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  • richardmitnick 12:53 pm on December 3, 2019 Permalink | Reply
    Tags: "A Deep-Sea Magma Monster Gets a Body Scan", , , , Vulcanism   

    From The New York Times: “A Deep-Sea Magma Monster Gets a Body Scan” 

    New York Times

    From The New York Times

    Scientists set sail on a perilous expedition to create the first internal 3D images of Axial Seamount, an underwater volcano deep in the Pacific Ocean.

    1
    The caldera and rift zones of the Axial Seamount off the coast of Oregon, depicted as a computer generated 3D oblique view using seafloor bathymetry. The red zone is the shallowest area, and the blues and purples are as much as 2 miles deep.Credit Susan Merle, Oregon State University, CIMRS

    Dec. 3, 2019
    Robin George Andrews

    This summer, the 235-foot research vessel Marcus G. Langseth set out into the ocean off the Pacific Northwest. Trailing the ship were four electronic serpents, each five miles in length. These cables were adorned with scientific instruments able to peer into the beating heart of a monster a mile below the waves: Axial Seamount, a volcanic mountain.

    The ship’s crew had one overriding imperative: Do not let the cables get tangled.

    If they did, “it’s game over,” said Sam Mitchell, a submarine volcanologist who joined the voyage.

    The ship belongs to the National Science Foundation, and is operated by Columbia University’s Lamont-Doherty Earth Observatory. Scientists aboard spent 33 days in July and August hoping to create 3D maps of the magmatic ponds and pathways in an individual, active submarine volcano for the very first time. If the researchers succeeded, they would provide a view of a hyperactive volcano that had never been seen.

    Charting Axial’s internal anatomy also would improve scientists’ understanding of underwater volcanoes all over the world, most of which still lie waiting to be discovered in the gloomy depths.
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    The ship had to be steered carefully and couldn’t be stopped abruptly, or else those cables could settle, drift and become entangled, like earphones getting twisted in your pocket, only with profoundly expensive consequences.

    2
    Retrieving an air-gun array on the stern of the Marcus G. Langseth research vessel in Pacific northwest waters this summer.Credit Sam Mitchell

    Toward the end of the Langseth’s month at sea, what seemed like a nightmare began when one of the cables broke. Scientists deep within the hull of the ship, in a room full of screens that recorded the data streaming in, saw several monitors turn black. The cable’s GPS data indicated it was definitely not where it was supposed to be.

    For all the scientists knew, it could be lost at sea, gone forever.

    Compared to expeditions to volcanoes on land, those like the Marcus G. Langseth’s take years to prepare and have “several more zeros” added to their price tags, said Dr. Mitchell. Losing an entire family of probes and sensors to the Pacific would have been a stressful and costly accident.

    “You get one shot to do these expeditions,” he said.

    All eyes on Axial

    The volcano’s base would cover the entire city of Austin, Tex., said Adrien Arnulf, a seismologist at the University of Texas at Austin, the expedition’s principal investigator.

    It is far from the world’s largest volcano, but the walls of the horseshoe-shaped caldron at Axial’s peak are as high as the pillars of the Golden Gate Bridge. The volcano’s main magma reservoir is two-thirds of the length of Manhattan, the same width, and taller than any building in the city.

    Axial is also, volcanologically speaking, no shrinking violet.

    Over geological time, a stationary mantle plume below the shifting Pacific tectonic plate has created a 1,120-mile-long line of submarine volcanoes, known as the Cobb-Eickelberg seamount chain. Axial, the youngest member of the chain, is currently sitting atop that hot spot.

    The volcano also sits astride the mid-ocean ridge separating the Pacific plate to the west and the Juan de Fuca plate to the east. These plates are moving apart. Ridges like this are the birthplace of oceanic crust; molten rock rises from deep within the Earth to the seafloor, creating profuse volcanic activity.

    3
    Marine technicians and protected species observers kept an eye on monitors in the main lab aboard the Langseth.Credit Sam Mitchell

    This dual power of the plume and the moving ridge helps make Axial the most active submarine volcano in the region. It was erupting long before humans spotted it. So far, three eruptions — in 1998, 2011 and 2015 — have been documented as they occurred.

    Axial is remote and deep enough that it is vanishingly unlikely to ever cause anyone harm, said Ken Rubin, a volcanologist at the University of Hawaii at Manoa. But a better comprehension of Axial will help blunt hazards at other volcanoes that do pose risks. These include Hawaii’s Kilauea volcano, a veritable lava factory near plenty of people, and Anak Krakatau in Indonesia, which has shown how volcanoes growing out of the sea can trigger deadly mega-tsunamis.

    Axial’s hyperactivity and proximity to the mainland make it one of the most comprehensively researched and monitored submarine volcanoes in the world. It has been stared at by ships, visited up close by humans in submersibles and autonomous robot divers, and since late 2014, continuously monitored by an underwater observatory network known as the Cabled Array.

    The devil’s in the details

    Axial’s surface has been thoroughly studied, but what lies beneath remains far more ambiguous, said Annie Kell, a seismologist at the University of Nevada, Reno, who was part of the research effort.

