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  • richardmitnick 7:36 am on November 2, 2017 Permalink | Reply
    Tags: , Bárðarbunga is also a subglacial stratovolcano, Bárðarbunga on Iceland, , The pressure of magma in the magma chamber is increasing, Volcanoes   

    From Science Alert: “Iceland’s Biggest Volcano Is Getting Ready to Erupt Again” 

    ScienceAlert

    Science Alert

    1
    (Paddy Scott/Shutterstock)

    2 NOV 2017
    MICHELLE STARR

    At least it’s easier to pronounce than Eyjafjallajökull.

    Earthquake rumbles under the Vatnajökull glacier in Iceland could be signs of an impending eruption by the country’s biggest volcano.

    Bárðarbunga, which stands 2,009 metres (6,591 ft) above sea level, is one of a number of volcanoes that geologists are carefully monitoring after a spate of recent earthquake activity – indicating that the pressure in the volcano is increasing.

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    Bárðarbunga. Pictures taken by Peter Hartree between 14.30 and 15.00 on September 4th 2014.

    “The reason for the earthquakes in this place is that the volcano Bárðarbunga is inflating, i.e. the pressure of magma in the magma chamber is increasing,” volcano expert Páll Einarsson at the University of Iceland told the Daily Star.

    “The volcano is clearly preparing for its next eruption, that may happen in the next few years. The earthquakes last week are just the symptoms of this process, they do not cause the volcano to erupt.”

    Bárðarbunga has been rumbling, he said, since February 2015 – when the volcano’s last eruption, beginning August 2014, ended. Prior to that event, the volcano had been causing earthquakes with increasing frequency since 2007 – and the eruption itself was preceded by a swarm of 1,600 eruptions within 48 hours.

    The 2014-2015 eruption of Bárðarbunga was relatively light in consequences compared to the earlier 2010 eruption of the smaller Eyjafjallajökull. A subglacial stratovolcano, Eyjafjallajökull’s modest-sized eruption caused unusual and disproportionate havoc.

    The heat of the volcano melted the ice cap, which caused floods. Then it spewed ash several kilometres into the atmosphere – where it was carried thousands of kilometres over Europe by the jet stream above.

    So thick and far-reaching was the ash that air travel all over Europe was disrupted for weeks after the eruption.

    Bárðarbunga is also a subglacial stratovolcano, and although a repeat of Eyjafjallajökull’s havoc is possible, it’s unlikely – as demonstrated by the volcano’s 2014-15 eruption.

    Disaster expert Simon Day of University College London told the Daily Star that Bárðarbunga “is statistically unlikely to do so.”

    There are other rumblings in Iceland too – earlier this year, Einarsson told the Iceland Monitor that four volcanoes were on the path to eruption sometime in the next few years.

    The other three are Grímsvötn, Hekla, and Katla – the latter of which is considered the most dangerous volcano in Iceland.

    But the world has also been waiting on an eruption from Katla for decades.

    The Iceland Meteorological Office is not concerned yet. All four volcanoes – in fact, most of the country’s volcanoes – are marked green under the aviation colour code map. This denotes that the volcanoes are “in a normal, non-eruptive state.”

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  • richardmitnick 8:27 am on October 30, 2017 Permalink | Reply
    Tags: , , Volcanoes,   

    From Science: “Yellowstone’s massive volcano could erupt more frequently than scientists thought” 

