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  • richardmitnick 10:07 am on April 21, 2017 Permalink | Reply
    Tags: An Improved Model of How Magma Moves Through the Crust, , Volcanic eruptions of basalt are fed by intrusions of magma called dikes which advance through Earth’s crust for a few hours or days before reaching the surface, Volcanoes   

    From Eos: “An Improved Model of How Magma Moves Through the Crust” 

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    Eos

    18 April 2017
    Terri Cook

    Researchers have developed a new numerical model that can, for the first time, solve for both the speed and the path of a propagating dike.

    1
    A new model that simulates the speed and path of magma spreading through Earth’s crust may help scientists predict when and where eruptions may occur on Italy’s Mount Etna (pictured) and other active volcanoes. Credit: gnuckx

    Volcanic eruptions of basalt are fed by intrusions of magma, called dikes, which advance through Earth’s crust for a few hours or days before reaching the surface. Although many never make it that far, those that do can pose a serious threat to people and infrastructure, so forecasting when and where a dike will erupt is important to assessing volcanic hazards.

    However, the migration of magma below a volcano is complex, and its simulation is numerically demanding, meaning that efforts to model dike propagation have so far been limited to models that can quantify either a dike’s velocity or its trajectory but not both simultaneously. To overcome this limitation, Pinel et al. have developed a hybrid numerical model that quantifies both by dividing the simulations into two separate steps, one that calculates a two-dimensional trajectory and a second that runs a one-dimensional propagation model along that path.

    The results indicate that the migration of magma is heavily influenced by surface loading—the addition or removal of weight on Earth’s surface—such as that caused by the construction of a volcano or its partial removal via a massive landslide or caldera eruption. The team confirmed previous research that showed that increasing surface load attracts magma while also reducing its velocity, whereas unloading diverts much of the magma.

    To test their approach, the team applied their model to a lateral eruption that occurred on Italy’s Mount Etna in July 2001. The eruption was fed by two dikes, including one that in its final stages clearly slowed down and bent toward the west while still 1–2 kilometers below the surface. The results showed that the two-step model was capable of simulating that dike’s velocity and trajectory and thus offers a new means of constraining the local stress field, which partially controls these properties.

    In the future, report the authors, more complex versions of this model that incorporate information on local topography and magmatic properties could be integrated with real-time geophysical data to improve forecasts of when and where a propagating dike could erupt at the surface. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1002/2016JB013630, 2017)

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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 5:28 pm on March 3, 2017 Permalink | Reply
    Tags: , , , Volcanoes   

    From The Atlantic: “The Scary State of Volcano Monitoring in the United States” 

    Atlantic Magazine

    The Atlantic Magazine

    Feb 28, 2017
    Adrienne LaFrance

    One of the most volcanically active countries in the world is not ready for a devastating eruption.


    The lava flow from the Kilauea volcano moves over a fence on private property near the village of Pahoa, Hawaii, in 2014.

    One of the most volcanically active countries in the world is not ready for a devastating eruption.

    Thirteen days before Christmas, somewhere in the frigid waters of the Bering Sea, a massive volcano unexpectedly rumbled back to life.

    Just like that, Bogoslof volcano began its first continuous eruption since 1992, belching great plumes of ash tens of thousands of feet into the cold sky over the Aleutian islands, generating volcanic lightning, and disrupting air travel—though not much else.

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    Bogoslof volcano. Posted: Dec 24 2016, 7:11am CST | by Sumayah Aamir, in News | Latest Science News

    The volcano is on a tiny island about 60 miles west of Unalaska, which is the largest city in the Aleutians. It has a population of about 5,000 people.

    Bogoslof hasn’t quieted yet. One explosion, in early January, sent ash 33,000 feet into the air. Weeks later, another eruption lasted for hours, eventually sprinkling enough ash on the nearby city to collect on car windshields and dust the snow-white ground with a sulfurous layer of gray. Over the course of two months, Bogoslof’s intermittent eruptions have caused the island to triple in size so far, as fragments of rock and ash continue to pile atop one another.

    Geologists don’t know how long the eruption will last. In 1992, the activity at Bogoslof began and ended within weeks. But more than a century ago, it erupted continuously for years. In the 1880s, volcano observers in the Aleutians had little but their own senses to track what was happening. Today, scientists use satellite data and thermal imagery to watch Bogoslof—signs of elevated temperatures in satellite data indicate that lava has bubbled to the surface, for example. But monitoring efforts are nowhere near what they could be. For the relatively remote Bogoslof, the absence of ground-level sensors is inconvenient, perhaps, but not necessarily alarming. Elsewhere, the dearth of volcano sensors poses a deadly problem.

    There are at least 169 active volcanoes in the United States, 55 of which are believed to pose a high or very high threat to people, according to a 2005 U.S. Geological Survey report.