    The only way to make sense of what happens when a volcano erupts is to peer inside. Earlier seismic scanning and listening to geological tremors have produced 2D cross-sections of parts of Axial, pinpointing key features like its faults, conduits, and primary and smaller magma reservoirs.

    Like physicians, volcanologists would be better placed to understand Axial if all of its volcanic organs, magmatic veins and geological bones could be precisely imaged and placed in true 3D — which is easier said than done.

    4
    On-board technicians and Michelle Lee, a student at the Lamont-Doherty Earth Observatory of Columbia University, center, kept records of instruments being added onto the cables during deployment of the 3D seismic array.Credit Steffen Saustrup

    Giving a land volcano a geological CT scan these days is relatively routine. Not so for underwater volcanoes. Their inaccessibility means that only part of the East Pacific Rise, a section of another mid-ocean ridge, has been subjected to the type of seismic scrutiny that Axial’s insides are getting, said Dr. Rubin.

    Key to the mission was a collection of pneumatic air guns, whose barrages of pressurized air created acoustic pulses. These pulses bounced around inside Axial before coming back to one of the many receivers on those cables, each of them drifting far from the ship’s own noise so as to obtain accurate readings.

    Those waves migrate through the subsurface differently depending on the properties of the rock they encounter. This behavior allows scientists to work out what is present within Axial, as well as how molten or solid each of its magmatic organs are. And with the Marcus G. Langseth’s more expansive and heavily equipped array of sensors, scientists would get their 3D view into an active submarine seamount for the first time.

    Praying to Poseidon

    As the vessel orbited above Axial, 50 scientists, students, technicians and crew members made sure everything was going according to plan. “It’s a small city, in a way,” said Dr. Arnulf.

    Data streamed in, but scientists had to take shifts watching the screens to make sure that it continued uninterrupted. It was a bit like a less thrilling version of watching the screens of green code in “The Matrix.”

    “You barely see the sun, because you’re often in the hull of the boat,” said Dr. Arnulf. Spacing out was to be expected from time to time.

    Everyone played their parts, but luck wasn’t always on their side. That snapped cable, perhaps caused by the tremendous physical strain it and the other components of the ship’s sensors were often under, provided an unwelcome dose of jeopardy.

    “That was a very, very tense day,” Dr. Mitchell added.

    5
    Victoire Lucas, a student at Université de Bretagne Occidentale in France, kept an eye on the spools being used to deploy cables in the ship’s stern.Credit Sam Mitchell

    Fortunately, the cable was found clinging on, somehow still attached to the ship. Because it could not be repaired at sea, the team had to finish the mission with just three cables.

    At another point, the engine decided to throw a fit, requiring the team to power down the entire ship and spend the next 18 hours or so carefully reeling the four 55-ton cables back onto the vessel. The engine was fixed within an hour, but unspooling the lines again required another day. That stole two days from the cruise.

    Dr. Kell, choosing to stay back on land with her children, gave mission support to the Langseth and shared the crew’s moments of technological peril. With these sorts of expeditions, so much is on the line that, she said, “you have to channel an inner peace, even though your nerves are like, oh my gosh, this is all about to go out the window!”

    Dr. Arnulf was more nonchalant. “I don’t think I’ve ever been on a cruise where everything goes smoothly,” he said. “You’re always losing instruments.”

    For most of the students, it was the first time at sea, so it was important to keep them entertained, said Dr. Mitchell.

    Plenty of bets were wagered on ludicrous things, like how many eggs were brought on board (2,880) or how many springs were in a single air gun (24). Between shifts, people completed theses, wrote papers, read books. Dr. Arnulf, training for extreme sporting events on land, spent a fair amount of time in the gym.

    Curiosity killed the cruise

    Technical hitches weren’t all the team had to worry about. Local wildlife, such as fin whales, dolphins, sharks and sunfish had the potential to scupper the expedition.

    Officers on deck kept an eye out for aquatic interlopers while using hydrophones to listen underwater. Marine mammals are dependent on acoustic communications, so if any got within 3,300 feet of the ship, the booming seismic equipment had to be shut down.

    “You are basically creating a sound in the ocean every 15 seconds, and it’s a big sound,” said Dr. Mitchell.

    Younger critters triggered a shutdown of all the equipment if they were seen at any distance. To an infant blue whale, the pulses made by the ship’s array would be like screams in its ear.

    Those officers, understandably, had a lot of science-stopping power. Many things could jeopardize the mission, but Dr. Mitchell said it was surreal to think that half a decade of preparation could be nixed by a persistently curious baby whale refusing to leave the ship’s side.

    Stitching together a masterpiece


    An early 3D view of Axial and its magma reservoirs.

    Despite a few moments of chaos, the voyage achieved its objective. With the expedition concluded, scientists are now digging into all of the Langseth’s seismic slices and stitching all the data together to form a proper 3D view of Axial’s guts.

    It is already clear that the Langseth’s data has game-changing potential.

    The roofs of the primary and secondary magma chambers can be clearly seen in three dimensions. Their complexities are becoming clear: multiple horizontal wafers of magma, known as sills, streak through the subsurface. A previously discovered field of hydrothermal vents, some as high as buildings, has been found sitting above a newly identified third magma cache.

