If the supervolcano underneath Yellowstone erupts again, we may have far less advance warning time than we thought. 
 
 After analyzing minerals in fossilized ash from the most recent mega-eruption, researchers at Arizona State University think the supervolcano last woke up after two influxes of fresh magma flowed into the reservoir below the caldera. 
 
 And in an unsettling twist, the minerals revealed that the critical changes in temperature and composition built up in a matter of decades. Until now, geologists had thought it would take centuries for the supervolcano to make that transition. 
 
 Volcanoes 101 Volcanoes are as dangerous as they are majestic. Over 50 eruptions rock our planet every year. This video helps you understand what causes volcanoes to form and erupt—and shows where they are most likely to be found. 
 
 
 
 A 2013 study, for instance, showed that the magma reservoir that feeds the supervolcano is about two and a half times larger than previous estimates. Scientists also think the reservoir is drained after every monster blast, so they thought it should take a long time to refill. Based on the new study, it seems the magma can rapidly refresh—making the volcano potentially explosive in the geologic blink of an eye. 
 
 “It’s shocking how little time is required to take a volcanic system from being quiet and sitting there to the edge of an eruption,” study co-author Hannah Shamloo told the New York Times. 
 
 Still, Yellowstone is one of the best monitored volcanoes in the world, notes Michael Poland, the current Scientist-in-Charge of the Yellowstone Volcano Observatory for the U.S. Geological Survey. A variety of sensors and satellites are always looking for changes, and right now, the supervolcano does not seem to pose a threat. 
 
 "We see interesting things all the time ... but we haven't seen anything that would lead us to believe that the sort of magmatic event described by the researchers is happening," says Poland via email, adding that the research overall is "somewhat preliminary, but quite tantalizing." 
 
 The new paper adds to a suite of surprises scientists have uncovered over the last few years as they have studied the supervolcano. (Also find out about a supervolcano under Italy that has recently been rumbling.) 
 
 Related: Top 5 Must-See Attractions in Yellowstone 
 
 Today, Yellowstone National Park owes much of its rich geologic beauty to its violent past. Wonders like the Old Faithful geyser and the Grand Prismatic Spring are products of the geothermal activity still seething below the park, which is driven in turn by the vast magma plume that feeds the supervolcano. 
 
 About 630,000 years ago, a powerful eruption shook the region, spewing forth 240 cubic miles’ worth of rock and ash and creating the Yellowstone caldera, a volcanic depression 40 miles wide that now cradles most of the national park. 
 
 That eruption left behind the Lava Creek Tuff, the ash deposit that Shamloo and her ASU colleague Christy Till used for their work, which they presented in August at a volcanology meeting in Oregon. The pair also presented an earlier version of their study at a 2016 meeting of the American Geophysical Union. 
 
 Based on fossil deposits like this one, scientists think the supervolcano has seen at least two other eruptions on this scale in the past two million years or so. Lucky for us, the supervolcano has been largely dormant since before the first people arrived in the Americas. While a handful of smaller belches and quakes have periodically filled the caldera with lava and ash, the last one happened about 70,000 years ago. 
 
 In 2011, scientists revealed that the ground above the magma chamber bulged by up to 10 inches in a span of about seven years. 
 
 "It's an extraordinary uplift, because it covers such a large area and the rates are so high," the University of Utah's Bob Smith, an expert in Yellowstone volcanism, told National Geographic at the time. 
 
 The swelling magma reservoir responsible for the uplift was too deep to create fears of imminent doom, Smith said, and instead the caldera’s gentle “breathing” offered valuable insights into the supervolcano’s behavior. 
 
 In 2012, another team reported that at least one of the past super-eruptions may have really been two events, hinting that such large-scale events may be more common than thought. 
 
 But almost everyone who studies Yellowstone’s slumbering supervolcano says that right now, we have no way of knowing when the next big blast will happen. For its part, the U.S. Geological Survey puts the rough yearly odds of another massive Yellowstone blast at 1 in 730,000—about the same chance as a catastrophic asteroid collision. ||||| Beneath Yellowstone National Park lies a supervolcano, a behemoth far more powerful than your average volcano. It has the ability to expel more than 1,000 cubic kilometers of rock and ash at once — 2,500 times more material than erupted from Mount St. Helens in 1980, which killed 57 people. That could blanket most of the United States in a thick layer of ash and even plunge the Earth into a volcanic winter. 
 
