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

    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
    Tags: , , , , , Yellowstone   

    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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    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 11:41 am on September 17, 2016 Permalink | Reply
    Tags: , , , Yellowstone   

    From Science Vibe: “Yellowstone Sits On Restless Volatile Supervolcano! The World’s Biggest? [ includes video]” 

    Science Vibe bloc

    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: , , , Yellowstone   

    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 5:52 pm on March 28, 2016 Permalink | Reply
    Tags: , , Yellowstone   

    From livescience: “12 Supereruptions Pockmark Path of Yellowstone Hotspot” 

    Livescience

    March 28, 2016
    Becky Oskin

    Caldera at Yellowstone
    Caldera at Yellowstone. Image not credited

    Up to 12 massive volcanic blasts occurred between 8 million and 12 million years ago in Idaho’s Snake River Plain, leading up to today’s Yellowstone supervolcano, new research reveals.

    A dozen of these ancient supereruptions took place along the Yellowstone hotspot track, researchers reported Feb. 10 in the journal Geological Society of America Bulletin. The trail of eruptions marks where the North American tectonic plate sailed over a superhot blob of mantle rock called a hotspot. (The mantle is the rocky layer between Earth’s crust and core.)

    Though learning of more supereruptions in the West may seem unsettling, the findings do not suggest that Yellowstone today is any more hazardous than previously suspected. Instead, the researchers said they are now studying whether Yellowstone is actually dwindling in strength compared to the larger and more violent eruptions that occurred 12 million years ago.

    “While it is well-known that Yellowstone has erupted catastrophically in recent times, perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic supereruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone,” lead study author Tom Knott, a geochemist at the University of Leicester in the United Kingdom, said in a statement.

    The rainbow-colored hot springs and high-flying geysers at Yellowstone National Park in Wyoming are fed by an underground reservoir of molten rock. The park formed in a series of eruptions during the past 2 million years. Powerful explosions 640,000 years ago created a giant crater and spewed ash as far as New York. The most recent eruption occurred about 70,000 years ago.

    Until now, geologists did not have a firm count of the number of eruptions in Idaho and surrounding states that predate Yellowstone, nor a good estimate of the size of each outburst. The new study suggests there are fewer volcanic eruptions in the central Snake River Plain than previously believed. However, the 12 recorded giant eruptions were likely “significantly larger” than other studies suggested, the researchers said.

    The craters formed by these giant eruptions are now buried under sediment and younger lava flows. To better understand past eruptions, Knott led an international team of volcano experts in analyzing the many layers of lava plating central Idaho. The researchers fingerprinted different eruptions by testing for changes in the chemical makeup of the rocks and the rocks’ magnetic orientation. (Every volcanic eruption produces lava with a unique chemical makeup.) The team correlated these volcanic deposits across hundreds of miles (thousands of kilometers).

    With the new correlations, the team reduced the number of eruptions thought to have originated from the central Snake River Plain by more than half. The research also revealed that these eruptions were significantly larger than suspected, and may have rivaled those at Yellowstone.

    Hotspots seem to stay in one place while the Earth’s crust trundles over them. The crustal movement creates a line of volcanoes, like the crumbs left behind by a fairytale Hansel and Gretel. The Hawaiian islands and Emperor Seamounts are textbook examples of hotspot volcanism.

    One of the supereruptions from the Yellowstone hotspot track, called the Castleford Crossing eruption, now covers an area more than 5,400 square miles (14,000 square km) in southern Idaho, and is more than 4,200 feet (1.3 km) thick in the caldera of the Castleford Crossing supervolcano. The eruption was likely 10 times as powerful as Mount St. Helens’ 1980 blast, the study reported.

    “The size and magnitude of this newly defined eruption is as large as, if not larger than better-known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered supereruptions during a period of intense magmatic activity between 8 [million] and 12 million years ago,” Knott said.

    See the full article here .

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