    As they learn more about what the crew of the Langseth found, scientists stand to better understand other volcanoes, particularly those hidden beneath the sea. “A significant fraction of Earth’s volcanism happens at places like Axial,” said Dr. Rubin, referring to the mid-ocean ridges, which collectively represent a spine of volcanism stretching about 40,000 miles around the world.

    But it won’t be a breeze to finish this work. Years of processing and analysis lies ahead.

    “There really is both a science and an art to processing and interpreting seismic data,” said Jackie Caplan-Auerbach, a seismologist and volcanologist at Western Washington University. Compared to 2D profiles, “3D seismic data is an order of magnitude more challenging.”

    The mission’s data might also help scientists better understand why Axial seems to be breathing.

    When magma is rising to the surface, volcanoes tend to inflate, and Axial is no exception. Using a special arrangement of pressure sensors beneath the waves, Dr. Chadwick and his colleagues found that “if Axial’s not erupting, it’s reinflating.”


    The sensor cables extended at sea.Credit Sam Mitchell

    Right after one eruption ends, the volcano immediately begins refueling for the next one, getting to roughly the same level each time before it blows its top.

    This rhythm allowed these scientists to predict the timing of its two most recent eruptions with ever-increasing precision. “It seems fairly well behaved, at least so far,” said Dr. Chadwick.

    The next eruption is predicted to be in 2020 or 2021. Whether or not scientists achieve this forecasting hat trick, these cycles of inflation and eruption will make more sense as Axial’s magma caches come into focus.

    Surface deformation is one of the main ways in which volcanoes of all kinds are monitored, from Washington State’s explosive Mount St. Helens to Hawaii’s effusive Mauna Loa. With a more holistic model of Axial and its balloon-like behavior, scientists may better understand or identify the precursors of eruptions at these volcanoes, too.

    Dr. Arnulf said that members of the public can ask how an expedition to a volcano far from anyone benefits society in terms of financial gain or hazard mitigation. But, he said, anyone raising these questions might as well ask why astronomers bother studying the stars.

    For him and his colleagues, gazing into the Hadean labyrinths of a restless underwater volcano holds another, more visceral appeal.

    “It’s freaking awesome,” he said.

    See the full article here .

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  • richardmitnick 10:22 am on November 14, 2019 Permalink | Reply
    Tags: "Volcanoes under pressure", , The volcano Merapi on the island Java in Indonesia., , Vulcanism   

    From Techniche Universitat Munchen: “Volcanoes under pressure” 

    Techniche Universitat Munchen

    From Techniche Universitat Munchen

    13.11.2019
    Prof. Dr. H. Albert Gilg
    Technical University of Munich
    Professorship for Engineering Geology
    agilg@tum.de

    1
    The volcano Merapi on the island Java in Indonesia. Image: iStock_mazzzur

    Researchers unlock the secret of explosive volcanism.

    When will the next eruption take place? Examination of samples from Indonesia’s Mount Merapi show that the explosivity of stratovolcanoes rises when mineral-rich gases seal the pores and microcracks in the uppermost layers of stone. These findings result in new possibilities for the prediction of an eruption.

    Mount Merapi on Java is among the most dangerous volcanoes in the world. Geoscientists have usually used seismic measurements which illustrate underground movements when warning the population of a coming eruption in time.

    An international team including scientists from the Technical University of Munich (TUM) has now found another indication for an upcoming eruption in the lava from the peak of Mount Merapi: The uppermost layer of stone, the “plug dome”, becomes impermeable for underground gases before the volcano erupts.

    “Our investigations show that the physical properties of the plug dome change over time,” says Prof. H. Albert Gilg from the TUM Professorship for Engineering Geology . “Following an eruption the lava is still easily permeable, but this permeability then sinks over time. Gases are trapped, pressure rises and finally the plug dome bursts in a violent explosion.”

    Mount Merapi as a model volcano

    Using six lava samples, one from an eruption of Mount Merapi in 2006, the others from the 1902 eruption – the researchers were able to ascertain alterations in the stone. Investigation of pore volumes, densities, mineral composition and structure revealed that permeability dropped by four orders of magnitude as stone alteration increased. The cause is newly formed minerals, in particular potassium and sodium aluminum sulfates which seal the fine cracks and pores in the lava.

    The cycle of destruction

    Computer simulations confirmed that the reduced permeability of the plug dome was actually responsible for the next eruption. The models show that a stratovolcano like Mount Merapi undergoes three phases: First, after an eruption when the lava is still permeable, outgassing is possible; in the second phase the plug dome becomes impermeable for gases, while at the same time the internal pressure continuously increases; in the third phase the pressure bursts the plug dome.

    Photographs of Mount Merapi from the period before and during the eruption of May 11, 2018 support the three-phase model: The volcano first emitted smoke, then seemed to be quiet for a long time until the gas found an escape and shot a fountain of ashes kilometers up into the sky.

    “The research results can now be used to more reliably predict eruptions,” says Gilg. “A measurable reduction in outgassing is thus an indication of an imminent eruption.”

    Mount Merapi is not the only volcano where outgassing measurements can help in the timely prediction of a pending eruption. Stratovolcanoes are a frequent source of destruction throughout the Pacific. The most famous examples are Mount Pinatubo in the Philippines, Mount St. Helens in the western USA and Mount Fuji in Japan.

