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  • richardmitnick 11:58 am on June 30, 2017 Permalink | Reply
    Tags: , , Supervolcanoes, The Yellowstone Supervolcano Has Just Seen 878 Earthquakes in Two Weeks,   

    From Science Alert: “The Yellowstone Supervolcano Has Just Seen 878 Earthquakes in Two Weeks” 

    ScienceAlert

    Science Alert

    29 JUN 2017
    CARLY CASSELLA

    1
    Suzi Pratt / shutterstock.com

    But don’t freak out just yet.

    Yellowstone has had a turbulent June. In just two weeks, the supervolcano that lies underneath the national park was hit with 878 earthquakes. The dense series of earthquakes, called an earthquake swarm, began on June 12. Within one week, the USGS had already recorded 464 earthquakes.

    “This is the highest number of earthquakes at Yellowstone within a single week in the past five years,” reported the USGS in a statement [U Utah] released last week.

    The majority of the earthquakes were no greater than a magnitude of 1, but the largest reached a magnitude of 4.4, which is the biggest earthquake experienced in Yellowstone since March 2014.

    But, thankfully, we don’t need to freak out anytime soon. It is extremely unlikely that these swarms will set off the supervolcano. In fact, the USGS sets the probability of the supervolcano erupting in the coming year at 1 in 730,000, and has kept its volcano alert level at green.

    “Swarms in Yellowstone are a common occurrence,” Jamie Farrell, a research professor at the University of Utah, which is part of the Yellowstone Volcano Observatory (YVO), told Newsweek.

    “On average, Yellowstone sees around 1,500-2,000 earthquakes per year. Of those, 40 to 50 percent occur as part of earthquake swarms.”

    And while the most recent swarm is larger than average, Farrell says there isn’t any evidence that the activity is related to magma moving in the subsurface.

    Geologists are constantly monitoring the Yellowstone supervolcano for unusual activity. If the volcano was about to blow, Farrell says they would start seeing increased seismicity, large changes in surface deformation, changes to the hydrothermal system and changes in gas output.

    “Typically if we see just one of these things, it doesn’t necessarily mean there is an eruption coming. If we start to see changes in all these things, then a red flag may be raised,” said Farrell.

    The Yellowstone supervolcano doesn’t blow very often. In the past two million years, it has only experienced three major eruptions.

    But even if it did erupt, Jacob Lowenstern, a scientist in charge of the YVO, says it would be fairly inconsequential.

    “If Yellowstone erupts, it’s most likely to be a lava flow, as occurred in nearly all the 80 eruptions since the last ‘supereruption’ 640,000 years ago,” he told Newsweek’s Hannah Osborne.

    “A lava flow would be a big deal at Yellowstone, but would have very little regional or continental effect.”

    Regardless, Farrell and the rest of the team at the University of Utah assure us they are continuing to monitor the swarm. So there won’t be any nasty surprises sneaking up out of Yellowstone anytime soon.

    See the full article here .

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  • richardmitnick 1:43 pm on January 4, 2017 Permalink | Reply
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    From AGU via EOS: “Pinpointing the Trigger Behind Yellowstone’s Last Supereruption” 

    Eos news bloc

    Eos

    AGU bloc

    AGU

    1.4.17
    Aylin Woodward
    aylin.y.woodward.gr@dartmouth.edu

    Geologists suggest that mixing of magma melt pockets could have caused the explosion a little more than 600,000 years ago.

    1
    View of the Grand Canyon of Yellowstone National Park. The canyon walls consist of rhyolitic tuff and lava. Crystals in such tuff may hold clues to magma conditions just prior to Yellowstone’s eruptions. Credit: Steven R. Brantley/USGS

    Yellowstone National Park is renowned for more than just its hot springs and Old Faithful. The area is famous in the volcanology community for being the site of three explosive supereruptions, the last of which was 631,000 years ago.

    2
    Map of the known ashfall boundaries for major eruptions from Yellowstone, with ashfall from the Long Valley Caldera and Mount St. Helens for comparison. Credit: USGS

    During that eruption, approximately 1000 cubic kilometers of rock, dust, and volcanic ash blasted into the sky. Debris rained across the continental United States, spanning a rough triangle that stretches from today’s Canadian border down to California and over to Louisiana. In places, ash reached more than a meter thick.

    “If something like this happened today, it would be catastrophic,” said Hannah Shamloo, a geologist at Arizona State University’s School of Earth and Space Exploration in Tempe. “We want to understand what triggers these eruptions, so we can set up warning systems. That’s the big-picture goal.”

    Now, Shamloo and her coauthor think they’ve found a clue. By examining trace elements in crystals that they found in the volcanic leftovers of Yellowstone’s last supereruption, they might be able to pinpoint what triggered it.

    Outer Rims

    Just outside Yellowstone National Park is a thick multicolored, multilayered rock formation called the Lava Creek Tuff. Tuffs are igneous rocks formed by the volcanic debris left behind by an explosive eruption.

    Minerals in these tuffs can tell scientists about conditions inside the volcano before it erupted, and identifying these preeruptive conditions may help inform current hazard assessments.

    3
    Arizona State University’s Christy Till points at an ash layer within the Lava Creek Tuff at the study site near Flagg Ranch, Wyo., just south of the Yellowstone boundary. Samples from this site are giving scientists information on what might have triggered Yellowstone’s most recent supereruption. Credit: Hannah Shamloo

    Shamloo and her Ph.D. adviser at Arizona State University, geologist Christy Till, examined two crystals of feldspar that they found embedded in the tuff. These crystals, called phenocrysts, form as magma cools slowly beneath the volcano.

