Romanian volcano potentially onnly dormant!

[deaddirty]

Meatpie - something to keep you awake at night.

Magma found simmering under an 'extinct' volcano. Here's what that means.



Lush rolling hills cradle the still waters of Romania’s Saint Anne Lake, which rests in an ancient crater from the eruption of the Ciomadul volcano. The peak last blew its top some 30,000 years ago, and its lengthy quiescence has led many to presume the volcano would not likely erupt again.
But as it turns out, the rocks miles below this serene scene may be stewing with a surprising amount of heat. A study recently published in Earth and Planetary Science Letters suggests that the system likely harbors between five and 14 cubic miles of magma, a maximum volume more than that of 20,000 Great Pyramids of Giza.
To be clear, this does not mean an eruption is necessarily in the volcano’s future. But the work calls attention to the potential hazards of often overlooked volcanoes that have quietly simmered for tens of thousands of years.
“We look preferentially at active volcanoes—obviously because they show evidence of real risk,” says study author Mickael Laumonier of Université Clermont Auvergne, France. “But we shouldn’t forget other relatively recent young volcanoes, because they could present a risk that we should assess.”


By pairing geophysical and geochemical analysis with numerical simulations, the study gives researchers a stunning peek into what may be brewing beneath Ciomandul—and it promises to help scientists better understand how similar volcanic systems evolve over time.
“All of this is great work,” says Janine Krippner, a volcanologist at the Smithsonian Global Volcanism Program who was not involved in the study. But she cautions that teasing apart the precise conditions miles beneath the surface is an incredibly difficult task.
“It’s still not us saying that’s what the case is,” she says. “It’s saying, We have a lot of data that show this is what it might be.”
Eternal volcanic flames
At any given time, at least 20 volcanoes are erupting around the world. But there are many more that can potentially be active—the problem is figuring out which ones.
Volcanoes like Ciomadul that haven’t erupted in the last 10,000 years or so are often called inactive. However, this dividing line is somewhat arbitrary, Krippner says.
When it comes to volcanoes, “‘extinct’ is a very iffy word,” she says. Some volcanoes, like the infamous Yellowstone supervolcano, may lie dormant for hundreds of thousands of years between eruptions.
One sign that a seemingly quiet volcano has the potential for future eruptions is if volumes of molten rock linger below it, and past studies at Ciomadul had hinted that might be the case. By studying the way seismic waves ricochet through the ground, past researchers spotted some indications of a magma reservoir. Surveys of the subsurface electrical conductivity—a property that is influenced by conditions like the temperature and water content of the rocks—also hinted that the zone between three and 17 miles down may be more mush than solid.
Yet it was still unclear if the rock was truly molten, and if so, how much magma there might be.
Consulting crystal record-keepers
To answer these questions, Laumonier and his colleagues first turned to rocks from the volcano’s past eruptions. As magma sits beneath a volcano, it slowly cools and forms crystals, some of which act as tiny mineralogical record-keepers, charting the conditions in which they formed.
For example, a class of minerals known as amphiboles change chemistry depending on the temperature and pressure during crystallization. Searching for these crystals in the erupted rock helps researchers learn about the conditions of this ancient magmatic system.
The team combined this geochemical data with what they knew of the system’s dimensions and ran numerical simulations to determine how quickly it might have cooled through time, and to see what the volcanic plumbing could look like today. The result: The rocks in the upper crust beneath the volcano are, on average, 15 percent molten, with some regions as high as 45 percent.
The team verified this result by crafting a model based on measurements of electrical conductivity for previously erupted rocks at varying temperatures, pressures, and water content. This helped them interpret what was seen before in the electrical conductivity measurements under Ciomadul.
This second approach gave a similar result, suggesting that the zone beneath the volcano is indeed between 20 and 58 percent molten. While this is a large range for the amount of magma that could be lingering in Ciomadul’s subsurface pipes, all the possible subsurface conditions yield a significant amount of melt for Ciomadul.
“We have no other options to explain the geophysical anomaly,” Laumonier says.
Researchers believe that an eruption is possible if a volcano harbors more than roughly 45 percent molten rock. Below that, the “system is all locked up by crystals, and it can’t erupt,” says Michael Ackerson, curator of rocks and ores at the Smithsonian National Museum of Natural History in Washington, D.C.
Thus, this latest analysis suggests that an eruption may be possible at Ciomadul—but that does not mean it’s inevitable.
Mushy plumbing
Importantly, this study also probes the question of what such systems deep inside Earth actually look like.
“The traditional trope of a magma chamber is this big, gigantic menacing-looking, red-hot blob of magma sitting in the crust that’s about to erupt and kill us all,” Ackerson says.
But research increasingly suggests that’s likely not the case. Instead, magma reservoirs spend most of their lives quietly stewing in the crust. They’re often at least in part crystallized, forming a mushy, stony soup with varying proportions of crystals to melt throughout the system. This ratio might drastically differ in the magmatic plumbing of one volcano to the next.
For Ciomadul, the researchers believe the molten rock collects in two zones of mush: an upper region between three and 11 miles deep and a lower, hotter reservoir starting around 18.5 miles down. Each of these zones is likely composed of overlapping pockets of molten material of slightly different temperature and composition. For now, it’s unclear how the two zones precisely connect, but the new magmatic mapping still provides valuable information about this volcano’s inner workings.
“This is a new data point in the story of global magmas,” Ackerson says. “This is one specific volcano in one specific point in time, and that’s going to help us get a much broader, nuanced picture of how magmas form and evolve.”