    About one-third of the active volcanoes in the U.S. have erupted—some of them repeatedly—within the past two centuries. Volcanoes aren’t just dangerous because of their fiery lava. In 1986, volcanic gas killed more than 1,700 people in Cameroon. And one of the latest theories about the epic eruption at Pompeii, in 79 A.D., is that many people died from head injuries they sustained when boulders rained down on them.

    Hawaii’s Kilauea, Washington’s Mt. St. Helens, and Wyoming’s Yellowstone all have extensive monitoring. But many volcanoes in the Cascades have only a couple of far-field sensors, several geologists told me. The Pacific Northwest, which includes high-population areas in close proximity to active volcanoes, is of particular concern for public safety.

    “Most people in the U.S. perceive volcanic eruptions as rare, and [believe] that we’d be able to get advance notice because of the advance in science and instrumentation,” said Estelle Chaussard, an assistant professor of geophysics and volcanology at the State University of New York at Buffalo. “However, the massive eruption of Mount St. Helens, in Washington, was only 37 years ago, and it took until the volcano became active again in 2004 to start a truly comprehensive monitoring. … This kind of assumption is therefore very dangerous, because most of our volcanoes are not as intensively monitored as we think they are or as they should be.”

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    Mount St. Helens Is Recharging Its Magma Stores, Setting Off Earthquake Swarms. https://www.wired.com


    Mount St. Helens spews steam and gray ash from a small explosive eruption in its crater on October 1, 2004. (John Pallister / USGS / Reuters)

    Almost half of the active volcanoes in the country don’t have adequate seismometers—tools used to track the earthquakes that often occur during volcanic eruptions. And even at the sites that do have seismometers, many instruments—selected because they are cheaper and consume less power—are unable to take a complete record of the ground shaking around an eruption, meaning “the full amplitude of a seismogram may be ‘clipped’ during recording, rendering the data less useful for in-depth analyses,” according to a 2009 report by the U.S. Geological Survey.

    “Using satellite radar and other systems, it should be possible to systematically keep a close eye on most all hazardous volcanoes around the world,” said Roland Bürgmann, a professor of planetary science at the University of California at Berkeley. “Currently, some volcanoes in the U.S. and globally are well-monitored, but most are not.”

    GPS helps fill in some of the gaps. As magma accumulates at the Earth’s surface, the ground bulges upward—and that bulge can be measured from space, using radar bounced off the ground. “That’s a big advance, because you don’t need sensors on the ground and, in theory, you could monitor all the Earth’s volcanoes,” said Paul Segall, a professor of geophysics at Stanford University. “The trouble is, there’s nothing up there that is designed to do that, and the orbital repeat times aren’t frequent enough to do a really good job.”

    “In my view,” he added, “We haven’t even gotten up to bare bones, let alone more sophisticated monitoring.”

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    A plume from the Bogoslof eruption can be seen from Unalaska Island, 53 miles away from the volcano, on February 19, 2017. (Janet Schaefer / AVO)

    That’s part of why a trio of U.S. senators is reintroducing legislation aimed at improving the country’s volcano monitoring efforts. “For the past 34 years, we have experienced first-hand the threat of volcanic activity to our daily lives with the ongoing eruption at Kilauea,” Senator Mazie Hirono, a Democrat from Hawaii, said in a statement about the bill. “As recently as 2014, we had evacuations and damage to critical infrastructure and residences.”

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    Looking up the slope of Kilauea, a shield volcano on the island of Hawaii. In the foreground, the Puu Oo vent has erupted fluid lava to the left. The Halemaumau crater is at the peak of Kilauea, visible here as a rising vapor column in the background. The peak behind the vapor column is Mauna Loa, a volcano that is separate from Kilauea.

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    Mauna Loa lava flows tend to be larger and move faster than at nearby Kilauea. HVO image from 1984, person for scale. https://www.soest.hawaii.edu/GG/HCV/maunaloa.html

    The Hawaiian Volcano Observatory, on Hawaii’s Big Island, has been monitoring volcanoes since 1912—nearly four decades before Hawaii became a state. Today it’s considered one of the world’s leading observatories. Yet there’s little coordination between even the best observatories in the United States. The Senate bill calls for the creation of a Volcano Watch Office that will provide continuous “situational awareness of all active volcanoes in the U.S. and its territories,” and act as a clearinghouse for the reams of volcanic data that new sensor systems would collect.“Long-records of activity are especially important in volcano monitoring to successfully identify behaviors that differ from the ordinary,” Chaussard told me in an email, “and not all of our volcanoes have such records.”

    “Essentially everything we do now is empirical,” Segall told me, “but most of the really dangerous volcanoes haven’t erupted in modern instrumental times.”

    More data means a better opportunity to identify eruption warning signs, which Segall hopes could eventually make it possible to forecast volcanic activity the way we can predict severe weather like hurricanes. “I don’t know if it’s possible, but it seems a worthy goal,” he said. “We obviously have less ability to peer into the Earth as we do to peer into the sky.”