    These phenocrysts, measuring between 1 and 2 millimeters in diameter, were too large to have formed when hot material was flung up during the eruption.

    Instead, as Shamloo explained, they grew gradually over time in Yellowstone’s magma chamber, each crystal beginning with a core that slowly and steadily enlarged outward, layer upon layer. As surrounding magma conditions—temperature, pressure, and water content— changed, trace elements surrounding the growing phenocrysts also changed and became incorporated into subsequent layers.

    In this way, the differences in chemical composition between the phenocryst core and successive layers serve as a map of changing conditions deep within the volcano over time. What’s more, the phenocrysts’ outermost rims represent the magma that surrounded the crystal right before Yellowstone erupted.

    Thus, by analyzing the outer rims, Shamloo and Till could gather both temperature and trace element information just prior to the massive explosion.

    Bubble, Bubble, Toil and Trouble

    5
    Feldspar phenocrysts from the Lava Creek Tuff. The outermost layers, which contain tiny bits of glass, are to the left. The phenocryst may be a fraction of a larger crystal that grew within the magma chamber or may have adhered to a different crystal on the right, explaining why layers are roughly vertical rather than concentric. Red represents the path of an electron microprobe, which cut through layers to collect chemical compositions. Credit: Hannah Shamloo

    Temperature information locked in a phenocryst’s outer rims can be extracted using a technique called feldspar thermometry. The technique relies on the fact that certain minerals vary their compositions in known ways as temperatures change. Thus, scientists can work backward from the exact compositions of minerals present in these outer rims to estimate the surrounding temperature when the crystal rim formed.

    The duo found signatures in the rims that point to an increase in temperature and uptick in the element barium in the magma just before the eruption. They presented their research on 13 December at the American Geophysical Union’s Fall Meeting in San Francisco, Calif.

    To verify their layer by layer analysis of temperature and chemical composition, Shamloo and Till used MELTS, a software program that models how the crystal composition changed as a function of temperature, pressure, and water content in the magma chamber. They assumed that the magma had the same bulk composition as the Lava Creek Tuff. Their results and the model agreed well but pointed to a low water content for the magma chamber involved in the recent supereruption. In contrast, an older eruption from Yellowstone that produced the Bishop Tuff had 5% water by weight, 5 times more than the one that produced the Lava Creek Tuff.

    The low water content is surprising, Shamloo explained, because water and steam create pressures that can trigger eruptions. But Shamloo said that the phenocrysts’ story of hotter temperatures and more barium in the magma chamber just prior to the eruption suggests a possible culprit behind the explosion: the mixing of neighboring pockets of semimelted magma, called an injection event. “There are multiple ways to trigger an eruption, but as of now, we’re seeing evidence for a magma injection,” she said.

    Magma, molten or semimolten rock that exists in layers of the Earth’s crust, can also reach the Earth’s surface. Because it is less dense than surrounding rocks, magma can move upward through cracks in the Earth’s crust, but when its motion is stymied, it pools into magma chambers. These chambers expand thanks to magma injections, when hotter material from deeper volcanic reservoirs feeds into shallower ones. This injection of hotter material just before the eruption may explain the temperature increase recorded in the phenocrysts.

    But the presence of barium in the phenocrysts is a smoking gun, said Shamloo. “Barium doesn’t like to be in the crystal. It likes to hang out in the melt, so this tells us the barium must’ve been introduced from a different source.” The duo thinks this source is a deeper reservoir inside the volcano.

    Eric Christiansen, a volcanologist from Brigham Young University in Provo, Utah, who was not involved with the study, was skeptical of Shamloo’s use of the MELTS software and thinks this type of modeling isn’t as reliable as “real experiments with real rocks.” However, he asserted, “her work is sound, and her analysis is solid. She’s got interesting trace element data with the barium, a late addition to the chamber, which suggests it accompanies what triggered the eruption.”

    Geologic Crystal Ball

    “The public is always afraid of the ‘next big one,’” Shamloo said. “And I like to ask, ‘Can we really forecast that?’” Shamloo and Till hope that they can.

    Knowing the eruption trigger is just the first step, according to Shamloo. The next step is understanding what order of time—days, months, even years—these changes can take before an eruption like the one that produced the Lava Creek Tuff.

    Such information could help Shamloo, Till, and others to correctly read signs of volcanic unrest at Yellowstone and to create a model for predicting future supereruptions.

    See the full article here .

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  • richardmitnick 2:22 pm on December 27, 2016 Permalink | Reply
    Tags: , , Supervolcanoes   

    From Science Alert: “The supervolcano that caused one of the biggest eruptions in history has started to stir” 

    ScienceAlert

    Science Alert

    22 DEC 2016
    BEC CREW

    1
    Donar Reiskoffer/Wikimedia

    It’s dangerously close to hitting a critical pressure point.

    A 12-km wide cauldron that forms a vast supervolcano on the coast of Italy is showing signs of reawakening after almost 500 years of inactivity.

    Not only is this site rumoured to be responsible for the extinction of the Neanderthals, it’s got 500,000 people living around it right now, and researchers say it appears to be approaching a critical pressure point that could lead to an eruption.

    A 12-km wide cauldron that forms a vast supervolcano on the coast of Italy is showing signs of reawakening after almost 500 years of inactivity.

    Not only is this site rumoured to be responsible for the extinction of the Neanderthals, it’s got 500,000 people living around it right now, and researchers say it appears to be approaching a critical pressure point that could lead to an eruption.

    Campi Flegrei – or “burning fields” in Italian – is another extensive volcanic area, located to the west of Naples, Italy.

