minor volcanic eruption. The Aviation Colour Code moved from yellow to orange.
Earth Sciences New Zealand duty volcanologist Michael Rosenberg said a blanket of ash could be seen around the active vent in the Main Crater.
“A small amount was being carried upwards in a column of steam and gas. The discharge was weak, with no evidence that any explosive eruption had occurred.”
Vent temperatures quadruple, sulphur smell possible
The temperature of the gas coming out of the vent had climbed from about 100C to about 395C in a week, he said. Satellites had also picked up sulphur dioxide from the volcano every day.
Ash had built up close to the vent and spread thinly across the crater floor and the island’s outer slopes. The vent itself had not changed in size or shape since scientists last saw it on October 12.
Rosenberg said the mainland faced no threat beyond a possible sulphur smell and light ash fall.
“There have been no reports of ash affecting the mainland, but people might smell sulphur gases during onshore winds and potentially notice some ash particles.”
Conditions on and around the island could change fast, however.
“While the current ash emission is quite passive and low energy, volcanic activity could escalate with little or no warning,” Rosenberg said.
“Sudden, more explosive events can throw rocks across the Main Crater floor and produce ash and gas surges (pyroclastic flows), both of which can be a threat to life on the Main Crater floor and area immediately offshore on the SE of the island.”
Whakaari sits about 48km off the coast from Whakatāne in the Bay of Plenty. Its eruption on December 9, 2019 killed 22 people, most of them tourists who visiting the island.
Rosenberg said the latest activity was typical of the volcano’s eruptive cycles. with past episodes over the last 30 years suggesting it could continue for weeks.
Scientists’ ability to watch the volcano in near real time remained limited because the island had no working monitoring instruments.
Earth Sciences NZ's Volcano Monitoring Group and the National Geohazards Monitoring Centre relied on observations from the mainland, satellite data and occasional flights near the island, with extra information from MetService.
MetService’s Volcanic Ash Advisory Centre will continue to assess any impact on aviation.
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