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  • richardmitnick 11:29 pm on March 1, 2017 Permalink | Reply
    Tags: , , Volcanoes,   

    From Wired: “Italy’s Etna Volcano Throws Lava Bombs in Its First Big Eruption of 2017” 

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    WIRED

    03.01.17
    Eric Clemetti

    1
    Europe’s biggest and most powerful volcano, Mount Etna, erupts sending an ash cloud across the holiday isle of Sicily.

    After one of the most quiet years in decades, Etna has decided to make 2017 a little more exciting. Early this week, the volcano had a moderate strombolian eruption, what the folks who monitor Etna call a “paroxysm,” that produced a lava fountain over the summit of the volcano. Strombolian eruptions (named after nearby Stromboli) are caused by gas-rich magma reaching the surface and erupting explosively. They also tend to produce lava flows at the same time, but they are less intense explosions than a plinian eruption (like what happened at Pinatubo or St. Helens).

    Some of the images of the eruption show a stream of lava coming from the New Southeast Crater while strombolian explosions threw lava bombs hundreds of meters from the vent. The ash from this eruption did not disrupt the air traffic in or out of the airport at nearby Catania—however, past stronger eruptions have caused it to shut down.

    Of course, there was a torrent of hyperbole published about this eruption. But even as dramatic as this eruption looked, it is relatively benign, mainly impacting the summit area of Etna. Always be skeptical of news articles that sell any volcanic eruption as a portend of doom or massive destruction.

    Very few actually are as hazardous as breathless media outlets would suggest. Eruptions at Etna may pose a hazard to air traffic through ash emissions, and slow-moving lava flows could endanger some of the villages and homes on the lower slopes of the volcano. This has happened before, and attempts were made to divert the lava flows (with moderate success). But the lava flow jeopardizes property much more than life; the flows move so slowly that you can likely out-walk them. Etna does have some history of explosive eruptions, but in its most recent activity over the last decade, these events have been very rare.

    Remember, there are a lot of webcams pointed at Etna. You can see a lot of different views (including IR thermal camera) on the INGV webcams, while Radio7 has a variety from different views and EtnaGuide has some near the summit. The next time Etna rumbles, be sure to check it out live.

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  • richardmitnick 12:42 pm on February 22, 2017 Permalink | Reply
    Tags: India's Barren Island volcano erupts, , Volcanoes   

    From Science Times: “India’s Only Active Volcano Wakes Up From Deep Slumber” 

    Science Times

    Science Times

    Feb 22, 2017
    Jaswin S. Singh

    1
    (Photo : Fox News / YouTube) Barren Island volcano erupts off India’s eastern coast. Scientists witnessed eruption from one nautical mile away, were unable to land due to dangerous volcanic activity.

    India’s only volcano is said to be active again. The only volcano of the very vast country, in the Barren Island is active again as scientists saw it spewed out lava and smoke.

    The Barren volcano had been dormant for the last 150 years, CNN reported. It had been active when it first erupted in 1991, then in 1995 then the last was in 2005. It is located at Barren Island volcano, on a isolated unoccupied island off the country’s eastern coast.

    Indian scientists have been observing the Barren volcano for eight hours on January 23 and 25. They saw ash clouds in daytime and fountains of red lava coming out of the volcano’s mouth and flowing down its slopes at night. India’s National Institute of Oceanography or NIO have been collecting samples of the lava and ashes of the Barren volcano. They noted that the volcano is erupting in small scale for five to 10 minutes long.

    “We are checking the composition of the lava and powdering the black sand to figure out the components,” Abhay Mudholkar, who is heading the NIO team which is collecting samples in the Andaman basin, said on Friday. According to Times Of India, the Andaman basin is known for its strong seismicity, submarine volcanoes and hydrothermal activity. Researchers from Council of Scientific & Industrial Research (CSIR) have also visited the site and have collected samples from the basin.

    Scientists from CSIR-NIO recognized many small underwater volcanoes in a linear chain called a volcanic arc. When B Nagender Nath revisited the site, his team from CSIR saw the spewing of smoke and lave of Barren volcano. The collected sample will help identify the volcaninc activity of the volcano. The scientists are hoping to find out as to why Barren Island volcano becomes active after 10 years of being quiet.

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  • richardmitnick 5:15 pm on February 10, 2017 Permalink | Reply
    Tags: , , Deccan Traps eruption, Volcanoes   

    From COSMOS: “Two huge magma plumes fed the Deccan Traps eruption” 

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    COSMOS

    10 February 2017
    Kate Ravilious

    1
    Thick lava flows in Hawaii are nothing compared to the mammoth rivers of hot rock that rolled across in India in the late Cretaceous. New research suggests those flows were fed by two magma sources. Justinreznick / Getty Images

    Some 65 million years ago, the skies over India darkened as one of Earth’s biggest volcanic eruptions burbled from below. It rumbled on for millions of years, blocking out sunlight and casting a chill globally, to produce what we know today as the Deccan Traps.