    Boasting 24 craters and large volcanic edifices, mostly hidden under the Mediterranean Sea, this ancient ‘caldera’ – or cauldron-like depression – formed 39,000 years ago, as part of the biggest eruption Europe has seen in the past 200,000 years.

    Since its formation, Campi Flegrei has only had two major eruptions – 35,000 years ago and 12,000 years ago – and a smaller eruption that occurred in 1538.

    But when we say “smaller”, it’s all relative, because the 1538 eruption lasted for eight days straight, and spewed so much material into the surrounding area, it formed a new mountain, Monte Nuovo.

    It’s the whole site that’s a concern though – the eruption that occurred 200,000 years ago is thought to have been so cataclysmic, a 2010 study suggests that it triggered a ‘volcanic winter’, that ultimately led to the extinction of the Neanderthals.

    While the connection of the demise of the Neanderthals remains purely speculative until further evidence can be found, the eruption, which is thought to have spewed almost 1 trillion gallons (3.7 trillion litres) of molten rock onto the surface – along and with just as much sulphur into the atmosphere – is not.

    “These areas can give rise to the only eruptions that can have global catastrophic effects comparable to major meteorite impacts,” Giuseppe De Natale from Italy’s National Institute for Geophysics and Volcanology, told Reuters back in 2012.

    Now a team led by volcanologist Giovanni Chiodini from the Italian National Institute of Geophysics in Rome reports that Campi Flegrei appears to be approaching a critical pressure point that could trigger another eruption.

    This critical pressure point – referred to as critical degassing pressure (CDP) – could drive volcanic unrest towards a critical state, the team reports, by releasing jets of super-hot gas into the atmosphere, heating the surrounding hydrothermal fluids and rocks, and causing rock failure and possibly an eruption.

    “Hydrothermal rocks, if heated, can ultimately lose their mechanical resistance, causing an acceleration towards critical conditions,” Chiodini told the AFP.

    Over the past decade, Campi Flegrei has be experiencing an ‘uplift’, which suggests that the volatile gases beneath it are rising to the surface at an accelerating rate.

    In response to this uplift, Italy raised the supervolcano’s alert level from green to yellow – or from “quiet” to “requires scientific monitoring”.

    Two other active volcanoes, Rabaul in Papua New Guinea and Sierra Negra in the Galapagos, “both showed acceleration in ground deformation before eruption with a pattern similar to that observed at Campi Flegrei”, Chiodini said.

    So should the nearby residents panic? Not just yet, because at this stage, it’s pretty much impossible to predict what the Campi Flegrei caldera will do – if it does anything at all.

    “In general, unfortunately, volcanology is not a precise science,” Chiodini told Sarah Kaplan at The Washington Post.

    “We have many uncertainties and long-term previsions are at the moment not possible! For example, the process that we describe could evolve in both directions: toward pre-eruptive conditions or to the finish of the volcanic unrest.”

    The researchers are hoping that their latest observations of the supervolcano will urge more researchers to monitor the site in the coming years, because it looks like something is rumbling below – and we need to know just how bad it could get.

    The research has been published in Nature Communications.

    See the full article here .

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  • richardmitnick 12:29 pm on November 21, 2016 Permalink | Reply
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    From Science Alert: “We’re about to find out what’s rumbling below the Yellowstone Supervolcano” 

    ScienceAlert

    Science Alert

    16 NOV 2016
    BEC CREW

    1
    Grand Prismatic Spring, Yellowstone. Credit: Filip Fuxa/Shutterstock.com

    And what makes it so damn explosive.

    For the first time, scientists have started to map what lurks beneath the Yellowstone Supervolcano in Wyoming, so we can finally see the vast subterranean systems that fuel the famous Old Faithful geyser, and other hydrothermal vents at Yellowstone National Park.

    These maps will also allow us to better predict if and when a ‘super-eruption’ could occur in the area – something that hasn’t happened in 13,800 years, but when it did, it left behind the largest crater of its kind on the planet.

    “This is really kind of a last frontier if you will, in Yellowstone, of being able to look at a large part that’s underground that people have not looked at,” one of the team Carol Finn, from the US Geological Survey, told the media.

    “There’s just a lot we don’t know, and this survey is really exciting because it’s going to be the first view of a large portion of the groundwater system, of the water underground that feeds all of these thermal features.”

    You might imagine the Yellowstone Supervolcano as like a supersized volcano, rising up out of the ground and puffing whirls of menacing smoke from its gaping mouth, but in reality, it’s like a giant volcano that collapsed in on itself to form vast cauldron-like depressions.

    These depressions are called caldera, and they form when a volcano spews so much magma during an eruption, its now-empty chamber causes the whole thing to collapse like a massive sinkhole, leaving behind a massive crater.

    But it’s not like these craters have stopped exploding – the entire Yellowstone Supervolcano is like a vast volcanic field, covering an area of roughly 55 by 72 km (34 by 45 miles), where lava eruptions and swelling steam vents litter the otherworldly landscape.

    There have been three super-eruptions over the past couple of million years, with the Huckleberry Ridge eruption 2.1 million years ago; the Mesa Falls eruption 1.3 million years ago; and the Lava Creek eruption roughly 630,000 years ago.

    A smaller steam explosion around 13,800 years ago left behind a 5-km-diameter (3.1-mile) crater on the edge of Yellowstone Lake, which is thought to be the largest of its kind in the world.

    According to the Yellowstone National Park, 20 visitors have died due to minor explosions from the geothermal vents and hot spring – the most recent in 2000, when a tourist was scalded by boiling waters as hot as 121 degrees Celsius (250 degrees Fahrenheit).