 Yellowstone’s last supereruption occurred 631,000 years ago. And it’s not the planet’s only buried supervolcano. Scientists suspect that a supereruption scars the planet every 100,000 years, causing many to ask when we can next expect such an explosive planet-changing event. 
 
 To answer that question, scientists are seeking lessons from Yellowstone’s past. And the results have been surprising. They show that the forces that drive these rare and violent events can move much more rapidly than volcanologists previously anticipated. 
 
 The early evidence, presented at a recent volcanology conference, shows that Yellowstone’s most recent supereruption was sparked when new magma moved into the system only decades before the eruption. Previous estimates assumed that the geological process that led to the event took millenniums to occur. ||||| Beneath America's fourth most-visited national park, the apocalypse waits. There's a supervolcano under Yellowstone, capable of shooting 1,000 cubic kilometers of rock and ash into the air. Enough to cover the entire planet. And now, scientists are learning that the entire process may happen faster than previously expected. 
 
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 At IAVCEI 2017 in Portland, Oregon, researchers presented evidence that such eruptions only need a few decades of gestation before exploding. Considering how such eruptions are relatively rare, geologically speaking—there are only three known explosions in history, the last one occurring 631,000 years ago—there was an expectation that they needed a lot of preparation beforehand. That assumption is proving to be wrong, showing how much left there is to learn about supervolcanoes. 
 
 "If something like this happened today, it would be catastrophic," says Hannah Shamloo, a geologist at Arizona State, speaking to the American Geophysical Union. "We want to understand what triggers these eruptions, so we can set up warning systems. That's the big-picture goal." 
 
 Alongside her Ph.D. adviser at Arizona State, geologist Christy Till, Shamloo examined two specific sorts of crystals known as phenocrysts, which form as magma cools a beneath a volcano. Varying between 1 and 2 millimeters each, these crystals are too large to have formed during the heat of an eruption. Rather, each crystal starts with a core that grows layer upon layer, forming a rough equivalent to the rings of a tree. 
 
 The outer rims of these phenocrysts show a clear change in temperature and composition occurring over a few decades, a geologic snap of the finger. "We expected that there might be processes happening over thousands of years preceding the eruption," Till tells the New York Times. "It's shocking how little time is required to take a volcanic system from being quiet and sitting there to the edge of an eruption," Shamloo says. 
 
 However, there's still a lot of work to be done before Shamloo's dream of a warning system gets put into place. Scientists still need to figure out how these massive buildups transform into supereruptions. Because if one happens, you'll need to run pretty fast if you want to escape it. 
 
 Source: New York Times ||||| When a supervolcano like Yellowstone erupts, residents may have a few hours to escape once the disaster has started, a new study suggests. 
 
 Can you outrun a supervolcano? New evidence from an ancient eruption suggests the answer is a surprising yes. 
 
 "I wouldn't recommend anyone try to outrun a volcano, but there's a few of us that could," said Greg Valentine, a volcanologist at the University at Buffalo in New York. 
 
 By analyzing rocks trapped in volcanic ash, Valentine and his colleagues discovered the lethal ash flow spread at street speeds — about 10 to 45 mph (16 to 72 km/h). It might be hard to sustain this pace on foot, but it's certainly possible by car. [Big Blasts: History's 10 Most Destructive Volcanoes] 
 
 The findings were published today (March 7) in the journal Nature Communications. 
 
 "It's really interesting how you can have such a violent eruption producing such slow-moving flows," said Valentine, co-author of the new study. "They still devastate a huge area, but they're slow and concentrated and dense," he told Live Science. His collaborators include Olivier Roche, of Blaise Pascal University in France and David Buesch, of the U.S. Geological Survey. 
 