    Many believe the eruption sent the dinosaurs into severe demise before an asteroid collision finally finished them off. But just how the Earth produced such vast volumes of lava (covering an area greater than the Australian states of New South Wales and Victoria combined) has remained a bit of a mystery. Now a new study by a pair of geologists in Canada shows that the eruption may have been fed by not one, but two deep mantle plumes.

    Like the hot air that rises to create a thundercloud, mantle plumes are thought to be narrow regions of convection that fast-track hot material all the way up from the core-mantle boundary and through the Earth’s 2,900-kilometre-thick layer of hot rock called the mantle.

    There are thought to be a number of active mantle plumes today, some of which have created a chain of volcanic islands as the oceanic plate glides across the plume top. The Hawaiian-Emperor seamount chain, the Easter Islands and the Walvis Ridge (culminating in the island of Tristan da Cunha) are just a few examples.

    By calculating past movements of tectonic plates, scientists have shown that the mantle plume currently underneath the Indian Ocean Island of Réunion was probably responsible for melting the mantle underneath the Deccan region 66 million years ago. But scientists have remained perplexed as to how one mantle plume could produce such a prodigious volume of melt.

    Petar Glišović and Alessandro Forte from the University of Quebec in Montréal, Canada, decided to revisit the Deccan conundrum using a model of mantle convection and running it in reverse for 70 million years.

    “This is a really hard problem as it is impossible to undo heat diffusion,” explains James Wookey, a geophysicist at the University of Bristol in the UK, who wasn’t involved with the study.

    So the pair ran many iterations of their model, with each scenario starting 2.5 million years ago with a different mantle structure configuration, and run forwards until one produced current mantle conditions.

    Taking the best fit and rewinding mantle dynamics by 70 million years, Glišović and Forte’s model showed that the Réunion mantle plume was situated underneath the Deccan region of India, as expected, but to their surprise there was also another mantle plume nearby at that time, responsible for feeding the volcanism on the East African island of Comoros today.

    Publishing in Science, Glišović and Forte calculated that the combined heat of the Réunion and Comoros mantle plumes would have been sufficient to melt around 60 million cubic kilometres of mantle at the time of the eruption; more than enough to feed the Deccan Traps. “We see mantle plumes merging and splitting in our forward running models of mantle convection, so the idea that these two plumes merged in the past is certainly plausible,” says Wookey.

    The model also shows that the Comoros plume had lost most of its heat by 40 million years ago, while the Réunion mantle plume ran out of steam around 20 million years ago. Today, both plumes are mere shadows of their former selves. But Wookey cautions against taking the findings too literally, adding: “the physics of the model is reasonable, but whether the mantle movements are precisely what the Earth actually did is another matter.”

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  • richardmitnick 1:13 pm on February 7, 2017 Permalink | Reply
    Tags: , Network for Observation of Volcanic and Atmospheric Change (NOVAC), The tricky science of tracking and predicting volcanic eruptions, Volcanoes   

    From COSMOS: “The tricky science of tracking and predicting volcanic eruptions” 

    Cosmos Magazine bloc

    COSMOS

    07 February 2017
    Kate Ravilious

    1
    The Japanese city of Kagoshima sits near the base of the active volcano Sakurajima. Jim Holmes / Getty Images

    It was just after 3pm on 13 November 1985 when the Colombian volcano Nevado del Ruiz erupted. Within minutes, four deadly rivers of clay, ice and molten rock raced down its flanks, destroying towns and villages.

    More than 23,000 people died, making it the second deadliest volcanic disaster in the 20th century – outranked only by the 1902 eruption of Mount Pelée in the Caribbean, which killed 30,000.

    There had been mini-eruptions and earthquakes in the run-up to the Colombian event, but while scientists noted such rumblings, they had no way of knowing whether they were just minor tantrums or harbingers of something worse.

    Since then, the science of eruption forecasting has come a long way. In 1991, 75,000 people were evacuated prior to the massive explosion of the Mount Pinatubo on the Philippine island of Luzon. In 2010, 70,000 were moved out of harm’s way before Indonesia’s Mount Merapi erupted.

    That’s not to say forecasting has become infallible. In 2014, Mount Ontake in Japan erupted unexpectedly, killing 57 people. And in many areas people live in the shadows of dangerous volcanoes that are not monitored at all.

    But new methods of remote forecasting, combined with powerful computer models, promise to be a game changer.

    Around the world are an estimated 1,550 active volcanoes. Most signal their vitality with just an occasional rumble, around 20 are non-stop fumers that don’t erupt – and about 50 explode each year. A handful of these are big enough to cause problems.