    Needless to say, this is not a place that we want to be surprised by. It’s time we knew exactly what’s lurking below, so we can do a better job at predicting these explosions – large, small, and super.

    The new mapping project, which got underway on November 7, is starting with a helicopter electromagnetic and magnetic survey, which can sense even the tiniest voltages sparking underground.

    The helicopter is fitted with a giant, hoop-shaped electromagnetic system, which it suspends over the Yellowstone grounds by flying around 60 metres (200 feet) above the surface.

    Not only can this equipment detect subterranean electrical activity from above the surface, it also acts like a giant X-ray machine, detecting the shapes and behaviour of things like geysers, hot springs, mud pots, steam vents, and hydrothermal explosion craters to depths of up to 500 metres (1,500 feet).

    It will also be able to detect where and how hot water flows beneath the surface.

    “Nobody knows anything about the flow paths” of hot water that erupts from Yellowstone’s geysers, Finn told the Associated Press. “Does it travel down and back up? Does it travel laterally?”

    What we do know, thanks to study carried out last year, is that there’s way more magma below Yellowstone than anyone had imagined, with researchers detecting a second reservoir of hot, partly molten rock underneath the more shallow magma chamber we already knew about.

    As we reported back in April 2015, this vast reservoir lies some 20-45 kilometres (12-27 miles) beneath the supervolcano, and this new chamber could fill the Grand Canyon up 11.2 times.

    And we don’t want any of that fuelling a calderic eruption without some kind of warning first, as Sarah Kaplan reports for The Washington Post:

    “A calderic eruption, in which that magma came rushing to the surface, would eject 1,000 times more material than the 1980 eruption of Mount St. Helens [the deadliest eruption in US history], and could create a caldera dozens of miles wide.

    The last time this happened, 640,000 years ago, Homo sapiens didn’t even exist yet. No one is certain what causes such an eruption, or when the Yellowstone supervolcano might erupt again.”

    The mapping survey is being run by the US Geological Survey, the University of Wyoming, and the Aarhus University in Denmark. It’s expected to take four weeks, and it will inform future ground-based surveys around the volcanic hotspot.

    We seriously cannot wait to see what they find.

    See the full article here .

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  • richardmitnick 11:41 am on September 17, 2016 Permalink | Reply
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    From Science Vibe: “Yellowstone Sits On Restless Volatile Supervolcano! The World’s Biggest? [ includes video]” 

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    SCIENCE VIBE

    February 16, 2016
    No writer credit

    1
    http://io9.gizmodo.com/what-will-really-happen-when-yellowstone-volcano-has-a-508274690

    There is a giant Supervolcano sitting underneath Yellowstone and scientists say it will erupt again and that the only real question is “when”, and not “if”. There are three things that indicate an imminent volcano eruption: 1) earthquakes, 2) land deformation, and 3) changes in thermal activity like an increase in geyser activity and higher water temperatures. Scientist say that all three indicators are present at Yellowstone.

    The Yellowstone Plateau is a ‘geomorphic landform’ and the is no question that one day the restless giant will awakened and erupt into a massive explosion. Magma which is molten rock from the Earth’s mantle has been near the surface for almost 2 million years making extremely volatile. The resurgent domes inside the Yellowstone Caldera and magma may be as little as 3–8 miles beneath Sour Creek Dome and 8–12 miles beneath at Mallard Lake Dome. The domes lift and subside when magma activity and hydrothermal fluids swell up or drop down and the frequency indicates just how volatile the this Supervolcano truly is.

    When the first massive volcanic eruption occurred eons ago the volume of material ejected was approximately 6,000 times the size of the 1980 eruption of Mt. St. Helens in Washington. Approximately 1.3 million years ago, a second, smaller volcanic eruption occurred within the western edge and then 640,000 years ago, a third massive volcanic eruption created the Yellowstone Caldera, 30 by 45 miles in size.

    This Supervolcano could become the biggest eruption in history!

    See the full article here .

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  • richardmitnick 8:59 am on August 7, 2016 Permalink | Reply
    Tags: , , Supervolcanoes,   

    From EarthSky: “How much warning for supervolcanoes?” 

    1

    EarthSky

    July 28, 2016
    Eleanor Imster

    1
    Image via National Park Service

    Yellowstone supervolcano could deposit ash across the U.S. Northwest, clogging rivers and streams and affecting agriculture. How much advance warning might we have?

    1
    National Park Service

    3
    An example of the possible distribution of ash from a month-long Yellowstone supereruption. (US Geological Survey)

    A new analysis of quartz crystals from the site of a supervolcano that erupted 760,000 years ago suggest that supervolcanoes might give us about a year’s warning before they blow. That’s according to a study by scientists at Vanderbilt University in Nashville, Tennessee, published July 20, 2016 in the journal PLOS One.

    What’s a supervolcano,and what happens if one erupts? According to the U.S. Geological Survey:

    A supervolcano is a volcano that at one point in time erupted more than 1,000 cubic kilometers [240 cubic miles] of deposits.

    That’s about enough material to fill up Lake Erie twice. Notice they’re speaking of “deposits” – in other words, ash – here. It’s ash that’s the main issue with supervolcanoes. For example, studies of the supervocano under Yellowstone National Park suggest the lava from past eruptions never traveled much farther than the park boundaries. The ash would go farther, spreading across an area about 500 miles (800 km) across surrounding Yellowstone (Denver, Colorado, for example, is about 500 miles from Yellowstone). Studies suggest the region inside this circle might see more than 4 inches (10 cm) of ash on the ground. A larger area in the central U.S. would see a shallower covering of ash, which would still clog rivers and streams and affect agriculture.