    ScienceMag
    Science Magazine

    Oct. 25, 2017
    Paul Voosen

    1
    iStock.com/kwiktor

    Some 630,000 years ago, the supervolcano beneath Yellowstone National Park in Wyoming recorded its last catastrophic eruption, forming a caldera that nearly spans the park’s width and belching a thick layer of ash, or tephra, across North America. But rather than a single event, Yellowstone may have erupted twice in a span of 270 years, new evidence from mud cores discovered off the coast of Santa Barbara, California, indicates. The cores, presented here today at the annual meeting of the Geological Society of America, were captured at the farthest extent of the ash’s reach, recorded as wisps of tephra in finely sedimented, ancient mud uplifted near the ocean floor. Most evidence of the Yellowstone eruption (the park’s Grand Prismatic geyser is pictured) is found on land in thick layers of compacted, weathered rock, which could have easily hidden the dual eruption, the researchers say. Both tephra layers also coincide with a stark temperature decline of 3°C, according to the core’s records of oxygen isotopes and fossilized plankton, with each episode lasting 100 years or more. If confirmed, the research could indicate that Yellowstone can recharge its eruptions much more quickly than typically thought—and that traditional views of volcanic winter, the period of cooling caused by a volcano’s reflective droplets and ash, fail to explain how a century of cooling could follow the eruptions.

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  • richardmitnick 11:36 am on October 18, 2017 Permalink | Reply
    Tags: , , , Volcanoes,   

    From NYT: “A Surprise From the Supervolcano Under Yellowstone” 

    New York Times

    The New York Times

    OCT. 10, 2017
    SHANNON HALL

    1
    The Grand Prismatic Spring in Yellowstone National Park, a large hot spring known for its vibrant coloration. Beneath the park is a powerful supervolcano which drives the spring and other geological activity. Credit Marie-Louise Mandl/EyeEm, via Getty Images.

    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.

    To reach that conclusion, Hannah Shamloo, a graduate student at Arizona State University, and her colleagues spent weeks at Yellowstone’s Lava Creek Tuff — a fossilized ash deposit from its last supereruption. There, they hauled rocks under the heat of the sun to gather samples, occasionally suspending their work when a bison or a bear roamed nearby.

    Ms. Shamloo later analyzed trace crystals in the volcanic leftovers, allowing her to pin down changes before the supervolcano’s eruption. Each crystal once resided within the vast, seething ocean of magma deep underground. As the crystals grew outward, layer upon layer, they recorded changes in temperature, pressure and water content beneath the volcano, much like a set of tree rings.

    “We expected that there might be processes happening over thousands of years preceding the eruption,” said Christy Till, a geologist at Arizona State, and Ms. Shamloo’s dissertation adviser. Instead, the outer rims of the crystals revealed a clear uptick in temperature and a change in composition that occurred on a rapid time scale. That could mean the supereruption transpired only decades after an injection of fresh magma beneath the volcano.

    The time scale is the blink of an eye, geologically speaking. It’s even shorter than a previous study that found that another ancient supervolcano beneath California’s Long Valley caldera awoke hundreds of years before its eruption. As such, scientists are just now starting to realize that the conditions that lead to supereruptions might emerge within a human lifetime.

    “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,” said Ms. Shamloo, though she warned that there’s more work to do before scientists can verify a precise time scale.

    Kari Cooper, a geochemist at the University of California, Davis who was not involved in the research, said Ms. Shamloo and Dr. Till’s research offered more insights into the time frames of supereruptions, although she is not yet convinced that scientists can pin down the precise trigger of the last Yellowstone event. Geologists must now figure out what kick-starts the rapid movements leading up to supereruptions.

    “It’s one thing to think about this slow gradual buildup — it’s another thing to think about how you mobilize 1,000 cubic kilometers of magma in a decade,” she said.

    As the research advances, scientists hope they will be able to spot future supereruptions in the making. The odds of Yellowstone, or any other supervolcano, erupting anytime soon are small. But understanding the largest eruptions can only help scientists better understand, and therefore forecast, the entire spectrum of volcanic eruptions — something that Dr. Cooper thinks will be possible in a matter of decades.

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  • richardmitnick 1:06 pm on October 16, 2017 Permalink | Reply
    Tags: , , , , Volcanic Unrest at Mauna Loa Earth’s Largest Active Volcano, Volcanoes   

    From Eos: “Volcanic Unrest at Mauna Loa, Earth’s Largest Active Volcano” 

    AGU bloc

    AGU
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    Eos

    Weston Albert Thelen
    Asta Miklius
    Christina Neal

    Mauna Loa is stirring—is a major eruption imminent? Comparisons with previous eruptions paint a complicated picture.