    Science article:
    Hydrothermal alteration of andesitic lava domes can lead to explosive volcanic behaviour
    Nature Communications

    See the full article here .

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    Techniche Universitat Munchin Campus

    Techniche Universitat Munchin is one of Europe’s top universities. It is committed to excellence in research and teaching, interdisciplinary education and the active promotion of promising young scientists. The university also forges strong links with companies and scientific institutions across the world. TUM was one of the first universities in Germany to be named a University of Excellence. Moreover, TUM regularly ranks among the best European universities in international rankings.

     
  • richardmitnick 11:24 am on July 31, 2019 Permalink | Reply
    Tags: "A Tectonic Plate Under Oregon Is Being Slowly Ripped Apart", , , , Juan de Fuca tectonic plate, , , Vulcanism   

    From UC Berkeley via Science Alert: “A Tectonic Plate Under Oregon Is Being Slowly Ripped Apart” 

    From UC Berkeley

    via

    ScienceAlert

    Science Alert

    31 JUL 2019
    DAVID NIELD

    Spare a thought for the Juan de Fuca tectonic plate, not long for this world (in tectonic plate terms) as it slowly slides under the continent of North America.

    3
    Map of the Juan de Fuca Plate. No image credit. Wikipedia.

    Geologists are hoping it can help solve one of the biggest mysteries in their field – how tectonic plates die.

    The Juan de Fuca plate is the last remnant of the much bigger Farallon plate, which has been disappearing under North America for tens of millions of years. It’s the perfect opportunity to study how plates eventually get swallowed up, and how that might cause seismic and volcanic activity on the surface.

    In particular, researchers William Hawley and Richard Allen, from the University of California, Berkeley, are interested in a gap that’s appearing in the Juan de Fuca plate – which may in fact represent a tearing of the plate way down below the surface.

    “The tearing not only causes volcanism on North America but also causes deformation of the not‐yet‐subducted sections of the oceanic plate offshore,” write the researchers in their newly published paper [Geophysical Letters Research].

    “This tearing may eventually cause the plate to fragment, and what is left of the small pieces of the plate will attach to other plates nearby.”

    All the rock that gets buried as a plate is subsumed has to go somewhere, and the large-scale deformations and breaks that can occur aren’t easy for scientists to predict or map.

    Using data from 217 earthquakes and more than 30,000 seismic waves, Hawley and Allen have been able to put together a detailed 3D picture of this particular part of the Cascadia Subduction Zone.

    2
    Cascadia subduction zone. USGS.

    Specifically, they identified which parts of the rock were from the Juan de Fuca plate.

    They found what looks like a tear more than 150 kilometres (93 miles) deep, and it matches a previously identified area of weakness on the Juan de Fuca plate at the surface, known as a propagator wake.

    The researchers suggest that as the Juan de Fuca plate turns and twists, parts of it are being pulled off and separated, creating the gap that experts have observed. Some of it might even live on as part of another plate.

    More evidence is needed to be sure of what is happening here, but the hypothesis matches seismic activity around southern Oregon and northern California, as well as unusual patterns of volcanism in the region.

    Those unusual patterns are the volcanoes known as the High Lava Plains in southern Oregon, where the newest eruptions are at the wrong end of the series from where geologists would expect them to be, based on the direction of drift of the North American tectonic plate.

    Fresh volcanic activity caused by the propagator wake and deeper weakness in the Juan de Fuca could perhaps explain this anomaly, the researchers suggest.

    As Juan de Fuca disappears, further research – as well as readings from the EarthScope project and the Cascadia Initiative, which were used in this study – should shed more light on how tectonic plates die, and how they’ve formed the world we live on.

    “In many ways, when we’re looking at these things, we’re looking back in time,” seismologist Lara Wagner from the Carnegie Institution for Science, who wasn’t involved in the study, told National Geographic.

    “If we don’t understand how those processes work[ed] in the past, where we can see the whole story and study it, then our chances of seeing what’s happening today and understanding how that might evolve in the future are zero.”

    See the full article here .

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  • richardmitnick 4:06 pm on February 28, 2018 Permalink | Reply
    Tags: , , , Vulcanism   

    From Carnegie Institution for Science: “Modern volcanism tied to events occurring soon after Earth’s birth” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    February 27, 2018

    Plumes of hot magma from the volcanic hotspot that formed Réunion Island in the Indian Ocean rise from an unusually primitive source deep beneath the Earth’s surface, according to new work in Nature from Carnegie’s Bradley Peters, Richard Carlson, and Mary Horan along with James Day of the Scripps Institution of Oceanography.

    Réunion marks the present-day location of the hotspot that 66 million years ago erupted the Deccan Traps flood basalts, which cover most of India and may have contributed to the extinction of the dinosaurs. Flood basalts and other hotspot lavas are thought to originate from different portions of Earth’s deep interior than most volcanoes at Earth’s surface and studying this material may help scientists understand our home planet’s evolution.

    1
    A fieldwork photo from Réunion Island shows the flank of the Cirque de Cilaos, looking out towards the Indian Ocean courtesy of Bradley Peters.

    3
    Looking into down into a volcanic crater of Piton de la Fournaise on Réunion Island with dormant volcanic cones in the background. Photo is courtesy of Bradley Peters.

