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  • richardmitnick 6:50 am on July 28, 2018 Permalink | Reply
    Tags: , , VT, Yellowstone supervolcano   

    From Virginia Tech: “Virginia Tech scientist: Yellowstone super-volcano eruptions were produced by gigantic ancient oceanic plate” 

    Virginia Tech

    July 20, 2018

    Contact:
    Steven Mackay
    540-231-5035

    1
    Location of the Yellowstone’s hotspot track. The triangles indicate general locations of the Yellowstone and Snake River Plain age-progressive volcanoes with ages shown in millions of years, plotted on a topography map of the Western United States.

    The long-dormant Yellowstone super-volcano in the American West has a different history than previously thought, according to a new study [Nature Geoscience] by a Virginia Tech geoscientist.

    Scientists have long thought that Yellowstone Caldera, part of the Rocky Mountains and located mostly in Wyoming, is powered by heat from the Earth’s core, similar to most volcanoes such as the recently active Kilauea volcano in Hawaii. However, new research published in Nature Geoscience by Ying Zhou, an associate professor with the Virginia Tech College of Science’s Department of Geosciences, shows a different past.

    “In this research, there was no evidence of heat coming directly up from the Earth’s core to power the surface volcano at Yellowstone,” Zhou said. “Instead, the underground images we captured suggest that Yellowstone volcanoes were produced by a gigantic ancient oceanic plate that dove under the Western United States about 30 million years ago. This ancient oceanic plate broke into pieces, resulting in perturbations of unusual rocks in the mantle which led to volcanic eruptions in the past 16 million years.”

    The eruptions were very explosive, Zhou added. A theoretical seismologist, Zhou created X-ray-like images of the Earth’s deep interior from USArray – part of the Earthscope project funded by the National Science Foundation – and discovered an anomalous underground structure at a depth of about 250 to 400 miles right beneath the line of volcanoes.

    “This evidence was in direct contradiction to the plume model,” Zhou said.

    In her study, Zhou found the new images of the Earth’s deep interior showed that the oceanic Farallon plate, which used to be where the Pacific Ocean is now, wedged itself beneath the present-day Western United States. The ancient oceanic plate was broken into pieces just like the seafloor in the Pacific today. A section of the subducted oceanic plate started tearing off and sinking down to the deep earth.

    The sinking section of oceanic plate slowly pushed hot materials upward to form the volcanoes that now make up Yellowstone. Further, the series of volcanoes that make up Yellowstone have been slowly moving,
    achingly so, ever since. “The process started at the Oregon-Idaho border about 16 million years ago and propagated northeastward, forming a line of volcanoes that are progressively younger as they stretched northeast to present-day Wyoming,” Zhou added.

    The previously-held plume model was used to explain the unique Yellowstone hotspot track – the line of volcanoes in Oregon, Idaho, and Wyoming that dots part of the Midwest. “If the North American plate was moving slowly over a position-fixed plume at Yellowstone, it will displace older volcanoes towards the Oregon-Idaho border and form a line of volcanoes, but such a deep plume has not been found.” Zhou said. So, what caused the track? Zhou intends to find out.

    “It has always been a problem there, and scientists have tried to come up with different ways to explain the cause of Yellowstone volcanoes, but it has been unsuccessful,” she said, adding that hotspot tracks are more popular in oceans, such as the Hawaii islands. The frequent Geyser eruptions at Yellowstone are of course not volcanic eruptions with magna, but due to super-heated water. The last Yellowstone super eruption was about 630,000 years ago, according to experts. Zhou has no predictions on when or if Yellowstone could erupt again.

    The use of the X-ray-like images for this study is unique in itself. Just as humans can see objects in a room when a light is on, Zhou said seismometers can see structures deep within the earth when an earthquake occurs. The vibrations spread out and create waves when they hit rocks. The waves are detected by seismometers and used in what is known as diffraction tomography.

    “This is the first time the new imaging theory has been applied to this type of seismic data, which allowed us to see anomalous structures in the Earth’s mantle that would otherwise not be resolvable using traditional methods,” Zhou said.

    Zhou will continue her study of Yellowstone. “The next step will be to increase the resolution of the X-ray-like images of the underground rock,” she added.

    “More detailed images of the unusual rocks in the deep earth will allow us to use computer simulation to recreate the fragmentation of the gigantic oceanic plate and test different scenarios of how rock melting and magma feeding system work for the Yellowstone volcanoes.”

    See the full article here .

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    Virginia Polytechnic Institute and State University, commonly known as Virginia Tech and by the initialisms VT and VPI,[8] is an American public, land-grant, research university with a main campus in Blacksburg, Virginia, educational facilities in six regions statewide, and a study-abroad site in Lugano, Switzerland. Through its Corps of Cadets ROTC program, Virginia Tech is also designated as one of six senior military colleges in the United States.

    As Virginia’s third-largest university, Virginia Tech offers 225 undergraduate and graduate degree programs to some 30,600 students and manages a research portfolio of $513 million, the largest of any university in Virginia.[9] The university fulfills its land-grant mission of transforming knowledge to practice through technological leadership and by fueling economic growth and job creation locally, regionally, and across Virginia.

    Virginia Polytechnic Institute and State University officially opened on Oct. 1, 1872, as Virginia’s white land-grant institution (Hampton Normal and Industrial Institute, founded in 1868, was designated the commonwealth’s first black land-grant school. This continued until 1920, when the funds were shifted by the legislature to the Virginia Normal and Industrial Institute in Petersburg, which in 1946 was renamed to Virginia State University by the legislature). During its existence, the university has operated under four different legal names. The founding name was Virginia Agricultural and Mechanical College. Following a reorganization of the college in the 1890s, the state legislature changed the name to Virginia Agricultural and Mechanical College and Polytechnic Institute, effective March 5, 1896. Faced with such an unwieldy name, people began calling it Virginia Polytechnic Institute, or simply VPI. On June 23, 1944, the legislature followed suit, officially changing the name to Virginia Polytechnic Institute. At the same time, the commonwealth moved most women’s programs from VPI to nearby Radford College, and that school’s official name became Radford College, Women’s Division of Virginia Polytechnic Institute. The commonwealth dissolved the affiliation between the two colleges in 1964. The state legislature sanctioned university status for VPI and bestowed upon it the present legal name, Virginia Polytechnic Institute and State University, effective June 26, 1970. While some older alumni and other friends of the university continue to call it VPI, its most popular–and its official—nickname today is Virginia Tech.

     
  • richardmitnick 1:01 pm on May 20, 2017 Permalink | Reply
    Tags: , , , Yellowstone supervolcano   

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

    Livescience

    [I usually pass up articles on Yellowstone, but this is compelling, even if they are late with it to social media.]

    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.

    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.


    Yellowstone Supervolcano is Roaring Back to Life

    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 [Springer Link]. “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.

    4
    Pictures taken by Peter Hartree between 14.30 and 15.00 on September 4th 2014. I’m sorry for the less than ideal quality of these – this wasn’t a professional photo shoot.
    All photos are unedited. I have a bunch more (fairly similar) shots – if you’d like to see them, write to peter@reykjavikcoworking.is.
    Many thanks to pilot Siggi G for the ride.
    Date 4 September 2014,
    Source http://www.flickr.com/photos/41812768@N07/15146259395/
    Author peterhartree

    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.”

    “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.”

    See the full article here .

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