• Written by Shane Cronin, Professor of Earth Sciences, University of Auckland
The sudden eruption at White Island was short-lived but produced an ash plume that rose several kilometres above the vent. GNZ Science, CC BY-ND

Five people have been confirmed dead, 31 remain in hospital with injuries and eight are still missing after sudden volcanic eruptions on Whakaari/White Island off the east coast of New Zealand.

The island is a tourist destination and 47 people were on it when it erupted on Monday afternoon. Three of those rescued have now been discharged from hospital.

Volcanologists at GeoNet, which operates a geological hazard monitoring system, described the eruption as impulsive and short-lived, with an ash plume that rose to more than three kilometres above the vent.

Prime Minister Jacinda Ardern this morning praised the courage of the first responders and pilots who conducted an aerial survey. She confirmed that the flyovers have shown no signs of life. Police are today assessing whether it is safe to return to the island for a recovery operation.

This footage was taken by Michael Schade whose family got off Whakaari/White Island 20 minutes before it erupted.

Volcanic hazards

White Island is one of several volcanoes in New Zealand that can produce sudden explosive eruptions at any time. In this case, magma is shallow, and the heat and gases affect surface and ground water to form vigorous hydrothermal systems.

In these, water is trapped in pores of rocks in a super-heated state. Any external process, such as an earthquake, gas input from below, or even a change in the lake water level can tip this delicate balance and release the pressure on the hot and trapped water.

The resulting steam-driven eruption, also called a hydrothermal or phreatic eruption, can happen suddenly and with little to no warning. The expansion of water into steam is supersonic in speed and the liquid can expand to 1,700 times its original volume. This produces catastrophic impacts.

The expansion energy is enough to shatter solid rock, excavate craters and eject rock fragments and ash out to hundreds of metres away from the vent. We know of sites in New Zealand where material has been blasted out over three kilometres from the vent by such eruptions.

The eruption on White Island sent sent huge amounts of steam and ash into the air in the blast. GeoNet, CC BY-ND

Potential for further eruptions

The hazards expected from steam-driven eruptions are violent ejections of hot blocks and ash, and the formation of “hurricane-like” currents of wet ash and coarse particles that radiate from the explosion vent. These can be deadly in terms of impact trauma, burns and respiratory injuries.

The eruptions are short-lived, but once one happens, there is a high chance for further, generally smaller ones as the system re-equilibrates. White Island is an acute location for such activity, but it is not the only location in New Zealand where this can happen.

Mount Ruapehu (crater lake), Mount Tongariro (Te Maari and Ketetahi) and geothermal areas of the central North Island all have the potential to cause such events. We know there have been more than 60 hydrothermal eruptions in the last 100 years in New Zealand. Some of these have caused loss of life.


Read more: Each volcano has unique warning signs that eruption is imminent


No warning

Monitoring and warning for hydrothermal eruptions is a huge challenge. We don’t normally see these eruptions coming, no matter how much we would like to. Many systems are already “primed” for such events, but the triggers are poorly understood.

The warning periods, once an event gets underway, are likely in the order of seconds to minutes. Our only hope for anticipating these events is to track potential vapour and liquid pressure in hydrothermal systems and to learn from their long-term behaviour when they are at a super-critical state. Unfortunately there are no simple rules that can be followed and each hydrothermal system is different.

In this age of technology and instrumental monitoring, it seems irrational that there should be little or no warning for such eruptions. The eruption is not caused by magma, but by steam, and this is much harder to track in our current monitoring systems.


Read more: Why Japan’s deadly Ontake eruption could not be predicted


We have seen several other fatal hydrothermal catastrophies unfold in other parts of the world, such as the 2014 eruption of Mount Ontake in Japan. New Zealand has been luckier than many other parts of the world, until now.

Shane Cronin does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Authors: Shane Cronin, Professor of Earth Sciences, University of Auckland

Read more http://theconversation.com/why-white-island-erupted-and-why-there-was-no-warning-128550

All You Need to Know About Trenchless Technology

For many years, the traditional sewerage lines and pipe developments were not enough due to the long wait and cracking. The traditional sewer pipe repairs involved cracking the earth to find the par...