    How much warning would we have for such an eruption? The new Vanderbilt study, suggesting a year of advance warning, is based on the idea that – before a super volcano erupts – a huge amount of magma needs to build up. The build-up takes tens of thousands of years, said study author Guilherme Gualda, but, once established, these giant magma bodies are unstable features that last for only centuries to few millennia. Gualda said in a statement:

    “We have shown that the onset of the process of decompression, which releases the gas bubbles that power the eruption, starts less than a year before eruption.”

    3
    Long Valley Caldera in eastern California was created by a supervolcano eruption 760,000 years ago. Image via NASA/JPL.

    These scientists studied microscopic quartz crystals in pumice taken from the Bishop Tuff in eastern California, which is the site of the super-eruption that formed the Long Valley Caldera 760,000 years ago. The researchers analyzed how long it took distinctive surface rims on the crystals to grow, a factor that previous studies have suggested are indicative of the lead time before a super volcano erupts. The new study determined that over 70 percent of the rim growth times were shorter than one year. The paper summarized:

    Maximum rim growth times span from approximately 1 minute to 35 years, with a median of approximately 4 days. More than 70 percent of rim growth times are less than 1 year, showing that quartz rims have mostly grown in the days to months prior to eruption.

    The study suggests that intensifying signs of an impending super-eruption would start to be felt within a year of eruption, but scientists aren’t sure what exactly the signs at the surface would be.

    The study suggests that intensifying signs of an impending super-eruption would start to be felt within a year of eruption, but scientists aren’t sure what exactly the signs at the surface would be.

    Here are a few of the very large eruptions – including super-eruptions – that have happened in the recent geological past:

    Oruanui eruption, 26,500 years ago. The Taupo Volcanic Zone in New Zealand is the site of this most recent super-eruption. It also includes deposits from more than a dozen very large eruptions that happened within in the last couple of million years.

    Campi Flegrei eruption in Italy, 40,000 years ago.

    Toba eruption in Sumatra 75,000 years ago.

    – Yellowstone in the United States has experienced three super-eruptions over the last two million years.

    Gualda said it seems inevitable that another super-eruption will strike the Earth in the future. But, he said:

    “As far as we can determine, none of these places currently house the type of melt-rich, giant magma body needed to produce a super-eruption. However, they are places where super-eruptions have happened in the past so are more likely to happen in the future.”

    Bottom line: A new study suggest that supervolcanoes give about a year’s warning before they blow.

    See the full article here .

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  • richardmitnick 9:58 am on July 22, 2016 Permalink | Reply
    Tags: , , Supervolcanoes, We’ll Only Have a Year to Prepare For a Cataclysmic Super-Eruption   

    From GIZMODO: “We’ll Only Have a Year to Prepare For a Cataclysmic Super-Eruption” 

    GIZMODO bloc

    GIZMODO

    7.21.16
    George Dvorsky

    1
    Image: GFZ German Research Centre for Geosciences

    Volcanic super-eruptions are bad. Like really bad. Scientists warn of such a potentially civilization-ending catastrophe in our future, but as a new study shows, we’ll only have a year to prepare once the signs of an impending eruption become visible.

    A new microscopic analysis of quartz crystals taken from the site of a massive volcanic eruption that occurred 760,000 years ago in eastern California suggests we’ll only have about a year’s worth of advance warning before a devastating super-eruption. In a paper published in PLOS ONE, Guilherme Gualda from Vanderbilt University and Stephen Sutton from the University of Chicago show that super-eruptions don’t require much time to blow their tops, even though they’re tens of thousands of years in the making.

    2
    The Long Valley Caldera in eastern California, the result of a super-eruption 760,000 years ago. (Image: NASA/JPL)

    Unlike “conventional” eruptions, these explosions are among the most devastating on the planet, unleashing destruction that can flatten continents, trigger new ice ages, and potentially put an end to human civilization as we know it. They happen when the magma in the mantle rises into the crust, but is unable to breach the surface. The ensuing pressure builds and builds in an ever-growing magma pool until the crust can no longer contain the pressure. The results of the ensuing explosion are nothing short of catastrophic. In the most severe cases, a supervolcano can eject upwards of 1,000 cubic kilometers of ash into the sky.

    Our planet has experienced several super-eruptions in the recent geological past. The Taupo Volcanic Zone in New Zealand erupted 26,500 years ago, and Campi Flegrei in Italy erupted 40,000 years ago. Other noteable super-eruptions include Indonesia’s Toba super-eruption in Sumatra 75,000 years ago and the Tambora eruption in 1815. Wyoming’s Yellowstone has super-erupted three times in the past million years, and there’s fear it could happen again. As these episodes show, super-eruptions are still a part of Earth’s geological fabric. It’s not a matter of if they’ll happen again, but when.

    As these timelines suggest, super-eruptions evolve over relatively long timescales. But as the new study by Gualda and Sutton shows, the final stage doesn’t take very long at all.

    “The evolution of a giant, super-eruption-feeding magma body is characterized by events taking place at a variety of time scales,” noted Gualda in a release. It typically takes tens of thousands of years to “prime” the crust with the requisite amounts of magma. Once these pools are established, the giant magma bodies swell and fester for a few millennia or even just a few centuries. “Now we have shown that the onset of the process of decompression, which releases the gas bubbles that power the eruption, starts less than a year before eruption,” said Gualda.

