Whakaari is New Zealand’s most active cone volcano and displayed signs of increased activity as recently as last week.
An expert has warned New Zealand’s Whakaari Island was “a disaster waiting to happen for many years”, just hours after at least five people were killed on by a volcano eruption on the popular tourist spot.
New Zealand authorities have confirmed the deaths of five people after the eruption of the Whakaari volcano on Monday.
A report from New Zealand geological monitor GeoNet said the eruption generated an ash plume climbing around 3,600m above the vent.
But Monash University School of Earth, Atmosphere and Environment’s Emeritus Professor Ray Cas said he always felt it was too dangerous a spot for tourism.
“White Island has been a disaster waiting to happen for many years. Having visited it twice, I have always felt that it was too dangerous to allow the daily tour groups that visit the uninhabited island volcano by boat and helicopter,” he said.
“It has a very active geothermal system with many steaming gas vents and varying numbers of hot water filled crater lakes in the floor of an amphitheater-shaped large crater.”
If volcanic eruptions are common on Whakaari, why can tourists go there?
Whakaari is New Zealand’s most active cone volcano and displayed signs of increased activity as recently as last week, according to GeoNet.
The site, also known as White Island, sat at a Volcanic Alert Level of 2 and was “regularly throwing mud and debris 20-30 metres into the air”, the monitor said in a notification on 3 December.
“Observations and data to date suggest that the volcano may be entering a period where the eruptive activity is more likely than normal,” it said.
Associate Professor Derek Wyman, a geoscientist at Sydney University, said he was surprised tourists were allowed so close to the site, given its recent history.
"I certainly wouldn’t be recommending tourists be approaching a site that has recently been throwing material up 30 metres into the air," he said.
The eruption, on the scale of things, was "a relatively minor event", Professor Wyman said.
"New Zealand sees things like this quite frequently,” he said.
“Usually people don’t die from these kinds of eruptions, but that is likely because they are not usually inappropriately close."
Ross Dowling, an honorary professor of Tourism at Edith Cowan University, said an increasing number of people were visiting active volcanoes.
“Part of the attraction is to visit an unpredictable natural environment and for most tourists, they assume that they will be able to visit such dangerous sites in relative safety,” he said.
He said hazard management guidelines need to be easily understood by people travelling to volcanic sites.
“One such strategy is to simply allow visitors to view active volcanoes from a distance and not allow them on to any volcano deemed still in its active phase, he said.
“In this way, risks to the public will be reduced, whilst still allowing adventurous visitors a chance to see and experience those elements of the landscape which are active and dramatic."
How do eruptions happen?
University of Auckland volcanologist Shane Cronin said unexpected eruptions from volcanoes such as that on White Island can be “expected at any time”.
“Magma is close to the surface, and the heat and gases from this heat the surface and ground waters to form vigorous hydrothermal systems,” Professor Cronin said.
“Hydrothermal [eruptions] can occur suddenly and with little or no warning because they are driven by the expansion of super-heated water into steam.
"The hazards expected from such events are the violent ejection of hot blocks and ash, and formation of 'hurricane-like' currents of wet ash and coarse particles that radiate from the explosion vent.
“These can be deadly in terms of causing impact trauma, burns and respiratory problems.”
Could more eruptions come in the next few days?
Professor Cronin said eruptions were generally short-lived, but once one occurs; there is an increased risk of further, smaller ones as the system re-equilibrates.
While the Volcanic Alert Level has been revised down to Level 3, Professor Wyman said, there is “nothing to suggest something like this will not happen again soon”.
“It appears the crisis of the day is over, but that is not to say it could not happen again next week,” he said.
Chris Elders, a professor of Geology at Curtin University, said it was "difficult to predict” whether Whakaari will experience sustained heightened levels of volcanic activity as a result of Monday’s eruption.
But, he said, the eruption is unlikely to stimulate volcanic activity in other parts of the region.
“Volcanic eruptions depend on the state of individual volcanoes. They do not really affect one another.”