News Company - avatar News Company

Before we rush to rebuild after fires, we need to think about where and how

A primary school in East Gippsland was burnt down in the current bushfire crisis. While Premier Daniel Andrews immediately committed to rebuilding the school as it was, media reported the local CFA ca...

Mark Maund, PhD Candidate, School of Architecture and Built Environment, University of Newcastle - avatar Mark Maund, PhD Candidate, School of Architecture and Built Environment, University of Newcastle

Australian sea lions are declining. Using drones to check their health can help us understand why

Australian sea lions (Neophoca cinerea) are one of the rarest pinnipeds in the world and they are declining. Jarrod Hodgson, CC BY-NDAustralian sea lions are in trouble. Their population has never rec...

Jarrod Hodgson, PhD Candidate, University of Adelaide - avatar Jarrod Hodgson, PhD Candidate, University of Adelaide

With costs approaching $100 billion, the fires are Australia's costliest natural disaster

It’s hard to estimate the eventual economic cost of Australia’s 2019-20 megafires, partly because they are still underway, and partly because it is hard to know the cost to attribute to de...

Paul Read, Climate Criminologist & Senior Instructor/Lecturer, Faculty of Medicine, Monash University - avatar Paul Read, Climate Criminologist & Senior Instructor/Lecturer, Faculty of Medicine, Monash University

In cases of cardiac arrest, time is everything. Community responders can save lives

Cardiac arrest can occur with little or no warning in people who were previously healthy, including young people. From shutterstock.comEach year more than 24,000 Australians experience a sudden cardia...

Bill Lord, Adjunct Associate Professor, Monash University - avatar Bill Lord, Adjunct Associate Professor, Monash University

So the government gave sports grants to marginal seats. What happens now?

When Australians pay their income tax, they assume the money is going to areas of the community that need it, rather than being used by the government to shore up votes for the next election. This is...

Maria O'Sullivan, Senior Lecturer, Faculty of Law, and Deputy Director, Castan Centre for Human Rights Law, Monash University - avatar Maria O'Sullivan, Senior Lecturer, Faculty of Law, and Deputy Director, Castan Centre for Human Rights Law, Monash University

The Olympics have always been a platform for protest. Banning hand gestures and kneeling ignores their history

It is the year of the Tokyo Olympics, and the International Olympic Committee was quickly out of the blocks with new guidelines regarding athlete protests. The IOC is worried the biggest stories of...

David Rowe, Emeritus Professor of Cultural Research, Institute for Culture and Society, Western Sydney University - avatar David Rowe, Emeritus Professor of Cultural Research, Institute for Culture and Society, Western Sydney University

Where Can You Get Weed By Ordering It Online?

Nowadays, everyone wants to get their hands on some weed. Marijuana has become legalized in a lot of countries worldwide. People wait in lines for days to buy some. You couldn’t have imagined that...

News Company - avatar News Company

Hidden women of history: Catherine Hay Thomson, the Australian undercover journalist who went inside asylums and hospitals

Catherine Hay Thomson went undercover as an assistant nurse for her series on conditions at Melbourne Hospital. A. J. Campbell Collection/National Library of AustraliaIn this series, we look at under...

Kerrie Davies, Lecturer, School of the Arts & Media, UNSW - avatar Kerrie Davies, Lecturer, School of the Arts & Media, UNSW

Sick and Tired of Your Dead End Job? Try Teaching!

Tired of the same old grind at the office? Want an opportunity to impact lives both in your community and around the world? Do you love to travel and have new experiences? Teaching English is the perfect job for you! All you need is a willingness to ...

News Company - avatar News Company

The Impact of an Aging Population in Australia

There’s an issue on the horizon that Australia needs to prepare for. The portion of elderly citizens that make up the country’s overall population is increasing, and we might not have the infrastructure in place to support this. Australians h...

News Company - avatar News Company