 Of course, the safest way to deal with any rumbling volcano is to get as far away as possible. Lots of distance can prevent the most common cause of death associated with volcanoes: being trapped and suffocated by a torrent of ash, rocks and superhot gas that explode out at speeds of up to 300 mph (about 480 km/h). These "pyroclastic flows" are the real volcanic killer, not lava. A pyroclastic flow wiped out the Roman town of Pompeii, and in 1902, Mount Pelée on Martinique unleashed a pyroclastic flow that killed some 29,000 people. [Preserved Pompeii: Photos Reveal City of Ash] 
 
 You should still evacuate 
 
 Volcanologists try to account for such hazards when planning for future disasters. But it's hard to know what will happen when a supervolcano the size of Yellowstone blows its top. The last supereruption on Earth was 74,000 years ago, in Toba, Indonesia. Looking at the rocky remains of past supereruptions can reveal how and why supervolcanoes erupt. 
 
 These rocks were picked up and moved across the Arizona landscape by pyroclastic flows from the Silver Creek caldera, a supervolcano, eruption 18.8 million years ago. Credit: Greg A. Valentine 
 
 When a supervolcano blew in Arizona 18.8 million years ago, the ash spread more than 100 miles (160 km). This single layer, called the Peach Springs Tuff, is more than 450 feet (140 meters) thick in the area close to the volcano and 10 feet (3 m) thick at its edge, 100 miles away. (A tuff is a volcanic rock made of solidified ash.) 
 
 The researchers measured rocks at the bottom of the tuff in Arizona that were carried in the flow. They matched unique rock types back to their source, and found that many of the rocks, whether fist-size or boulders, were carried no farther than a football field. 
 
 Accounting for the size and position of these rocks helped the researchers build a model of how fast and thick the ash flow was as it traveled. It turns out that only a dense, slow-moving pyroclastic flow could suck up the rocks from the surface and trundle them along. A fast, relatively thin flow would have to reach impossible speeds — up to 1,454 mph (2,340 km/h) — to carry the rocks, the researchers found. 
 
 "I think it's plausible but speculative," said Calvin Miller, a volcanologist at Vanderbilt University in Tennessee, who was not involved in the study. "It will be interesting to see how the [scientific] community responds to it. Even if they're right for the Peach Springs Tuff, this is just part of a continuum of eruption styles," Miller told Live Science. 
 
 The origins of the Peach Springs Tuff can be spotted in southwestern Arizona's Black Mountains, near the town of Oatman. The eruption left behind a very large crater called a caldera, though it has been mostly obliterated by erosion and faulting. 
 
 The caldera, called Silver Creek, spewed magma for several days, releasing a volume of about 1,000 times the Mississippi River's daily flow at New Orleans, Valentine said. "If you think about 1,000 Mississippi Rivers coming out of the ground, you can see how [the ash] would have spread out across a huge area," he said. 
 
 However, one expert on the Peach Springs Tuff doesn't buy the scenario. Charles Ferguson, a research geologist with the Arizona Geological Survey, said there are outcrops that suggest the ash moved quickly and energetically, like a typical pyroclastic flow. 
 
 "I think their hypothesis is more problematic than explanatory," Ferguson told Live Science. 
 
 Southwestern supervolcanoes 
 
 Kodachrome slides, held by geologist Greg Valentine of the University of Buffalo, show images of geologic formations associated with the supereruption of the Silver Creek caldera. Credit: Douglas Levere 
 
 The Peach Springs Tuff covers parts of Arizona, Nevada and California, from Barstow, California, to Peach Springs, Arizona. Geologists use the creamy white and pink rock as a unique marker in the region. 
 
 The western United States suffered at least 100 of these huge eruptions starting about 40 million years ago (a consequence of shifting tectonic plates). It's not clear whether every one of these supervolcanic blasts sent out slowly moving ash flows, but Valentine said he sees similar evidence in other areas. 
 
 The powerful Peach Springs eruption ejected 72 cubic miles (300 cubic km) of pulverized rock into the air. For comparison, the 1980 eruption of Mount St. Helens in Washington blasted out 0.24 cubic miles (1 cubic km) of material. And the 1991 eruption of Mount Pinatubo in the Philippines spewed 2.4 cubic miles (10 cubic km) of material. 
 
