The Whakaari, or White Island, volcano, 48 kilometres (30 miles) away from the Bay of Plenty, on the north island’s east coast, began erupting at around 2.15pm local time, sending a plume of ash and debris 3,657 metres above the mainland. New Zealand authorities say 20 people are still missing, and five people have lost their lives as a result of the blast. However, what caused the eruption is still a mystery, with experts confirming there was little to no warning.
One geologist said the eruption was “basically instantaneous”, and it should be a warning that natural disasters can strike at any moment.
Brad Scott of GNS Science, a geographical monitoring service in New Zealand, told the NZ Herald: “One minute nothing’s happening, next minute, it’s all happening.”
One possible reason for the sudden and unexpected blast is that external water may have infiltrated the volcano.
With the White Island being located in the ocean, and the volcano’s vent situated below sea level, there is every chance water made its way in where, if the water-magma ratio is just right, it can cause a drastic buildup of steam which has to exit somewhere.
University of Auckland volcanologist Shane Cronin said: “Magma is close to the surface, and the heat and gases from this heat mean the surface and ground waters are likely to form vigorous hydrothermal systems,” he said.
“We know hydrothermal and so-called phreatic eruptions can occur suddenly and with little or no warning because they are driven by the expansion of super-heated water into steam.”
Robin Andrews, a a doctor of experimental volcanology-turned-science journalist, wrote for Forbes: “The explosion at White Island was fairly spontaneous; a violent sneeze if you will, one that wouldn’t have given New Zealand’s scientific instrumentation any warning signs until the moment it took place, or perhaps immediately before.
“The volcano had been rumbling a little more than its background level over the past few weeks, so the authorities had raised the alert level a little, but there was no way they could have foreseen this sort of paroxysm.
“There was little anyone could have done, I suspect – this was just bad luck on the part of those tourists.”
New Zealand’s Prime Minister Jacinda Ardern told the media: “Police were alerted at 2.17pm.
“At this stage, and please do keep in mind this is an evolving situation, we believe around 100 people were on or around the island at the time and some of those are at this stage unaccounted for.
“I want to share this is evolving at this stage, at this stage it does appear to be a very significant issue, particularly the scale of those affected.”