Eruption Clues: Researchers Create Snapshot Of Volcano Plumbing

Much like a forensic team recreates a scene to determine how a crime was committed, researchers at the University of New Hampshire are using scientific sleuthing to better understand the journey of magma, or molten rock, in one of Europe’s largest and most active volcanoes, Mount Etna. Researchers applied several techniques, in a new way, to create a more accurate picture of the volcano’s plumbing system and how quickly the magma rises to the top to cause an eruption. Their findings contribute to our understanding of how and when volcanoes erupt.

In their study, recently published in the journal Geochemical Perspective Letters, the UNH team set out to determine if the magma lingers below in pockets of the volcano or if it pushes up all at once. To put the pieces of the puzzle together, they combined three approaches previously not used together to reconstruct the ancient magma plumbing system by looking for chemical signatures in lava rock collected from flows on the surface. They looked at the minerals and the trace elements in the rocks because the tracers can help identify where the minerals have been by how they crystallized.

“As magma moves up through Earth’s crust beneath the volcano, it starts to crystallize,” says Sarah Miller, of UNH’s department of Earth sciences and lead author of the study. “Some elements move rapidly and some more slowly, so there is a chemical record of events in those crystals that can help us determine their journey.”

Extracting the timing and magma source information for ancient volcanism demonstrates how long-lived pre-eruptive processes of transport and storage work at Mount Etna. The researchers found a range of crystallization depths, suggesting there were discrete sites beneath the volcano where the rising magma crystallized. Their chemical forensic work showed two interesting things about the volcano. First, the source that produced magma in the ancient Mount Etna is much the same as what happens in Mount Etna in the present-day. Secondly, they showed that the crystals were virtually chemically identical to the lavas in which they erupted. This second finding suggests that in Mount Etna the length of time for crystal storage beneath the volcano is likely relatively short, a result which could help provide insight with recent findings for larger more explosive eruptive systems like Yellowstone.

“This proof-of-concept work puts us in a position to apply our approach more widely to other volcanoes,” said Julie Bryce, professor and chair of Earth sciences and a co-author of this paper. “Our work advances ways we can examine and think about volcanic plumbing systems beneath frequently active volcanic centers. Reconstructing the dynamics of these plumbing systems, and knowing how long-lived they are, helps in anticipating future changes in eruptive potential.”

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Iceland’s Biggest Active Volcano Shows Signs Of Reawakening

Iceland’s biggest active volcano is being kept under close surveillance amid signs it is waking up after centuries of slumber.

A new 1km-wide caldera – a basin-shaped volcanic depression – has been discovered by scientists in Öræfajökull, which translates as “wasteland”, in the south of the island.

The Icelandic Met Office has also received reports of the surrounding area smelling of sulphur, while geothermal water has been released from the volcano into a river on the surrounding glacier, reports Iceland Magazine.

Scientists believe this water caused a section of the volcano to collapse, producing the new caldera.

Although scientists say there are no imminent signs of an eruption, Iceland’s Civil Protection Agency has declared an uncertainty phase – a warning that there may be a threat in the near future – while its Met Office has issued a yellow warning.

Bryndís Ýr Gísladóttir, natural resource specialist at the Met Office, told newspaper Morgunbladid: “We issued a yellow warning for security reasons because we actually don’t know that much about Öræfajökull glacier, nor how it behaves because its last eruption occurred in 1727, and 1362 before that.”

Öræfajökull features Iceland’s highest peak and is thought to be one of the most powerful volcanoes in Europe. It is responsible for the country’s second deadliest eruption after a steam blast in 1362 deposited 10 cubic kilometres of debris across farmland and killed all inhabitants across dozens of farms.

Although still sparsely populated, the region can attract thousands of tourists at the height of the holiday season. The Icelandic Civil Protection Agency estimates there would only be a 20-minute warning before any eruption.

The volcano last erupted in 1727, and as a result volcanologists have a limited ability to predict when any eruption would occur.

With the growing seismic and geothermal activity of recent weeks, monitoring of the volcano is being increased.

Several Villages Hit By Volcanic Ash After Mt. Agung Erupts In Bali

Volcanic ash has fallen onto a number of villages surrounding Mount Agung in Bali following an eruption at the island’s tallest volcano on Tuesday afternoon, less than a month after the alert level was lowered.

At least five villages were affected by the ash, including Pidpid, Nawakerti, Bukit Galah, Sebudi and Abang Village. The villages are located within the danger zone of the volcano, kompas.com reported.

Authorities from the Energy and Mineral Resources Ministry’s Volcanology and Geological Hazard Mitigation Center (PVMBG) visited the villages following reports from local residents’ to authorities at the Mount Agung monitoring station.