 Any supereruption will likely come with a fair amount of warning, similar to the bulge that foreshadowed the Mount St. Helens eruption. The new findings suggest that people living near a supervolcano might have a few hours to evacuate once the disaster starts, the researchers said. 
 
 Follow us @livescience, Facebook & Google+. Original article on Live Science. ||||| An example of the possible distribution of ash from a month-long Yellowstone supereruption. The distribution map was generated by a new model developed by the US Geological Survey using wind information from January 2001. The improved computer model, detailed in a new study published in Geochemistry, Geophysics, Geosystems, finds that the hypothetical, large eruption would create a distinctive kind of ash cloud known as an umbrella, which expands evenly in all directions, sending ash across North America. Ash distribution will vary depending on cloud height, eruption duration, diameter of volcanic particles in the cloud, and wind conditions, according to the new study. Credit: Credit: USGS In the unlikely event of a volcanic supereruption at Yellowstone National Park, the northern Rocky Mountains would be blanketed in meters of ash, and millimeters would be deposited as far away as New York City, Los Angeles and Miami, according to a new study. 
 
 An improved computer model developed by the study's authors finds that the hypothetical, large eruption would create a distinctive kind of ash cloud known as an umbrella, which expands evenly in all directions, sending ash across North America. 
 
 A supereruption is the largest class of volcanic eruption, during which more than 1,000 cubic kilometers (240 cubic miles) of material is ejected. If such a supereruption were to occur, which is extremely unlikely, it could shut down electronic communications and air travel throughout the continent, and alter the climate, the study notes. 
 
 A giant underground reservoir of hot and partly molten rock feeds the volcano at Yellowstone National Park. It has produced three huge eruptions about 2.1 million, 1.3 million and 640,000 years ago. Geological activity at Yellowstone shows no signs that volcanic eruptions, large or small, will occur in the near future. The most recent volcanic activity at Yellowstone—a relatively non-explosive lava flow at the Pitchstone Plateau in the southern section of the park—occurred 70,000 years ago. 
 
 Researchers at the U.S. Geological Survey used a hypothetical Yellowstone supereruption as a case study to run their new model that calculates ash distribution for eruptions of all sizes. The model, Ash3D, incorporates data on historical wind patterns to calculate the thickness of ash fall for a supereruption like the one that occurred at Yellowstone 640,000 years ago. 
 
 The new study provides the first quantitative estimates of the thickness and distribution of ash in cities around the U.S. if the Yellowstone volcanic system were to experience this type of huge, yet unlikely, eruption. 
 
 Cities close to the modeled Yellowstone supereruption could be covered by more than a meter (a few feet) of ash. There would be centimeters (a few inches) of ash in the Midwest, while cities on both coasts would see millimeters (a fraction of an inch) of accumulation, according to the new study that was published online today in Geochemistry, Geophysics, Geosystems, a journal of the American Geophysical Union. 
 
 The figure above shows illustrations of plume shapes that would result from different types of volcanic eruptions. A weak plume (left) typically forms above small eruptions such as the April-May 2010 eruption of the Eyjafjallajökull volcano in Iceland, as shown in this NASA Earth Observatory image. A strong plume with a major umbrella cloud (right) forms during very large eruptions, such as shown in this Japanese Meteorological Agency image of the Pinatubo cloud on June 15, 1991. During superuruptions, umbrella clouds from strong plumes may push their way hundreds or thousands of kilometers upwind, according to a new study published in Geochemistry, Geophysics, Geosystems. Credit: Credit: USGS 
 
 The model results help scientists understand the extremely widespread distribution of ash deposits from previous large eruptions at Yellowstone. Other USGS scientists are using the Ash3D model to forecast possible ash hazards at currently restless volcanoes in Alaska. 
 
 Unlike smaller eruptions, whose ash deposition looks roughly like a fan when viewed from above, the spreading umbrella cloud from a supereruption deposits ash in a pattern more like a bull's eye – heavy in the center and diminishing in all directions – and is less affected by prevailing winds, according to the new model. 
 