    To forecast big blasts, scientists measure fumes emanating from within the rocks. Changes in the ratio of carbon dioxide to sulfur dioxide can be a clue to restlessness down below. When magma starts to move upwards, carbon dioxide, being less soluble, bubbles out first. It’s followed by a belch of sulfur dioxide as the magma nears the surface.

    For decades, the only way to measure these gases involved walking up the slopes towards the crater, or swooping past in an aircraft – both risky activities, especially once an eruption is underway – and especially if scientists wanted to see how gas composition changed while the volcano was actually erupting.

    Since 2005, though, an international group of researchers has been developing instruments to monitor the target gases remotely and continuously. Known as the Network for Observation of Volcanic and Atmospheric Change (NOVAC) [no link to any organization found, but many articles], group members use portable low-cost spectrometers that analyse gas concentrations based on how sunlight is absorbed as it passes through the volcanic plume.

    Another meter measures changing levels of sulfur dioxide and can be installed kilometres downwind of active vents or on aircraft and satellites, allowing continuous monitoring.

    At present, some 35 volcanoes around the world are watched this way.

    A type of spectrometer known as a multi-GAS analyser continuously measures the ratio of carbon dioxide to sulfur dioxide. It is installed right on the edge of volcanic craters, inside the plume.

    In Costa Rica, these instruments are now successfully sniffing out tell-tale bad volcano breath, providing a valuable early warning service. Early in 2014, Maarten de Moor, from the country’s Volcanic and Seismic Observatory, installed gas sensors on Turrialba, a volcano that threatens the capital city of San José, which lies just 30 kilometres to its west.

    Around six months later, an eruption kicked off. Prior to each ejection, de Moor and his colleagues saw a sharp increase in the carbon-sulfur ratio. “It is a really promising result and a huge step forward for eruption forecasting,” de Moor says.

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    On 20 May 2016, the Turrialba volcano started erupting columns of smoke and ash that the wind extended towards the Costa Rican capital of San Jose. EZEQUIEL BECERRA / AFP / Getty Images

    So far, the activity of Turrialba has been small, but de Moor is worried. “The last large eruption on Turrialba was in 1864,” he says. “The ash deposits suggest that it started with small eruptions, like those we are seeing now.”

    The little disturbances, he continued, gave way to an enormous outburst – dubbed “Strombolian” in the jargon of the discipline, a reference to an ultra-active volcano on the island of Stromboli, off the coast of Sicily in the Tyrrhenian Sea. Such a powerful eruption from Turrialba would devastate the surrounding terrain, potentially killing thousands and crippling Costa Rica’s economy.

    The change to the carbon/sulfur ratio picked up by NOVAC’s spectrometers, though, turns out not to be a reliable early warning signal in every case. It was not recorded, for instance, on Turrialba’s neighbour, Poas, before its most recent eruption.

    The explanation for its absence concerns the acidic lake that fills Poas’s crater. The lake absorbs sulfur dioxide while allowing carbon dioxide to pass through, resulting in a markedly different gas profile. As pressure built and an eruption became imminent, the lake became super-saturated with sulfur dioxide, meaning the excess gas passed through into the atmosphere. This produced a different, but equally telling, change in the ratio, a clear warning that trouble was afoot.

    Deciphering this signal from Poás was a milestone, de Moor says, since many of the world’s most unpredictable and explosive volcanoes – including Nevado del Ruiz and Mount Ontake in Japan – have crater lakes.

    The two Costa Rican volcanoes underscore that “there is no one size fits all” eruption signal, he adds.

    The signal that warned of Turrialba’s eruptions was not repeated at its neighbouring volcano, Poás – it produced the opposite signal to Turrialba prior to eruption. The acidic crater lake on Poás normally absorbs sulfur dioxide but allows carbon dioxide to bubble through, creating a permanently high carbon/sulfur ratio in the gas cloud plume.

    But in the days prior to an eruption, the carbon/sulfur ratio fell; the lake could not keep pace with the excess sulfur dioxide accompanying the rising magma. Deciphering this signal from Poás is a milestone, de Moor says, since many of the world’s most unpredictable and explosive volcanoes – including Nevado del Ruiz in Columbia and Mount Ontake – have crater lakes.

    And the Costa Rican volcanoes underscore that “there is no one size fits all” eruption signal, he adds.

    The key to successful prediction is to combine gas and classic seismic monitoring, as well as deploying new techniques that reveal whether the volcano is actually swelling with magma.

    A satellite’s GPS can monitor the movement of a volcano’s surface. Volcanologist James Hickey at the University of Exeter in the UK used this type of data to generate a computer model of what was happening underneath Sakurajima, an active volcano in Kyushu, Japan.

    Sakurajima’s last major eruption took place in 1914, killing 58 people and causing a massive flood in the nearby seaside city of Kagoshima. Its magma chambers have been refilling since, causing minor eruptions virtually every day.