    3
    A quartz crystals used in the analysis. (Image: Guilherme Gualda/Vanderbilt University)

    Gualda and Sutton reached this conclusion by analyzing small quartz crystals in pumice taken from the site of the Long Valley Caldera that formed nearly a million years ago. This allowed the researchers to measure the distinctive surface rims found at the sites of super-eruptions. By measuring the size and growth rates of these rims, the researchers were able to determine the length of time it took for an explosion to happen once the collapse phase begins. Analysis showed that more than 70 percent of rim growth times were less than a year, indicating that quartz rims mostly grow in the days and months prior to an eruption.

    According to the researchers, we’ll likely be able to detect the signs of a pending super-eruption by noticing the bloating effects of the expanding magma body on the surface. More work is needed to know more about these warning signs, but this new study suggests that these signals will start to appear within a year of an eruption. And they’ll intensify as the explosion gets closer.

    See the full article here .

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  • richardmitnick 6:45 am on July 20, 2016 Permalink | Reply
    Tags: , , Supervolcanoes   

    From COSMOS: “Why supervolcanoes erupt with cataclysmic explosions” 

    Cosmos Magazine bloc

    COSMOS

    20 July 2016
    Belinda Smith

    1
    Russian geophysicist and artist Ivan Koulakov and colleagues have modelled magma reservoirs beneath supervolcanoes. Here is Koulakov’s impression of the Earth’s magmatic plumbing. Ivan Koulakov

    Lake Toba in North Sumatra today is a calm 100-kilometre stretch of water, flanked by green hills and rocky outcrops.

    But a mere 74,000 years ago, the region couldn’t have been more different: the supervolcano that forms the lake’s bowl blasted up to 5,300 square kilometres of hot rock and dust into the atmosphere and surface, leading to a volcanic winter which dropped global temperatures by 3 to 5 ºC for the best part of a decade.

    There’s no doubt these supereruptions are capable of widespread destruction.

    Some scientists believe the “Toba catastrophe” killed off most humans. And Toba today is one of many supervolcanoes scattered across the globe.

    To better understand why supervolcanoes erupt majestically then sit quiet for hundreds of thousands of years, rather than burble along at a moderate rate, a team from Egypt, France, Russia and Saudi Arabia delved into Toba’s plumbing and found it’s fed by a massive magma reservoir that gradually builds up over millennia before exploding.

    Russian Academy of Sciences Ivan Koulakov and colleagues examined how waves from earthquakes shook the region in 1995 and 2008.

    In particular, they looked at P-waves – which can course through liquid as well as rock and are the first waves of an earthquake to show up on a seismograph – and S-waves, which can only move through solids.

    From these they determined the complex, multi-level structure of the Earth 150 kilometres beneath the Toba caldera and movements of rock and volatiles such as water.

    The “magma factory” starts with the Indo-Australian plate, which is sliding underneath Indonesia at around 56 millimetres each year. It’s torn, too – one end is denser, and sinking faster, than the other end. The tear is known as the Investigator Fracture Zone and runs underneath the Toba caldera.

    At around 150 kilometres below the surface on the frature zone, the plate melts. Volatiles escape the rock to burble up through the mantle and fill a magma reservoir of around 50,000 square kilometres, which sits 30 to 50 kilometres below Lake Toba.

    The magma in the chamber is too dense to make its way any further and the overlying crust hems it in. But as more volatiles rise and join the reservoir, bringing heat with them, they cause more rocks to melt.

    When the molten upper crust is saturated with these volatiles, they cause what the researchers call an “avalanche-style process”. Overheated fluids turn to gases, increasing pressure in the reservoir and bam! The contents empty in a massive eruption.

    The process, then, begins again. It will repeat until the fracture zone is completely subducted.

    So is there going to be another Toba super-explosion soon? Koulakov thinks not – the next will happen in the next tens or hundreds of thousands of years. They found S-waves managed to move through the magma reservoir, signifying a large chunk of solid rock. If it was liquid, though, the next explosion would happen much sooner.

    The work was published in Nature Communications.

    See the full article here .

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  • richardmitnick 8:39 pm on May 15, 2016 Permalink | Reply
    Tags: , , Supervolcanoes,   

    From livescience: “What Would Happen If Yellowstone’s Supervolcano Erupted?” 

    Livescience

    May 2, 2016
    Becky Oskin

    1
    Hot springs in Yellowstone National Park are just one of the types of thermal features that result from volcanic activity. Credit: Dolce Vita / Shutterstock.com

    Although fears of a Yellowstone volcanic blast go viral every few years, there are better things to worry about than a catastrophic supereruption exploding from the bowels of Yellowstone National Park.

    Caldera at Yellowstone  Image not credited
    Caldera at Yellowstone Image not credited

    Scientists at the U.S. Geological Survey’s (USGS) Yellowstone Volcano Observatory always pooh-pooh these worrisome memes, but that doesn’t mean researchers are ignoring the possible consequences of a supereruption. Along with forecasting the damage, scientists constantly monitor the region for signs of molten rock tunneling underground. Scientists scrutinize past supereruptions, as well as smaller volcanic blasts, to predict what would happen if the Yellowstone Volcano did blow. Here’s a deeper look at whether Yellowstone’s volcano would fire up a global catastrophe.

    Probing Yellowstone’s past Most of Yellowstone National Park sits inside three overlapping calderas. The shallow, bowl-shaped depressions formed when an underground magma chamber erupted at Yellowstone. Each time, so much material spewed out that the ground collapsed downward, creating a caldera. The massive blasts struck 2.1 million, 1.3 million and 640,000 years ago. These past eruptions serve as clues to understanding what would happen if there was another Yellowstone megaexplosion.