    The heat from Earth’s formation process caused extensive melting of the planet, leading Earth to separate into two layers when the denser iron metal sank inward toward the center, creating the core and leaving the silicate-rich mantle floating above.

    Over the subsequent 4.5 billion years of Earth’s evolution, deep portions of the mantle would rise upwards, melt, and then separate once again by density, creating Earth’s crust and changing the chemical composition of Earth’s interior in the process. As crust sinks back into Earth’s interior—a phenomenon that’s occurring today along the boundary of the Pacific Ocean—the slow motion of Earth’s mantle works to stir these materials, along with their distinct chemistry, back into the deep Earth.

    But not all of the mantle is as well-blended as this process would indicate. Some older patches still exist—like powdery pockets in a poorly mixed bowl of cake batter. Analysis of the chemical compositions of Réunion Island volcanic rocks indicate that their source material is different from other, better-mixed parts of the modern mantle.

    Using new isotope data, the research team revealed that Réunion lavas originate from regions of the mantle that were isolated from the broader, well-blended mantle. These isolated pockets were formed within the first ten percent of Earth’s history.

    Isotopes are elements that have the same number of protons, but a different number of neutrons. Sometimes, the number of neutrons present in the nucleus make an isotope unstable; to gain stability, the isotope will release energetic particles in the process of radioactive decay. This process alters its number of protons and neutrons and transforms it into a different element. This new study harnesses this process to provide a fingerprint for the age and history of distinct mantle pockets.

    Samarium-146 is one such unstable, or radioactive, isotope with a half-life of only 103 million years. It decays to the isotope neodymium-142. Although samarium-146 was present when Earth formed, it became extinct very early in Earth’s infancy, meaning neodymium-142 provides a good record of Earth’s earliest history, but no record of the Earth from the period after all the samarium-146 transformed into neodymium-142. Differences in the abundances of neodymium-142 in comparison to other isotopes of neodymium could only have been generated by changes in the chemical composition of the mantle that occurred in the first 500 million years of Earth’s 4.5 billion-year history.

    The ratio of neodymium-142 to neodymium-144 in Réunion volcanic rocks, together with the results of lab-based mimicry and modeling studies, indicate that despite billions of years of mantle mixing, Réunion plume magma likely originates from a preserved pocket of the mantle that experienced a compositional change caused by large-scale melting of the Earth’s earliest mantle.

    The team’s findings could also help explain the origin of dense regions right at the boundary of the core and mantle called large low shear velocity provinces (LLSVPs) and ultralow velocity zones (ULVZs), reflecting the unusually slow speed of seismic waves as they travel through these regions of the deep mantle. Such regions may be relics of early melting events.

    “The mantle differentiation event preserved in these hotspot plumes can both teach us about early Earth geochemical processes and explain the mysterious seismic signatures created by these dense deep-mantle zones,” said lead author Peters.

    Funding for fieldwork for this study was provided by the National Geographic Society (NGS 8330-07), the Geological Society of America (GSA 10539-14), and by a generous personal donation from Dr. R. Rex. Support for laboratory work was provided by Carnegie Institution for Science.

    See the full article here .

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    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 5:54 am on May 16, 2017 Permalink | Reply
    Tags: , Campi Flegrei volcano, , Vulcanism   

    From COSMOS: “A sleeping Italian supervolcano rumbles closer to eruption” 

    Cosmos Magazine bloc

    COSMOS

    16 May 2017
    Jessica Snir

    1
    A crate full of sulphurous rocks surrounded by steam and smoke from the Solfatara volcano, part of the Campi Flegrei. Andrea Pistolesi

    The Campi Flegrei volcano situated to the west of Naples in southern Italy has been stirring for the past 67 years. Similar stirrings were recorded for a century before its last great week-long eruption, in 1538.

    Now, new research from University College London (UDL) and the Vesuvius Observatory in Naples suggests that another eruption of the supervolcano may be more imminent than previously anticipated.

    The research, published in Nature Communications, finds that the periods of unrest occurring intermittently since the 1950s – namely small-scale, local earthquakes and ground uplifts – have led to the accumulation of energy within the volcanic crust and an increased susceptibility to eruption.

    The discovery of this cumulative effect is contrary to an earlier belief that the energy built up during each period of unrest dissipated afterwards.

    To investigate the activity of Campi Flegrei and attempt to forecast future eruptions, the researchers utilised a new model of volcano fracturing developed at UCL involving detailed physical models of how the ground is cracking and moving at the site.

    “We don’t know when or if this long-term unrest will lead to an eruption, but Campi Fleigrei is following a trend we’ve seen when testing our model on other volcanoes,” explains Dr Christopher Kilburn of UCL. “It may be approaching a critical stage where further unrest will increase the possibility of an eruption.”

    Rather than a conical mountain-like volcano, Campi Flegrei manifests as a large caldera, an enormous depression in the surface, covering a colossal 100 square kilometres.

    Episodes of unrest since 1950 have together raised the port of Pozzuoli more than three metres out of the sea and forced the evacuation of the town.

    An eruption of Campi Fleigrei now would devastatingly affect not only the 360,000 residents of the caldera region but also the nearly one million people in neighbouring Naples.