    Hickey and his colleagues incorporated the area’s topography and underlying rock types into their model, along with very precise GPS measurements of surface movement, to gauge just how fast the magma was replenishing. Their results, published in Scientific Reports last September, indicate the tank needs roughly 130 years to fill.

    “In other words […] enough magma might be stored in the next 30 years for an eruption of the same scale as one in 1914,” Hickey says.

    That finding prompted the Kagoshima City Office to review its evacuation plans. Meanwhile, Hickey is developing similar models for volcanoes in Ecuador and the Lesser Antilles in the Caribbean.

    But even with all the high-tech advances, people in the poorest parts of the world are still at risk. Despite the efforts of NOVAC, right now there are still too few experts to analyse every volcano’s halitosis and generate the models that reveal what is going on deep underground. “We hope to interest more people in coming to do this kind of work,” de Moor says.

    In many countries with significant populations living in volcanic danger zones, there is barely any monitoring at all. Indonesia and the Philippines top the list for populations most at threat, according to a 2015 United Nations report.

    But at least in Colombia, 30 years after the devastation, villagers living under the menacing shadow of Nevado de Ruiz are placing their hopes in science.

    Continuous gas monitoring instruments were installed in the volcano’s vent last year and scientists are schooling themselves in how to read warning signs.

    With luck, they’ll have sussed it out before she blows again.

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  • richardmitnick 12:47 pm on February 7, 2017 Permalink | Reply
    Tags: , Kamokuna lava delta, Lava tube, , Volcanoes   

    From Science Alert: “WATCH: Sea cliffs just collapsed in on this Hawaii’s ridiculous ‘lava tube’ “ 

    ScienceAlert

    Science Alert

    6 FEB 2017
    BEC CREW

    11
    USGS

    Nature is out of control.

    If watching a thick, red stream of molten lava pour into the Pacific Ocean like the world’s biggest bloody Mary isn’t enough to make you gape at how utterly bananas nature can be, how about the moment when the whole thing collapses in on itself?

    Last month, the US Geological Survey (USGS) released incredible footage of that lava ‘firehose’ pouring from a crack in Hawaii’s Kilauea volcano, the sea cliffs that supported it collapsed, and it’s a stark reminder that nature DNGAF.

    The lava tube itself formed on New Year’s Eve, when a massive section of the Kamokuna lava delta, in Hawaii’s Volcanoes National Park on the southeast side of the Big Island, collapsed into the ocean, exposing the volcano’s molten insides.

    Since then, the lava tube has been flowing into the Pacific Ocean some 21 metres (70 feet) below the exposure point, as one continuous stream of molten rock stretching up to 2 metres across at its widest point.

    2
    USGS

    While it looked spectacular, tourists were advised to keep well away from the exposed lava delta, because as the lava hits the cool ocean waters, it causes a reaction that sends exploding chunks of hot rock and debris back in towards the land.

    “When the lava delta collapsed, solid and molten fragments of lava and superheated steam exploded skyward, creating tremendous hazard for anyone who ignored the warning signs and entered the closed area on land or ventured too close to the lava delta by boat,” the USGS reported on January 1.

    “[It’s] definitely the most dramatic firehose event I’ve ever witnessed in the last three decades of viewing lava,” Shane Turpin from Lava Ocean Tours in Hawaii told Phys.org.

    Here’s footage of the delta collapsing and exposing the lava tube:

    And here’s the lava tube in all its thunderous glory, filmed on January 25:

    If all that molten lava streaming through the rock face for over a month non-stop seems kinda unsustainable, it was, because the USGS just announced that the cliffs have collapsed in on themselves, destroying the lava tube in the process.

    “Within minutes of HVO (Hawaiian Volcano Observatory) geologists reaching the ocean entry site, the sea cliff seaward of the hot crack collapsed with no warning. Fortunately, they were far enough away to not be in harm’s way,” the USGS reported on February 2.

    “When they arrived, the ‘firehose’ flow was no longer visible. However, spatter (bits of molten lava) and black sand flying through the steam plume indicated that lava was still flowing into the ocean and interacting explosively with seawater.”

    As for the Kilauea volcano, it’s been erupting continuously since 1983, so while the ‘great firehose’ might have disappeared for the time being, this certainly isn’t the last time we can expect activity from the ancient formation.

    “There’s no indication of it slowing down or stopping,” USGS geologist, Janet Babb, told Phys.org.

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  • richardmitnick 9:20 am on January 5, 2017 Permalink | Reply
    Tags: Hawaii's famous Kamokuna lava delta, Kīlauea volcano, , Volcanoes   

    From Science Alert: “WATCH: A chunk of Hawaii just collapsed into the ocean” 

    ScienceAlert

    Science Alert

    4 JAN 2017
    FIONA MACDONALD

    1
    NPS Photo/Travis Delimont

    Oops.