    2
    An example of the possible ashfall from a month-long Yellowstone supereruption. Credit: USGS –

    If a future supereruption resembles its predecessors, then flowing lava won’t be much of a threat. The older Yellowstone lava flows never traveled much farther than the park boundaries, according to the USGS. For volcanologists, the biggest worry is wind-flung ash. Imagine a circle about 500 miles (800 kilometers) across surrounding Yellowstone; studies suggest the region inside this circle might see more than 4 inches (10 centimeters) of ash on the ground, scientists reported* Aug. 27, 2014, in the journal Geochemistry, Geophysics, Geosystems.

    The ash would be pretty devastating for the United States, scientists predict. The fallout would include short-term destruction of Midwest agriculture, and rivers and streams would be clogged by gray muck. People living in the Pacific Northwest might also be choking on Yellowstone’s fallout. “People who live upwind from eruptions need to be concerned about the big ones,” said Larry Mastin, a USGS volcanologist and lead author of the 2014 ash study. Big eruptions often spawn giant umbrella clouds that push ash upwind across half the continent, Mastin said. These clouds get their name because the broad, flat cloud hovering over the volcano resembles an umbrella. “An umbrella cloud fundamentally changes how ash is distributed,” Mastin said. But California and Florida, which grow most of the country’s fruits and vegetables, would see only a dusting of ash. A smelly climate shift.

    Yellowstone Volcano’s next supereruption is likely to spew vast quantities of gases such as sulfur dioxide, which forms a sulfur aerosol that absorbs sunlight and reflects some of it back to space. The resulting climate cooling could last up to a decade. The temporary climate shift could alter rainfall patterns, and, along with severe frosts, cause widespread crop losses and famine.

    3
    The walls of the Grand Canyon of Yellowstone are made up predominantly of lava and rocks from a supereruption some 500,000 years ago. Credit: USGS

    But a Yellowstone megablast would not wipe out life on Earth. There were no extinctions after its last three enormous eruptions, nor have other supereruptions triggered extinctions in the last few million years.

    “Are we all going to die if Yellowstone erupts? Almost certainly the answer is no,” said Jamie Farrell, a Yellowstone expert and assistant research professor at the University of Utah. “There have been quite a few supereruptions in the past couple million years, and we’re still around.” However, scientists agree there is still much to learn about the global effects of supereruptions. The problem is that these massive outbursts are rare, striking somewhere on Earth only once or twice every million years, one study found. “We know from the geologic evidence that these were huge eruptions, but most of them occurred long enough in the past that we don’t have much detail on what their consequences were,” Mastin said. “These events have been so infrequent that our advice has been not to worry about it.” A far more likely damage scenario comes from the less predictable hazards — large earthquakes and hydrothermal blasts in the areas where tourists roam. “These pose a huge hazard and could have a huge impact on people,” Farrell said.

    Supereruption reports are exaggerated

    Human civilization will surely survive a supereruption, so let’s bust another myth. There is no pool of molten rock churning beneath Yellowstone’s iconic geysers and mud pots. The Earth’s crust and mantle beneath Yellowstone are indeed hot, but they are mostly solid, with small pockets of molten rock scattered throughout, like water inside a sponge. About 9 percent of the hot blob is molten, and the rest is solid, scientists reported on May 15, 2015, in the journal Science. This magma chamber rests between 3 to 6 miles (5 to 10 km) beneath the park. Estimates vary, but a magma chamber may need to reach about 50 percent melt before molten rock collects and forces its way out. “It doesn’t look like at this point that the [Yellowstone] magma reservoir is ready for an eruption,” said Farrell, co-author of the 2015 study in the journal Science.

    How do researchers measure the magma? Seismic waves travel more slowly through hot or partially molten rock than they do through normal rock, so scientists can see where the magma is stored, and how much is there, by mapping out where seismic waves travel more slowly, Farrell said.

    The magma storage region is not growing in size, either, at least for as long as scientists have monitored the park’s underground. “It’s always been this size, it’s just we’re getting better at seeing it,” Farrell said.

    Watch out for little eruptions

    As with magma mapping, the science of forecasting volcanic eruptions is always improving. Most scientists think that magma buildup would be detectable for weeks, maybe years, preceding a major Yellowstone eruption. Warning signs would include distinctive earthquake swarms, gas emissions and rapid ground deformation.

    Someone who knows about these warning signals might look at the park today and think, “Whoa, something weird is going on!” Yellowstone is a living volcano, and there are always small earthquakes causing tremors, and gas seeping from the ground. The volcano even breathes — the ground surface swells and sinks as gases and fluids move around the volcanic “plumbing” system beneath the park.

    But the day-to-day shaking in the park does not portend doom. The Yellowstone Volcano Observatory has never seen warning signs of an impending eruption at the park, according to the USGS.

    What are scientists looking for? For one, the distinctive earthquakes triggered by moving molten rock. Magma tunneling underground sets off seismic signals that are different from those generated by slipping fault lines. “We would see earthquakes moving in a pattern and getting shallower and shallower,” Farrell said. To learn about the earthquake patterns to look for, revisit the 2014 eruption of Bardarbunga Volcano in Iceland. Both amateurs and experts “watched” Bardarbunga’s magma rise underground by tracking earthquakes. The eventual surface breakthrough was almost immediately announced on Twitter and other social media. As with Iceland, all of Yellowstone’s seismic data is publicly available through the U.S. Geological Survey’s Yellowstone Volcano Observatory and the University of Utah.

    “We would have a good idea that magma is moving up into the shallow depths,” Farrell said.

    “The bottom line is, we don’t know when or if it will erupt again, but we would have adequate warning.”

    *Science paper:
    Modeling ash fall distribution from a Yellowstone supereruption

    See the full article here .

