The New Zealand volcanic eruption which killed at least five people was “not a total surprise”, according to a volcanologist.
White Island, east of the city of Bay of Plenty on New Zealand’s North Island, erupted on Monday about 2.10pm (local time).
New Zealand Police said people remain unaccounted for and of 23 people rescued five have died.
A number of Australians have been caught up in the eruption.
Dr Ken Gledhill, from the New Zealand geological agency GNS Science, told reporters the volcano "showed increased activity for the last few weeks".
"We can't be certain there won't be another eruption in the next 24 hours," Dr Gledhill said.
Brad Scott, a volcanologist with GNS Science, said the eruption was significant and sent a plume of steam and ash about 3,660 meters into the air. He said it had also affected the whole of the White Island crater floor.
GeoNet, which has been monitoring White Island, raised the alert level from one to two on November 18, noting an increase in the amount of sulfur dioxide gas, which originates from magma deep in the volcano.
It also said at the time that over the previous weeks, the volcanic tremor had increased from weak to moderate strength.
Mr Scott said the alert level was often raised and then later dropped again without any eruption.
He said there hadn’t been any major incidents with tourists visiting the island in the past, although there had been some close calls.
While he said it wasn’t for him to say whether tourists should have been visiting White Island before the eruption, Mr Scott said it’s not a surprise there was one.
“But as you are well aware, volcanic unrest has been occurring at White Island for several weeks now, so it's not a total surprise that this has led to a total eruption and we have alluded to this possibility for some time," Mr Scott told Stuff.
The GeoNet agency at first raised its alert level to four after the explosion, on a scale where five represents a major eruption. It later dropped the alert level back down to three.
Mr Scott said that was because the eruption wasn’t sustained beyond the initial blast.
Last Sunday, Mr Scott reported the Volcanic Alert Level at 2.
He noted “substantial gas, steam and mud bursts (were) observed at the vent located at the back of the crater lake”.
“The level of activity at the vent is variable and when in a stronger phase, some material is being deposited about the vent area,” he wrote.
“This style of activity has been present since late September, although it is occurring more frequently now. No volcanic ash is being produced.”
- With The Associated Press
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