“The PVMBG Emergency Response Team found [volcanic] ash, however, the intensity of the ash [falling on the villages] is still light,” head of mitigation sub-directorate at PVMBG, Devi Kemal, said on Tuesday evening.

Devi further advised residents not to panic and follow the authorities instructions. “Everyone should remain calm and follow PVMBG recommendations,” Devi said.

Mount Agung, which has been experiencing increased activity in recent months, erupted and spewed black smoke at 5:05 p.m. on Tuesday, with the height of the smoke reaching more than 700 meters from the peak of the mountain.

Residents are advised to stay away from areas within a 6 kilometer radius of the volcano. The volcano’s status is set at the third highest alert level, the National Disaster Mitigation Agency (BNPB) has previously said.

The alert level for the volcano that had forced more than 100,000 residents to flee was lowered late last month, from the highest level to the third highest level, although authorities said there was still a chance of eruption.

Magma Held In ‘Cold Storage’ Before Giant Volcano Eruption

Long Valley, California, has long defined the “super-eruption.” About 765,000 years ago, a pool of molten rock exploded into the sky. Within one nightmarish week, 760 cubic kilometers of lava and ash spewed out in the kind of volcanic cataclysm we hope never to witness.

The ash likely cooled the planet by shielding the sun, before settling across the western half of North America.

Here’s a rule of geoscience: The past heralds the future. So it’s not just morbid curiosity that attracts geoscientists to places like Long Valley. It’s an ardent desire to understand why super-eruptions happen, ultimately to understand where and when they are likely to occur again.

This week (Nov. 6, 2017), in the Proceedings of the National Academy of Sciences, a report shows that the giant body of magma — molten rock — at Long Valley was much cooler before the eruption than previously thought.

“The older view is that there’s a long period with a big tank of molten rock in the crust,” says first author Nathan Andersen, who recently graduated from the University of Wisconsin-Madison with a Ph.D. in geoscience. “But that idea is falling out of favor.

“A new view is that magma is stored for a long period in a state that is locked, cool, crystalline, and unable to produce an eruption. That dormant system would need a huge infusion of heat to erupt.”

It’s hard to understand how the rock could be heated from an estimated 400 degrees Celsius to the 700 to 850 degrees needed to erupt, but the main cause must be a quick rise of much hotter rock from deep below.

Instead of a long-lasting pool of molten rock, the crystals from solidified rock were incorporated shortly before the eruption, Andersen says. So the molten conditions likely lasted only a few decades, at most a few centuries. “Basically, the picture has evolved from the ‘big tank’ view to the ‘mush’ view, and now we propose that there is an underappreciation of the contribution of the truly cold, solidified rock.”

The new results are rooted in a detailed analysis of argon isotopes in crystals from the Bishop Tuff — the high-volume rock released when the Long Valley Caldera formed. Argon, produced by the radioactive decay of potassium, quickly escapes from hot crystals, so if the magma body that contained these crystals was uniformly hot before eruption, argon would not accumulate, and the dates for all 49 crystals should be the same.

And yet, using a new, high-precision mass spectrometer in the Geochronology Lab at UW-Madison, the research group’s dates spanned a 16,000 year range, indicating the presence of some argon that formed long before the eruption. That points to unexpectedly cool conditions before the giant eruption.

Better tools make better science, Andersen says. “The new instrument is more sensitive than its predecessors, so it can measure a smaller volume of gas with higher precision. When we looked in greater detail at single crystals, it became clear some must have been derived from magma that had completely solidified — transitioned from a mush to a rock.”

“Nathan found that about half of the crystals began to crystallize a few thousand years before the eruption, indicating cooler conditions,” says Brad Singer, a professor of geoscience at UW-Madison and director of the Geochronology Lab. “To get the true eruption age, you need to see the dispersion of dates. The youngest crystals show the date of eruption.”

The results have meaning beyond volcanology, however, as ash from Long Valley and other giant eruptions is commonly used for dating.

“These huge eruptions deposit ash all over the place, and that lets you make correlations in the rock record to aid geologic, biologic and climatic studies across the continent,” says Andersen. “This blanket of ash anchors you in time. The closer we can pin down the eruption age, the better we can study all facets of Earth’s history.”

“It’s controversial, but finding these older crystals means that part of this large magma body was very cool immediately prior to eruption,” says Singer, a volcanologist who was Andersen’s UW advisor. “This flies in the face of a lot of thermodynamics.”

A better understanding of the pre-eruption process could lead to better volcano forecasting — a highly useful but difficult proposition at present.

“This does not point to prediction in any concrete way,” says Singer, “but it does point to the fact that we don’t understand what is going on in these systems, in the period of 10 to 1,000 years that precedes a large eruption.”

Four Large Earthquakes In Iceland’s Most Powerful Volcano

Four large earthquakes occurred in the Bárðarbunga volcanic system last night, the largest earthquakes since the 2014-2015 volcanic eruption.