    “We must be ready for a greater amount of local seismicity,” explained Professor Giuseppe De Natale, former Director of the Vesuvius Observatory. “We must adapt our preparations for another emergency.”

    See the full article here .

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  • richardmitnick 12:52 pm on May 4, 2017 Permalink | Reply
    Tags: , , Hawaii volcanoes, Hot spot, Pacific Plate, Tectonic swerve responsible for creation of Hawaiian islands, Vulcanism   

    From COSMOS: “Tectonic swerve responsible for creation of Hawaiian islands” 

    Cosmos Magazine bloc

    COSMOS

    04 May 2017
    Andrew Masterson

    A change in direction of the Pacific Plate 3 million years ago created the conditions for turbulent volcanic eruptions.

    1
    Pu‘u ‘O‘o, a volcanic cone on Kilauea, Hawaii. G. E. Ulrich

    Hawaii was born in fire and eruption and today boasts the biggest and most active volcanoes in the world – a fact that has long puzzled geologists.

    The islands – which together comprise 20 extinct or active volcanoes – are situated well away from tectonic plate boundaries, the moving stress zones that typically produce volcanism.

    Now, however, questions surrounding the mysteries of Hawaii’s origin have been answered, thanks to research led by Tim Jones from Australian National University.

    The research, published in Nature, found that the volcanoes were catalysed three million years ago by a sudden change of direction by the Pacific Plate, the 103-million-square-kilometre tectonic plate that has Baja California at one end, New Zealand at the other – and Hawaii pretty much in the middle.

    As early as 1849, geologists – notably American explorer James Dwight Dana – suggested that Hawaii arose because the earth beneath the seabed was moving in two directions.

    In 1963, Canadian geophysicist J. Tuzo Wilson developed the theory by posting the existence of a “hot spot” – a section of the mantle through which a thermal plume rises, melting the rock above. Magma from beneath the mantle rises up, and forms a volcano. Gradually, each new volcano moves away from the hotspot, which then repeats the process.

    Indeed, the volcanoes and submerged mountains that extend northwest from Hawaii grow progressively more ancient the further away they are from the islands.

    Using complex computer modeling, Jones and colleague Rhodri Davies have effectively confirmed Dana’s and Wilson’s insights.

    “The analysis we did on past Pacific Plate motions is the first to reveal that there was a substantial change in motion three million years ago,” says Jones.

    “It helps to explain the origin of Hawaii, Earth’s biggest volcanic hotspot.”

    Once the critical section of the Pacific Plate had shifted course, its movement was at odds with the force of the thermal plume, thus creating the conditions for turbulent eruptions.

    The change of direction that caused the volcanic birth of the islands is not unique. Jones said something similar happened to bring Samoa into existence, at roughly the same time.

    Three million years might seem like a very long period, but in geologic terms it is nothing special. At some point in the future, the researchers predict, the misalignment of plate and plume may well fix itself.

    “Our hypothesis predicts that the plate and the plume will realign again at some stage in the future, and the two tracks will merge to form a single track once again,” says Davies.

    See the full article here .

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  • richardmitnick 11:17 am on March 14, 2017 Permalink | Reply
    Tags: , Deccan Traps, Earth’s lost history of planet-altering eruptions revealed, Enormous volcanoes vomited lava over the ancient Earth, Venus Mars Mercury and the Moon all show signs of enormous eruptions, Vulcanism   

    From Nature: “Earth’s lost history of planet-altering eruptions revealed” 

    Nature Mag
    Nature

    14 March 2017
    Alexandra Witze

    1
    India’s Western Ghats mountains contain igneous rock deposited 66 million years ago by a volcanic eruption in the Deccan Traps. Dinodia Photos/Getty

    Enormous volcanoes vomited lava over the ancient Earth much more often than geologists had suspected. Eruptions as big as the biggest previously known ones happened at least 10 times in the past 3 billion years, an analysis of the geological record shows.

    Such eruptions are linked with some of the most profound changes in Earth’s history. These include the biggest mass extinction, which happened 252 million years ago when volcanoes blanketed Siberia with molten rock and poisonous gases.

    “As we go back in time, we’re discovering events that are every bit as big,” says Richard Ernst, a geologist at Carleton University in Ottawa, Canada, and Tomsk State University in Russia, who led the work. “These are magnificent huge things.”

    Knowing when and where such eruptions occurred can help geologists to pinpoint ore deposits, reconstruct past supercontinents and understand the birth of planetary crust. Studying this type of volcanic activity on other planets can even reveal clues to the geological history of the early Earth.

    Ernst presented the findings this month to an industry consortium that funded the work (see ‘Earth’s biggest eruptions’). He expects to make the data public by the end of the year, through a map from the Commission for the Geological Map of the World in Paris.

    2

    “This will probably be the defining database for the next decade,” says Mike Coffin, a marine geophysicist at the University of Tasmania in Hobart, Australia.

    Surprisingly, the ancient eruptions lurk almost in plain sight. The lava they spewed has long since eroded away, but the underlying plumbing that funnelled molten rock from deep in the Earth up through the volcanoes is still there.