http://www.msn.com/en-gb/news/world...at-means/ar-AAEzTT0?li=BBoPWjQ&ocid=DELLDHP17

 

[Meatpie]

Thanks very interesting this volcano is too far north to have any impact on life in Bulgaria.

 

[deaddirty]

Thanks Meatpie - though don't count on it, according to the Wikipedia entry tephra probably from the last eruption of Ciomadul reached as far as Odessa, so on a NE wind Sofia would be well within range of an ashfall. But even if it really is dormant rather than extinct, the likelihood of an eruption within our lifetimes must be very low.
Some further sources, from a quick Googling:
https://en.wikipedia.org/wiki/Ciomadul
https://www.researchgate.net/figure...-north-only-volcanic-domes-and_fig4_298470829
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GC008153

 

[Meatpie]

Thanks DD. Iceland volcanoes are much more active and dangerous for the whole of Europe currently there are 30 active volcanic systems there. Over the past 500 years, Iceland's volcanoes have erupted a third of the total global lava output.

 

[deaddirty]

Thanks Meatpie. Icelandic volcanoes probably aren't much danger to the rest of Europe except by disruption to air travel from high-level ash clouds - the lava is free-flowing so gas can escape easily and that type of volcano rarely produces caldera collapses or other major explosions.
Actually I take that back to an extent. The 1783-4 eruption of Laki and nearby fissures released huge amounts of sulphur dioxide and an unusually persistent high pressure system with dry NW winds meant that crops, animals and people were killed over much of Europe. From the Wikipedia entry:

"Consequences in Europe[edit]
An estimated 120,000,000 long tons (120,000,000 t) of sulfur dioxide was emitted, about three times the total annual European industrial output in 2006 (but delivered to higher altitudes, hence more persistent), and equivalent to six times the total 1991 Mount Pinatubo eruption.[13][19] This outpouring of sulfur dioxide during unusual weather conditions caused a thick haze to spread across western Europe, resulting in many thousands of deaths throughout the remainder of 1783 and the winter of 1784.
The summer of 1783 was the hottest on record and a rare high-pressure zone over Iceland caused the winds to blow to the south-east.[13] The poisonous cloud drifted to Bergen in Denmark–Norway, then spread to Prague in the Kingdom of Bohemia (now the Czech Republic) by 17 June, Berlin by 18 June, Paris by 20 June, Le Havre by 22 June, and Great Britain by 23 June. The fog was so thick that boats stayed in port, unable to navigate, and the sun was described as "blood coloured".[13]
Inhaling sulfur dioxide gas causes victims to choke as their internal soft tissue swells – the gas reacts with the moisture in lungs and produces sulfurous acid.[20] The local death rate in Chartres was up by 5% during August and September, with more than 40 dead. In Great Britain, the east of England was most affected. The records show that the additional deaths were among outdoor workers; the death rate in Bedfordshire, Lincolnshire and the east coast was perhaps two or three times the normal rate. It has been estimated that 23,000 British people died from the poisoning.[21]
The weather became very hot, causing severe thunderstorms with large hailstones that were reported to have killed cattle,[22] until the haze dissipated in the autumn. The winter of 1783–1784 was very severe;[23] the naturalist Gilbert White in Selborne, Hampshire, reported 28 days of continuous frost. The extreme winter is estimated to have caused 8,000 additional deaths in the UK. During the spring thaw, Germany and Central Europe reported severe flood damage.[13]
The meteorological impact of Laki continued, contributing significantly to several years of extreme weather in Europe. In France, the sequence of extreme weather events included a surplus harvest in 1785 that caused poverty for rural workers, as well as droughts, bad winters and summers. These events contributed significantly to an increase in poverty and famine that may have contributed to the French Revolution in 1789.[24] Laki was only one factor in a decade of climatic disruption, as Grímsvötn was erupting from 1783 to 1785, and there may have been an unusually strong El Niño effect from 1789 to 1793.[25]