 "In essence, the eruption makes its own winds that can overcome the prevailing westerlies, which normally dominate weather patterns in the United States," said Larry Mastin, a geologist at the USGS Cascades Volcano Observatory in Vancouver, Washington, and the lead author of the new paper. Westerly winds blow from the west. 
 
 "This helps explain the distribution from large Yellowstone eruptions of the past, where considerable amounts of ash reached the west coast," he added. 
 
 The three large past eruptions at Yellowstone sent ash over many tens of thousands of square kilometers (thousands of square miles). Ash deposits from these eruptions have been found throughout the central and western United States and Canada. 
 
 Erosion has made it difficult for scientists to accurately estimate ash distribution from these deposits. Previous computer models also lacked the ability to accurately determine how the ash would be transported. 
 
 Using their new model, the study's authors found that during very large volcanic eruptions, the expansion rate of the ash cloud's leading edge can exceed the average ambient wind speed for hours or days depending on the length of the eruption. This outward expansion is capable of driving ash more than 1,500 kilometers (932 miles) upwind – westward—and crosswind – north to south—producing a bull's eye-like pattern centered on the eruption site. 
 
 In the simulated modern-day eruption scenario, cities within 500 kilometers (311 miles) of Yellowstone like Billings, Montana, and Casper, Wyoming, would be covered by centimeters (inches) to more than a meter (more than three feet) of ash. Upper Midwestern cities, like Minneapolis, Minnesota, and Des Moines, Iowa, would receive centimeters (inches), and those on the East and Gulf coasts, like New York and Washington, D.C. would receive millimeters or less (fractions of an inch). California cities would receive millimeters to centimeters (less than an inch to less than two inches) of ash while Pacific Northwest cities like Portland, Oregon, and Seattle, Washington, would receive up to a few centimeters (more than an inch). 
 
 Even small accumulations only millimeters or centimeters (less than an inch to an inch) thick could cause major effects around the country, including reduced traction on roads, shorted-out electrical transformers and respiratory problems, according to previous research cited in the new study. Prior research has also found that multiple inches of ash can damage buildings, block sewer and water lines, and disrupt livestock and crop production, the study notes. 
 
 The study also found that other eruptions – powerful but much smaller than a Yellowstone supereruption—might also generate an umbrella cloud. 
 
 "These model developments have greatly enhanced our ability to anticipate possible effects from both large and small eruptions, wherever they occur," said Jacob Lowenstern, USGS Scientist-in-Charge of the Yellowstone Volcano Observatory in Menlo Park, California, and a co-author on the new paper. 
 
 Explore further: Volcanic eruption begins under Iceland glacier 
 
 More information: onlinelibrary.wiley.com/doi/10 … 014GC005469/abstract
– Should it ever erupt, a supervolcano beneath Yellowstone National Park could blanket North America in an ash cloud, wipe out communications, and alter the climate. Given that eruptions of supervolcanoes buried on our planet—and there are several—are thought to occur every 100,000 years or so, however, the likelihood of such an event during your lifetime is small, reports the New York Times. As comforting as that may be, new research out of Arizona State University is far less so. Whereas researchers previously thought such an eruption would be centuries or millennia in the making, an analysis of fossilized ash left over from Yellowstone's last supereruption 630,000 years ago reveals the process could take only decades. Tiny crystals left over from underground magma at Yellowstone show the first sign of the last supereruption was a spike in temperature that coincided with the movement of new magma into the reservoir beneath the supervolcano. The crystals also reveal a supereruption followed much quicker than scientists previously thought—perhaps within decades, or what Popular Mechanics calls "a geologic snap of the finger." This is the first indication that "the conditions that lead to supereruptions might emerge within a human lifetime," which one researcher describes as "shocking," per the Times. For now, though, you can rest easy. The lead scientist at the Yellowstone Volcano Observatory tells National Geographic there's no sign of any "magmatic event" at this time. (You might outrun a supervolcano's lava anyway.)