    Telltale tips

    Ernst and his colleagues scoured the globe for traces of this plumbing. It usually appears as radial spokes of ancient squirts of lava, fanned out around the throat of a long-gone volcano. The geologists mapped these features, known as dyke swarms, and used uranium–lead dating to pinpoint the age of the rock in each dyke. By matching the ages of the dykes, the researchers could connect those that came from a single huge eruption. During their survey, they found evidence of many of these major volcanic events.

    Each of those newly identified eruptions goes into Ernst’s database. “We’ve got about 10 or 15 so far that are probably comparable to the Siberian event,” Ernst says, “that we either didn’t know about or had a little taste, but no idea of their true extent.”

    They include a 1.32-billion-year-old eruption in Australia that connects to one in northern China. By linking dyke swarms across continents, scientists can better understand how Earth’s crust has shuffled around over time, says Nasrrddine Youbi, a geologist at Cadi Ayyad University in Marrakesh.

    Technically, the eruptions are known as ‘large igneous provinces’ (LIPs). They can spew more than one million cubic kilometres of rock in a few million years. By comparison, the 1980 eruption of Mount St Helens in Washington state put out just 10 cubic kilometres.

    These large events also emit gases that can change atmospheric temperature and ocean chemistry in a geological blink of an eye. A modelling study published last month suggests that global temperatures could have soared by as much as 7 °C per year at the height of the Siberian eruptions (F. Stordal et al. Palaeogeogr. Palaeoclimatol. Palaeoecol. 471, 96–107; 2017). Sulfur particles from the eruptions would have soon led to global cooling and acid rain; more than 96% of marine species went extinct.

    But the picture of how LIPs affected the global environment gets murkier the further back in time you get, says Morgan Jones, a volcanologist at the University of Oslo. Uncertainties in dating grow, and it becomes hard to correlate individual eruptions with specific environmental impacts. “It’s at the limit of our understanding,” he says.

    On average, LIPs occur every 20 million years or so. The most recent one was the Columbia River eruption 17 million years ago, in what is now the northwestern United States.

    Discovering more LIPs on Earth helps to put the geological history of neighbouring planets in perspective, says Tracy Gregg, a volcanologist at the University at Buffalo in New York. She and Ernst will lead a meeting on LIPs across the Solar System at a planetary-science meeting in Texas next week.

    Venus, Mars, Mercury and the Moon all show signs of enormous eruptions, Gregg notes. On the Moon, LIP-style volcanism started as early as 3.8 billion years ago; on Mars, possibly 3.5 billion years ago. But without plate tectonics to keep the surface active, those eruptions eventually ceased.

    “Other planetary bodies retain information about the earliest parts of planetary evolution, information that we’ve lost on Earth,” Gregg says. “They can give us a window into the early history of our own planet.”

    See the full article here .

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 10:02 am on March 13, 2017 Permalink | Reply
    Tags: , , , Vulcanism   

    From Eos: “Tracking Volcanic Bombs in Three Dimensions” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    3.13.17
    Leah Crane

    1
    Off the north coast of Sicily, an eruption of the Stromboli volcano sends decametric lava fragments flying into the air. A new method allows researchers to track these “bombs” and to reconstruct their flight trajectories in three dimensions. Credit: Florian Becker/Vulkankultour

    In explosive volcanic eruptions, bits of fragmented magma can be shot through the air by the release and expansion of pressurized gas. The trajectory map of these centimetric to decametric fragments, called “bombs,” is an important parameter in the study of explosive eruptions and the dangers that they present: Understanding how fast the debris is moving, how far it moves, and in which direction pieces travel could help scientists assess the hazards of volcanic eruptions or man-made explosions. In a new paper, Gaudin et al . present a method for studying the motion of volcanic bombs in three dimensions, allowing for more precise trajectory reconstructions.

    There are several conditions that make observing active volcanic vents and bombs difficult, including the obvious difficulty of getting cameras close to the vents. The most significant of the problems is the large number of bombs from each explosive event that may change shape in flight and whose flight paths overlap with one another.

    2
    When observing a bubble bursting in Halema‘uma‘u lava lake in Hawaii, researchers manually tracked selected pieces of debris on stills of a video. These two images of the resulting set of trajectories could then be combined to produce a three-dimensional map. Credit: Gaudin et al. [2016]

    These limitations make any automatic tracking difficult or impossible, so the scientists simplified their procedure by relying on manual tracking of a few representative bombs rather than a computerized account of every single one. By placing two or more high-speed video cameras at well-documented positions around the volcanic vent, they were able to manually determine an object’s location in all of the images, computing the object’s position in three dimensions.

    The human component of this manual process can be a major source of error since the person tracking the bombs makes a series of subjective choices, like deciding where exactly on the object to select as a representative point in each frame. If the cameras are tilted at all, that can also be a significant component of uncertainty in the measurements.

    In the new study, the team was able to reduce uncertainty to 10° in angle and 20% in speed of the bombs. They used three events as examples: a bursting bubble at the Halema‘uma‘u lava lake in Hawaii, in-flight bomb collision, and an explosive ejection event at Stromboli volcano in Italy. A video showing the bursting bubble followed by the explosive ejection and their model in action is given below.