The first earthquake of magnitude 3.9 on the richter scale occured at 23:02 last night, followed by a 3.2 earthquake at 23:03. The third quake hit the volcano at 23:26 and measured 4.7. The fourth earthquake of magnitude 4.7 occured 16 minutes past midnight.

An earthquake measuring 4.1 took place in the volano earlier this week and several earthquakes hit the volcano in September.

Bárðarbunga is the largest and most powerful volcano in Iceland. It is located under the northern part of the Vatnajökull glacier in South Iceland, Europe’s largest glacier. The Bárðarbunga volcanic system is approximately 200 km (120 miles) long.

Earthquakes of magnitude 4.7 are the largest quakes that have occured in the Bárðarbunga caldera since the 2014 eruption. The Holuhraun eruption began on August 31st 2014 and lasted until February 28, 2015. It is the largest eruption in Iceland since 1783 and produced a massive lava field of more than 85 km2 (33 square miles) in the middle of the island.

Frozen Earth: The Planet Got Warm After Frequent Volcano Eruptions Melted The Last Ice Age

Fire melts ice, but so does ash: Dark particles settling onto white ice make the surface trap more heat, the same way wearing a black shirt on a sunny day is hotter than wearing a white shirt. And scientists have seen the connection play out in real time across Earth’s surface as volcanic eruptions have scattered ash on snow and made it melt faster. But for the first time, a team of researchers has pinpointed the phenomenon in the distant past, as they report in a new article published in the journal Nature Communications.

“The paper is the first to document that this phenomenon likely also occurred during the last deglaciation, and raises interesting questions regarding the role of volcanism on deglaciation,” James Baldini, an Earth scientist at Durham University in the U.K. not affiliated with the study wrote Newsweek in an email.

He notes that traditionally, scientists thinking about the impact of volcanoes on climate focus on tiny particles called aerosols, which are released during eruptions, form clouds that block sunlight and keep the Earth cooler. This paper, on the other hand, suggests that effect might have been balanced out by melting ice—leaving the planet no cooler than it was before.

The team used an unusual form of evidence: glacial varves, or the layers of dirt and mud deposited each year beneath a glacier. Just like the rings of new wood trees grow every year in a light-dark pattern, glaciers annually deposit first a wide lighter layer of sandier soil during the summer, then a narrower layer of darker clay during the winter. The thickness of each layer lets scientists calculate how much the glacier in question melted, since the more a glacier melts the more sediment it carries away.

He notes that traditionally, scientists thinking about the impact of volcanoes on climate focus on tiny particles called aerosols, which are released during eruptions, form clouds that block sunlight and keep the Earth cooler. This paper, on the other hand, suggests that effect might have been balanced out by melting ice—leaving the planet no cooler than it was before.

The team used an unusual form of evidence: glacial varves, or the layers of dirt and mud deposited each year beneath a glacier. Just like the rings of new wood trees grow every year in a light-dark pattern, glaciers annually deposit first a wide lighter layer of sandier soil during the summer, then a narrower layer of darker clay during the winter. The thickness of each layer lets scientists calculate how much the glacier in question melted, since the more a glacier melts the more sediment it carries away.

New Magma Pathways Develop After Lateral Collapse

Giant lateral collapses are huge landslides occurring at the flanks of a volcano. Giant lateral collapses are rather common events during the evolution of a large volcanic edifice, often with dramatic consequences such as tsunami and volcano explosions. These catastrophic events interact with the magmatic activity of the volcano, as a new research in Nature Communications suggests.

Giant lateral collapses may change the style of volcanism and the chemistry of magma, and as a new study by GFZ scientists reveals, also affects and diverges the deep paths of magmas. New volcano centers may form at other places, which the scientists explain by studying the stress field changes associated with the lateral collapse.

In the study entitled “The effect of giant lateral collapses on magma pathways and the location of volcanism”, authored by F. Maccaferri, N. Richter and T. Walter, all working at GFZ, in section 2.1 (Physics of earthquakes and volcanoes), the propagation path of magmatic intrusions underneath a volcanic edifice has been simulated by means of a mathematical model. Computer simulations revealed that the mechanical effect on the earth crust resulting from a large lateral collapse, can promote the deflection of deep magmatic intrusions, favoring the formation of a new eruptive center within the collapse embayment. This result has been quantitatively validated against observations at Fogo Volcano, Cabo Verde.

A broader view to other regions reveals that this shift of volcanism associated with giant lateral collapses is rather common, as observed at several of the Canary Islands, Hawaii, Stromboli and elsewhere. This study may have implications particularly for our understanding of the long term evolution of intraplate volcanic ocean islands and sheds lights on the interacting processes occurring during growth and collapse of volcanic edifices.