Deadly Volcanic Explosion Rocks New Zealand: Here’s Everything You Need To Know

A powerful volcanic eruption has rocked New Zealand’s White Island, a small uninhabited volcano sticking up out of the sea in the Bay of Plenty, 50 kilometres offshore of the country’s North Island.

Although details remain a little sparse, the New Zealand police force suspect that fewer than 50 people were present on the island when the eruption took them by surprise. At the time of writing, several people have been injured, some reportedly with serious burns, and some have been evacuated to the mainland. At least one person is critically injured.

A number of people on the island are currently unaccounted for. Police Deputy Commissioner John Tims told a press conference that at least one person has died, and that they are unlikely to be the sole casualty.

Plenty of news reports will focus on those injured by the eruption, and understandably so. Here, you’ll find some scientific information that should provide some background as to why this took place. As ever, I’ll update this as more information comes in, when I can.

So, what happened?

On Monday December 9th at 14:11pm in New Zealand’s time zone, (late at night on Sunday, Eastern Time), one took place on White Island, also known by its Māori name Whakaari. It has been described by GeoNet – an official scientific initiative that’s a collaboration between the New Zealand government’s Earthquake Commission and New Zealand-based geoscience institute GNS Science – as an impulsive, short-lived event that affected the crater floor. The activity, they say, appears to have diminished since the eruption.

The event generated an ash plume that rose 3,700 metres or so above the vent. As seen by webcam images, ash blanketed the crater floor, and ashfall seems to be more or less confined to the island.

                                   

So far, reports suggest that 20 people or so have been injured out of a possible 100 on the island at the time. Tourists can get boats or helicopters to the island, a near constantly restless volcano, to peer at its hyperactivity. It’s a small island, just 2,400 metres across at its longest, with its 321-metre-high summit simply the high point of the crater rim, which is open and exposed.

                                    

What kind of eruption was this?

It’s too early to tell, but the short time span of the main event, the fact that there have been injuries and the temporary ash plume that fell mostly back onto the island suggests that this was a type of volcanic explosion. It’s difficult to say what kind of blast it was at this stage, but it could either be one that unleashed fresh volcanic debris or one that didn’t, one that involved external water or one that didn’t.

Being so close to the sea, external water may have infiltrated White Island’s magma supply. When mixed in an appropriate manner and with the right magma-to-water ratio, you can get an explosive vaporization of the water which sets of a rapid chain reaction of violent depressurization events – i.e., an explosion. If this just releases steam and no new magmatic products, it is technically not an eruption, but a hydrothermal blast. If it does unleash novel volcanic debris, it is referred to as a phreatomagmatic eruption.

External water doesn’t necessarily have to be involved. Perhaps the blast was more like the one that recently took place at Italy’s Stromboli volcano, where a gloopy, gas-rich lump of magma high up the volcano’s throat (known as its conduit) managed to rush up to the surface via its own natural buoyancy, where the gas rapidly expanded and flung lava and ash into the sky. The Strombolian eruption style, named after the eponymous Sicilian volcanic isle, can be observed at volcanoes all over the world, but each eruption at each individual volcano can vary in intensity.

In any of these cases, people standing inadvertently too close to a powerful enough explosion can be harmed by all kinds of things, from the shockwave of the explosion itself causing damage to their internal organs to heavy, hot and sometimes molten debris being flung out by the blast.

                                  

The ash can also cause health hazards; it is toxic and glassy, so breathing it in can damage respiratory systems. The risk for harm is far greater for those with pre-existing breathing conditions than those who are otherwise healthy.

What kind of volcano is White Island?

It is the summit of a submarine volcano that is 16 by 18 kilometres across, one that erupted enough volcanic debris long ago to rise from the waves and prevent itself being reclaimed by them. According to the Smithsonian Institution’s Global Volcanism Program, it is made of two overlapping stratovolcanoes (steep, mountain-shaped volcanoes) that have a somewhat gloopy magmatic consistency – and, as a result, prone to trapping gas and causing explosive eruptions.

It is highly active, and its eruptions can sometimes produce topographic changes. In the 19th and 20th centuries, new vents have opened up, putting holes in the crater floor. Some of the crater wall catastrophically failed and collapsed in 1914, creating a debris avalanche that smothered buildings and workers at a sulphur mine.

What are its past eruptions like?

Māori legends have spoken of the eruptive fury of the volcano for some time now. Since 1826, observers have recorded a mixture of phreatomagmatic and strombolian eruption styles.