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  • richardmitnick 9:19 pm on April 15, 2016 Permalink | Reply
    Tags: , , Supervolcanoes   

    From New Scientist: “Waking supervolcano makes North Korea and West join forces” 

    NewScientist

    New Scientist

    15 April 2016
    Andy Coghlan

    1
    The crater atop Mount Paektu. Raymond Cunningham/Getty

    If it blows again, it could make Vesuvius look like a tea party.

    Now, in a ground-breaking collaboration between the West and North Korea, vulcanologists are gaining new insights into Mount Paektu, on North Korea’s border with China, and whether it might blow its top any time soon.

    If it does, the outcome could be catastrophic. Paektu’s last eruption, a thousand years ago, is the second largest ever recorded, topped only by the eruption of Mount Tambora in Indonesia in 1815.

    “If it erupted, it would have impacts way beyond Korea and China,” says James Hammond of Birkbeck, University of London, one of the scientists involved.

    In 946 AD, the eruption of Mount Paektu, Korea’s highest mountain, blasted 96 cubic kilometres of debris into the sky, 30 times more than the relatively puny 3.3 cubic kilometres that Vesuvius spewed over Pompeii in AD 79.

    Yet despite is size and the potential impact of an eruption, little is known about this enigmatic volcano.

    Growing fears

    Western researchers got involved because the team investigating the volcano in North Korea, led by Ri Kyong-Song of the government’s Earthquake Administration in Pyongyang, needed access to extra scientific equipment and know-how.

    Chinese vulcanologists, who have been monitoring the volcano they call Changbaishan from their side of the border, also wanted more information from the Korean side.

    They and the Koreans have been monitoring the volcano closely ever since suspicious bulges were seen in and around the volcano between 2002 and 2005. These involved ground deformations measured by GPS, increased gas emissions and seismic rumbles.

    “It’s a priority for both countries, and both have monitoring networks on the volcano, keeping an eye on it,” says Hammond.

    Hammond and others from the West were invited to Korea in 2011 to install six seismometers at distances up to 60 kilometres from the volcano. These were sited to detect seismic waves from earthquakes elsewhere in the world passing through the ground beneath Paektu.

    Seismic waves travel at different speeds through solid and molten rock, giving the researchers crucial information about what lies beneath.

    The results reveal that there is indeed extensive magma beneath the volcano. “It’s a mushy mixture of molten rock and crystals that goes down right through the crust around 35 kilometres deep,” says Hammond.

    It’s rare to see a partially melted type of magma with such a large fluid component throughout the whole crust, he says.

    These are the first known estimates of the crustal structure of the volcano’s North Korea side and for anywhere beneath North Korea.

    The partially melted crust is a potential source for magma in past eruptions and it may be associated with the recent volcanic unrest there.

    At the moment, though, there’s no pool of liquid magma gathering near the surface – often a prelude to an eruption.

    “One of the challenges now is to go beyond simply saying there’s magma in the crust, discovering instead how it’s sitting, how much there is and what are the implications,” says Hammond. “It’s only when it gets to a certain amount and a certain overpressure that it will erupt.”

    At present, the researchers are not sure how much has to accumulate before the volcano erupts, he says.

    That’s why the collaboration is set to continue for some time, with Hammond due back in Pyongyang next week. “We’ll be discussing what we’ll do over the next 12 months, and longer term over the next five to 10 years,” says Hammond.

    After years working together, the two teams have got to know each other well, talking geology through an interpreter during the day, and in the evening heading for a restaurant or karaoke bar.
    No politics, just science

    “With what we’re doing, there’s no political element – we’re involved to understand a huge volcano, and the fact we’re having this dialogue is a great example of science transcending political differences,” says Hammond.

    Ri also spent a month in the UK finalising the results and the draft for publication*. “Our project is an example that it’s possible to build these collaborations and establish mutual trust,” says Hammond. “It’s been an advantage that our science doesn’t come with much political baggage.”

    North Korea is keen to open doors for more scientists through an institution called Piintec, Hammond says. “The Koreans are very open to science engagement in most areas.”

    “This is a bit of a first, in terms of a collaboration resulting in publication in a high-profile Western journal,” says Hammond.

    So next week, when he reaches Pyongyang, he and his Korean colleagues will be celebrating, probably in a karaoke bar in Pyongyang, drinking soju, the rice liquor popular in the country.

    “We get on very well,” says Hammond. “That’s why it works, through relationships and trust, and for that to work you need to understand each other.”

    Journal reference: Science Advances, DOI: 10.1126/sciadv.1501513

    *Science paper:
    Evidence for partial melt in the crust beneath Mt. Paektu (Changbaishan), Democratic People’s Republic of Korea and China

    Science team:
    Ri Kyong-Song1, James O. S. Hammond2,*, Ko Chol-Nam1, Kim Hyok1, Yun Yong-Gun1, Pak Gil-Jong1, Ri Chong-Song1, Clive Oppenheimer3, Kosima W. Liu4, Kayla Iacovino5 and Ryu Kum-Ran6

    Affiliations
    1Earthquake Administration, Pyongyang, Democratic People’s Republic of Korea.
    2Department of Earth and Planetary Sciences, Birkbeck College, University of London, London WC1E 7HX, UK.
    3Department of Geography, University of Cambridge, Cambridge CB2 3EN, UK.
    4Environmental Education Media Project, Beijing 100025, China.
    5U.S. Geological Survey, Menlo Park, CA 94025, USA.
    6Pyongyang International Information Centre of New Technology and Economy, Pyongyang, Democratic People’s Republic of Korea.

    ↵*Corresponding author. E-mail: j.hammond@ucl.ac.uk

    See the full article here .

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