Consequences in North America[edit]
In North America, the winter of 1784 was the longest and one of the coldest on record. It was the longest period of below-zero temperatures in New England, with the largest accumulation of snow in New Jersey, and the longest freezing over of Chesapeake Bay, where Annapolis, Maryland is, then the capital of the United States; the weather delayed Congressmen in coming to Annapolis to vote for the Treaty of Paris, which formally ended the American Revolutionary War. A huge snowstorm hit the South; the Mississippi River froze at New Orleans and there were reports of ice floes in the Gulf of Mexico.[24][26]

Contemporary reports[edit]
Gilbert White recorded his perceptions of the event at Selborne, Hampshire, England:
The summer of the year 1783 was an amazing and portentous one, and full of horrible phaenomena; for besides the alarming meteors and tremendous thunder-storms that affrighted and distressed the different counties of this kingdom, the peculiar haze, or smokey fog, that prevailed for many weeks in this island, and in every part of Europe, and even beyond its limits, was a most extraordinary appearance, unlike anything known within the memory of man. By my journal I find that I had noticed this strange occurrence from June 23 to July 20 inclusive, during which period the wind varied to every quarter without making any alteration in the air. The sun, at noon, looked as blank as a clouded moon, and shed a rust-coloured ferruginous light on the ground, and floors of rooms; but was particularly lurid and blood-coloured at rising and setting. All the time the heat was so intense that butchers' meat could hardly be eaten on the day after it was killed; and the flies swarmed so in the lanes and hedges that they rendered the horses half frantic, and riding irksome. The country people began to look, with a superstitious awe, at the red, louring aspect of the sun; [...][28
Benjamin Franklin recorded his observations in America in a 1784 lecture:
During several of the summer months of the year 1783, when the effect of the sun's rays to heat the earth in these northern regions should have been greater, there existed a constant fog over all Europe, and a great part of North America. This fog was of a permanent nature; it was dry, and the rays of the sun seemed to have little effect towards dissipating it, as they easily do a moist fog, arising from water. They were indeed rendered so faint in passing through it, that when collected in the focus of a burning glass they would scarce kindle brown paper. Of course, their summer effect in heating the Earth was exceedingly diminished. Hence the surface was early frozen. Hence the first snows remained on it unmelted, and received continual additions. Hence the air was more chilled, and the winds more severely cold. Hence perhaps the winter of 1783–4 was more severe than any that had happened for many years .The cause of this universal fog is not yet ascertained [...] or whether it was the vast quantity of smoke, long continuing, to issue during the summer from Hekla in Iceland, and that other volcano which arose out of the sea near that island, which smoke might be spread by various winds, over the northern part of the world, is yet uncertain.[29]"
https://en.wikipedia.org/wiki/Laki

But generally Iceland isn't much threat to Europe. In terms of number of people within the immediate danger zone and frequency of eruptions Vesuvius is the big danger, though in terms of the potential scale of an eruption and its consequences Santorini is the big granddaddy - the c 1613 BC eruption which took out the Minoan civilisation is now though to have been a VE7, second only to Tambora over the last few thousand years.