Most of the island’s eruptions rank as a 2 on the Volcanic Explosivity Index or VEI, which takes into account the amount of fresh volcanic debris ejected, the height of the ash plume, and some additional details. A 2 is classified as “explosive”, producing a 1-5-kilometre-high ash plume, and unleashes no more than 400 Olympic-sized swimming pools’ worth of fresh volcanic debris.

Sometimes, there have been eruptions ranking as a 3 on the VEI, which are described as “catastrophic”, producing a plume of ash up to 15 kilometres high and can make 4,000 Olympic-sized swimming pools’ worth of fresh volcanic debris. Each eruption, though, has its own characteristics and behaviours that the VEI doesn’t describe; the index is just used as a proxy for the explosivity and volume of debris involved in the eruption, with higher numbers being far less common around the world over time than the lower numbers.

In any event, this latest event certainly sounds like a 2 or 3 on the VEI. Even a 1 can injure or kill people; it depends where they were in relation to the eruption or blast when it took place.

Why wasn’t this eruption forecast?

For volcanoes that are well monitored, like White Island, scientists can look at an array of data – seismic signals that indicating magma cracking through rock as it rises, gas emissions at the surface that suggest magma is just below, the deformation of the ground as magma moves about, and so on – to forecast what may happen next in various timeframes. Although it is difficult to say with any certainty or precision when an eruption may happen and what kind of eruption it will be, for some volcanoes, volcanologists can get advanced notice that something may be about to happen. It could be an eruption, but it could also just be magma moving about and then going quiet.

Each volcano is idiosyncratic, though. They may all play by the same rules, but each player is different: some volcanoes are more hyperactive, others take a long time to erupt and spend most of their lifetime doing very little. There are many grey areas; Italy’s Stromboli volcano often coughs up some lava several times per day, and that is expected; every few years, though, it can engage in an explosive convulsion that sends debris shooting all over the place, just like it did earlier this year. Those rarer blasts are harder to predict, and often don’t give off any warning signs.

Similarly, 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.

What happens next?

There is a chance that this explosion may have helped unleash magma trapped beneath the surface, leading to a more prolonged eruption or perhaps a few more similarly sized explosions. It’s also possible that this was an isolated explosion, and the volcano was “clearing its throat” and nothing more. Only time will tell, but I’m sure for some time now tourists won’t be allowed near the island.

Is this related to the Ring of Fire or any other volcanic eruptions taking place right now?

Well, it is related to the Ring of Fire in that this volcano sits on it. This term described a conveniently shaped network of major tectonic boundaries that are continuously shifting around in very complex ways. Thanks to these behaviours, this network is responsible for 75 percent of the world’s volcanic activity, or thereabouts (and a staggering 90 percent of the planet’s earthquakes).

The underlying causes may be similar, but any eruptions that occur here happen independently of each other. There’s pretty much no evidence that volcanic eruptions can trigger other volcanic eruptions, (although there’s an ongoing healthy debate as to whether earthquakes, in some circumstances, can initiate volcanic eruptions nearby). What you are seeing here is just White Island doing its own thing.

On average, 40 volcanoes around the world are erupting at any one time. Sometimes, White Island is among them. This is par for the course, and not a sign of some sort of impending volcanological apoclaypse.

What can I do to help?

As always, don’t spread information whose veracity you are unsure of. Only used trusted, well-cited journalistic sources (hello!) or go to the official government or scientific networks, like GeoNet.

The spread of misinformation, accidental or intentional, will distract scientists and aid workers from their life-saving work, and it will sow erroneously founded seeds of panic in the minds of those affected by the disaster. If you see anyone doing this, politely but firmly tell them to stop; if they don’t, report them.

Follow me on Twitter.

Robin George Andrews is a doctor of experimental volcanology-turned-science journalist. He tends to write about the most extravagant of scientific tales, from eruptions

Source: Deadly Volcanic Explosion Rocks New Zealand: Here’s Everything You Need To Know

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Hawaii Volcano Quiets After Months-Long Eruption | Nathan Rott | NPR.org | Online Marketing Tools

After more than three months, the volcanic eruption on Hawaii’s Big Island appears to be slowing.

Geologists at the Hawaiian Volcanic Observatory say the flow of lava from a crack in the earth at the foot of the Kilauea volcano has greatly diminished in recent days.

It was lava from that vent, Fissure 8, that ran toward the coast in a molten river, inundating two seaside communities and reshaping the island’s southeast coast.

That doesn’t mean the event is over. Tina Neal, the scientist in charge of the observatory, noted that eruptions like this typically wax and wane.”It could be weeks or months before we feel comfortable calling the eruption and the summit collapse over,” she said in a press release.

Source: Hawaii Volcano Quiets After Months-Long Eruption | Nathan Rott | NPR.org | Online Marketing Tools

 

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