    In Stromboli’s case, the reliability of the trajectory reconstruction was demonstrated by comparing the 3-D reconstruction with the low-speed, low-resolution cameras of the Stromboli permanent monitoring network. These case studies demonstrated just a few of the numerous contexts in which this 3-D tracking method could be useful, both within and beyond the study of volcanic vents and magma. (Geochemistry, Geophysics, Geosystems, https://doi.org/10.1002/2016GC006560, 2016)

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 8:40 pm on March 10, 2017 Permalink | Reply
    Tags: , , , , Planetary scientists are turning up volcanoes everywhere they look, Vulcanism   

    From Astronomy: “Planetary scientists are turning up volcanoes everywhere they look” 

    Astronomy magazine

    Astronomy Magazine

    March 6, 2017
    Stephanie Margaret Bucklin

    1
    Jupiter’s moon Io is the most volcanically active place in the solar system thanks to a rough tug from mighty Jupiter that warps the planet’s interior structure.

    Our closest planetary neighbor shares a surprising feature with Earth: volcanoes. A new study, published February 1st in the journal Science Advances, revealed interesting new details about the volcanic history of Mars. Thomas Lapen, first author of the paper and Professor of Geology at the University of Houston, told Astronomy that their analysis of Martian meteorites showed that volcanic activity on Mars has been ongoing since at least 2.4 to 0.15 billion years ago—and likely continues today.

    Given that the meteorites Lapen and his group studied came from a single ejection site on Mars, they reveal over 2 billion years of stacked lava flows, Lapen said. The discovery could help scientists decipher more about how often volcanoes erupted on Mars, as well as time periods when they were most active.

    Lapen explained that the type of volcanic activity that occurs on Mars is called basaltic volcanism, which is similar to the type of volcanism seen, for example, in volcanoes in Hawaii. These types of volcanoes produce fluid lava and are rarely explosive.

    But Mars isn’t the only extraterrestrial body with volcanoes. Volcanoes—in various forms—are also found on other planets, moons, and even asteroids. Take, for instance, Jupiter’s moon Io, which has active volcanoes that spew gas and melted rock, or Venus, which is covered with over 1,000 volcanoes, according to NASA. It’s not yet determined whether these venusian volcanoes are active or not.

    2
    Triton, the largest moon of Neptune, displayed evidence of geysers and other cryovolcanic activity when Voyager 2 swept past it in 1989. NASA / JPL-Caltech

    Cold as ice

    Then there’s a whole other type of volcanism, called cryovolcanism. As NASA explains in this interactive graphic, cryovolcanoes erupt water and gases rather than melted rocks. They dot a number of different bodies in our solar system, include Neptune’s moon Triton and Saturn’s moon Enceladus.

    “It’s a form of volcanism because volcanism is a process that brings material from the interior to the surface, but it is not molten rock,” Dr. Rosaly Lopes, Senior Research Scientist at NASA’s Jet Propulsion Laboratory, told Astronomy. Instead, cryovolcanoes occur on bodies with an ocean situated beneath an icy crust. When pressure builds up, it is released in the form of geysers of water mixed with ammonia or methane.

    Generally, cryovolcanoes are found on bodies in the outer solar system, Lopes said, though scientists also believe that cryovolcanism may even have happened on the asteroid / dwarf planet Ceres. According to recent studies from the Max Plancke Center for Solar System Research, several structures in Occator Crater suggest recent geologic activity consistent with cryovolcanic activity, though to date only one “mountain” has been found on the world.

    Information about these volcanoes provides scientists with clues about important geological processes. “Volcanism is one of the major, really fundamental processes that shapes the surface of a planet or moon,” Lopes said. That shape, she explained, comes from the interplay of four major processes — volcanism, tectonism, erosion, and impact cratering. Understanding volcanism’s role in shaping a body’s surface provides a crucial clue in understanding more about the geological processes of that planet.

    “For example,” Lopes told Astronomy, “if Earth was the only place we had seen volcanism, we might think that volcanism really depends on plate tectonics…But when we look at the other planets, we see that they have or have had volcanism in the past, and there is no plate tectonics.”

    She cited Io as one instance of this: when scientists saw the incredibly active volcanism occurring there, they realized that it was tidal heating that caused this volcanism. It works like this: Io and other Galilean satellites (such as Europa and Ganymede) are in synchronous rotation around Jupiter. Io then becomes caught up in a tug of war between Jupiter’s gravity and the gravity of these other satellites, Lopes explained. This in turn leads to the bulging of Io’s crust up and down, and the resulting friction produces a large amount of heat and a molten interior. When the pressure builds, it occasionally erupts melted rock and plumes of gas.

    Recent evidence even suggests that they may appear on comets. Comet 29P/Schwassmann-Wachmann displays outbursts on carbon monoxide consistent with other forms of cryovolcanism around the solar system. The outbursts seem to happen from one spot on the comet — making it one of the smallest bodies believed to have signs of volcanism.

    While volcanoes can shed light on certain geological processes, there’s another, even more intriguing reason to search for them: they may be indicators of climates suitable for life. Volcanism provides heat and energy, which is essential for life, Lopes said. And cryovolcanism has not only heat, but water—two of the essential ingredients of life. That doesn’t mean that every body with cryovolcanism has the necessary conditions to support life, of course. But those planets may not be a bad place to start.

    See the full article here .

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