    On New Year’s Eve, a 22-acre (9-hectare) chunk of Hawaii’s famous Kamokuna lava delta collapsed into the ocean, triggering huge waves and showers of volcanic rock, and almost taking five tourists with it.

    The Kamokuna lava delta is formed where lava spewing out of the Big Island’s Kīlauea volcano meets the Pacific Ocean and rapidly cools, forming new land.

    2
    You might want to get out of the way. Page Films. Science Alert Watch: Hawaii’s terrifying lava flow consumes everything in its path.

    3
    English: Looking up the slope of Kilauea, a shield volcano on the island of Hawaii. In the foreground, the Puu Oo vent has erupted fluid lava to the left. The Halemaumau crater is at the peak of Kilauea, visible here as a rising vapor column in the background. The peak behind the vapor column is Mauna Loa, a volcano that is separate from Kilauea.
    Date 17 October 2011, 00:57 (UTC)
    Source Puu_Oo_looking_up_Kilauea.jpg

    It’s a popular tourist spot, but, as you can see in the crazy footage below, the striking black cliff that the lava flow forms isn’t very stable. This footage shows only part of the delta collapse, which continued into the night as the waves washed away more of the cliff face:


    Access mp4 video here .

    The entire Kamokuna ocean entry lava delta was only 26 acres (10.5 hectares), which means a whole chunk of it is now lost to the ocean, including the tourist viewing platform.

    The area – including the air space 1,000 feet (304 metres) above the delta – has now been temporarily closed, while the US National Park Service secures the region.

    “Fortunately, there were no aircraft or boats reported in the area at the time of the collapse, nor were any visitors on the delta itself, which is closed for public safety,” said Park Superintendent Cindy Orlando.

    “Had anyone been close by on land, water or air, lives would have surely been lost.”

    Lava deltas are known for being pretty dangerous places to hang out. The Kīlauea volcano has been erupting steadily since 1983, but the new land formed by the cooling lava is built on unstable sand and substrate, which makes it incredibly susceptible to collapse.

    Not only that, but as the lava enters the ocean, it produces a highly corrosive plume of hydrochloric acid and volcanic particles, which means it’s always a pretty risky place for tourists to visit.

    But it’s uncommon for so much of the delta to fall away over a few hours.

    The collapse began around 2 pm Hawaiian time on New Year’s Eve, causing officials to shut off the viewing platform and monitor the situation. But at 7pm, five tourists ducked beneath the closure line to check out the cliff, ignoring warnings.

    Around 15 minutes after a ranger retrieved them, the section of cliff they were standing on crashed into the ocean.

    “It was a really close brush with death for them,” said eruption crew ranger Travis Delimont. “Luckily, they finally listened to us and turned around in time.”

    As dangerous as the area is at this time, all that churning ocean and lava has actually created an incredibly beautiful phenomenon. The owner of Epic Lava Tours, John Tarson, captured this footage of the delta on January 2:


    Access mp4 video here .

    It’s pretty incredible. But let’s enjoy that raging natural beauty from behind the safety of our computers until the area’s stable again, shall we?

    See the full article here .

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  • richardmitnick 12:38 pm on January 3, 2017 Permalink | Reply
    Tags: Bogoslof Island, , Volcanoes   

    From NYT: “An Alaskan Volcano Erupts, Largely Out of View” 

    New York Times

    The New York Times

    DEC. 30, 2016
    HENRY FOUNTAIN

    1
    An image of an eruption plume from Bogoslof was captured on Dec. 20 from an airplane window. Credit Paul Tuvman/Alaska Volcano Observatory.

    For a mere flyspeck, Bogoslof Island has been causing quite a commotion recently.

    The island is the exposed summit of a volcano that sits in 6,000 feet of water in the Bering Sea about 40 miles west of the Alaskan island of Unalaska, which is part of the Aleutian chain. Bogoslof has had a series of eruptions over the last several weeks, spewing gases and ash into the skies and prompting aviation warnings.

    An eruption on Friday, which produced an ash cloud that was believed to rise to about 20,000 feet, was the sixth since Dec. 20. But Michelle Coombs, a geologist with the United States Geological Survey and scientist-in-charge of the Alaska Volcano Observatory, said that analysis of seismic data revealed several more eruptions earlier in the month.

    Alaska, where the Pacific Ocean plate is slowly sliding, or subducting, beneath the North American plate, is home to many volcanoes, 52 of which have been active in the last three centuries. But only about 30 of them have seismometers and other instruments to readily detect eruptions.

    Bogoslof, which last erupted in 1992, is remote and all of its exposed land — about a quarter of a square mile — is protected as part of the Alaska Maritime National Wildlife Refuge. As a result, there are no instruments there.

    Instead, the volcano observatory relies on equipment installed at other locations, as well as satellites, to determine if an eruption has occurred. “It’s a fun bit of detective work trying to put all the pieces together,” Dr. Coombs said.

    Among the information they use is data from the World Wide Lightning Location Network, which has sensors in 40 locations to detect and pinpoint lightning flashes. Dr. Coombs said ash clouds, like thunder clouds, produce lightning, and since thunderstorms are rare in that part of Alaska, “if we see lightning that is geographically near a volcano, the odds are pretty good that that could be from an eruption.”

    Satellite images show that the volcano is erupting from a vent that is just offshore, under the water, and as new material piles up it is changing the shape of the island. “You can see in these images that a new volcanic cone is being built,” Dr. Coombs said. “If it continues, it might build a cone that is above seawater.”

    There is some risk that a larger eruption could result in an ashfall on Unalaska and its port, Dutch Harbor, which has a total population of about 4,000. But the main concern about Bogoslof, Dr. Coombs said, is its potential to affect aviation in what is a busy corridor for flights to and from Asia.

    Flying through volcanic ash can damage or destroy a plane’s engines, so if the eruption is big enough and the ash cloud is high enough, air travel can be shut down, as it was in much of Europe in April 2010 because of the eruption of Eyjafjallajökull, a volcano in Iceland.

    The Bogoslof eruptions are much smaller, and although warnings have been issued and some flights rerouted, so far there has been no need to shut down airspace over the Aleutians.

    See the full article here .

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  • richardmitnick 10:26 pm on December 20, 2016 Permalink | Reply
    Tags: , , MId-Atlantic Ridge, Mt Washington, Passive margin, Volcanoes   

    From Wired: “New England Might Not Be Volcano-Free Forever” 

    Wired logo

    Wired

    1
    Mt. Washington in the White Mountains of New Hampshire. Jose Azel/Getty Images

    Last week I ran across a fairly provocatively-titled article on Gizmodo that claimed that New Hampshire might have a volcanic future. At first glance, you might think that is click-bait nonsense, but that is far from it. At some point in the geologic future—maybe millions to hundreds of millions of years from now—volcanoes will erupt across eastern North America. It is likely inevitable. However, until recently, we haven’t had any geologic evidence of what might (and I emphasize might) be the first sparks that could someday lead to a newly volcanic New England.

    Now, New Hampshire and all of the northeastern United States has been a very volcanically quiet place for a long time—and by that, I mean we likely haven’t had a whiff of volcanism in over 100 million years (contrary to some apocryphal reports of volcanoes in the 1800s). That’s because all of New England is on what is called a “passive margin” of the North American continent. There is really nothing geologically exciting in terms of volcanoes or earthquakes along the whole east coast.

    Compare that to the “active margin” on the west coast, where you have the Cascade volcanoes, faults, earthquakes—the whole lot. That’s because on the west coast, North America is directly interacting with other tectonic plates, namely the Pacific, Gorda, and Juan de Fuca plates. These plates are either grinding against North America to make the San Andreas fault zone or plunging underneath the continent to create the Cascadia subduction zone.

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    USGS diagram of San Andreas Fault
    Date 14 March 2006
    Source http://nationalatlas.gov/articles/geology/features/sanandreas.html
    Author Kate Barton, David Howell, and Joe Vigil
    Permission USGS PD work

    3
    Cascadia subduction zone. CBS News

    Over on the east coast, you need to travel all the way to the middle of the Atlantic Ocean before you find another tectonic plate. That boundary between North America and Europe is a spreading ridge, where a new plate is created, moving the two continents further apart. The boundary is thousands of miles from the eastern seaboard of the continent, so it really plays no role in geologic activity along the passive eastern margin.

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    Mid-Atlantic Ridge. US Geological Survey image

    However, this will not always be the case. Although the Atlantic Ocean is geologically young and still actively spreading, it will start to close again at some point. Our current continental configuration on Earth is one where the continental plates are all fairly spread apart, but that is only one part of a tectonic cycle—the Wilson Cycle—in which massive supercontinents break into dispersed continents and assemble again. So, although North and South America are moving away from Europe and Africa today, at some point they will start to converge again.

    Subduction Isn’t That Subdued

    Why might that happen? Well, mostly likely it would be the initiation of a new subduction zone on one or both sides of the Atlantic Ocean. Remember, in a subduction zone, the dense oceanic plate (the floor of the Atlantic) will sink down underneath the more buoyant continent. Then we’ll start seeing the earthquakes and volcanoes associated with subduction.

    Of course, one of the biggest questions in tectonics today is what causes subduction to start. We’ve never seen it happen—the process likely takes millions of years. Exactly why a perfectly happy stable continental margin (like we have on the east coast of North America) suddenly starts to see the oceanic plate founder and subduction begin is the realm of arm-waving and speculation.

    See the full article here .

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