    1
    Oblique aerial view looking north-northeast toward the summit area of Mauna Loa volcano (elevation 4,169 meters) on 15 January 1976. The summit caldera (Moku’āweoweo) is 6 kilometers long and 2.5 kilometers wide. The pit crater in the foreground marks the start of the Southwest Rift Zone. Mauna Kea volcano is on the skyline in the distance. Credit: D. Peterson, USGS

    Mauna Loa is showing persistent signs of volcanic unrest. Since 2014, increased seismicity and deformation indicate that Mauna Loa, the volcano that dominates more than half of the island of Hawaiʻi, may be building toward its first eruption since 1984.

    Thousands of residents and key infrastructure are potentially at risk from lava flows, so a critical question is whether the volcano will follow patterns of previous eruptions or return to its now historically unprecedented 33-year slumber.

    Mauna Loa has erupted 33 times since 1843, an average of one eruption every 5 years [Trusdell, 2012]. Typical of shield-building Hawaiian volcanoes, Mauna Loa hosts a summit caldera and two rift zones, the Northeast Rift Zone (NERZ) and the Southwest Rift Zone (SWRZ; Figure 1, inset).

    Since the two most recent eruptions, in 1975 and 1984, monitoring by the U.S. Geological Survey’s Hawaiian Volcano Observatory has changed dramatically. Ground-based instruments continuously record signals from global navigation satellite systems (GNSS, of which GPS is one example), measuring the changing shape of the ground surface in near-real time, and interferometric synthetic aperture radar (InSAR) provides extensive spatial coverage of deformation. Seismic monitoring has also improved with the addition of more stations, increased data fidelity, and improved data analysis.

    More people live on the slopes of Mauna Loa now than in the 1970s and 1980s, so improvements in monitoring technology are of more than just academic interest.

    How does this recent period of unrest compare with the periods just before previous eruptions? How reliable are these comparisons in predicting the next eruption?

    2
    Fig. 1. The Italian satellite system COSMO-SkyMed acquired radar images of Mauna Loa on 1 January 2013 and 30 April 2017 to produce this ascending mode interferogram. Each fringe represents 1.5 centimeters of motion in the line-of-sight direction to the satellite. The butterfly pattern of fringes suggests an inflating tabular body beneath the caldera and uppermost Southwest Rift Zone (see inset map). The sizes of the white dots represent the magnitudes of earthquakes that occurred during this period. The arrow at the bottom left shows the direction of the satellite’s motion. The satellite’s interferometric synthetic aperture radar (InSAR) antenna looks to the right of the satellite track, and the radar contacts the land surface at about 35° off vertical. The inset is a digital elevation map of Mauna Loa showing lava flows since 1843 in red. The box shows the approximate extent of the interferogram image. COSMO-SkyMed data were provided by the Agenzia Spaziale Italiana via the Hawaiʻi Supersite.

    The Current Unrest

    Several periods of unrest have occurred at Mauna Loa since the 1984 eruption. The shallow magma storage complex started refilling (inflating) immediately following the eruption, but inflation soon slowed, and stopped altogether in the mid-1990s (Figure 2). A short-lived inflation episode began in 2002 [Miklius and Cervelli, 2003], and another began in 2004. By 2009, inflation had largely ceased. Unlike the current unrest, these previous two inflation episodes were not associated with significant numbers of shallow earthquakes; rather, they started with brief periods of deep seismicity approximately 45 kilometers beneath the surface [Okubo and Wolfe, 2008].

    3
    Fig. 2. Changes in distance across Moku’āweoweo, Mauna Loa’s summit caldera, and earthquakes shallower than 15 kilometers from 1973 through April 2017 in the same area as Figure 1. Because today’s sensitive instruments can detect earthquakes that previous instruments would have missed, only earthquakes greater than M1.7 are plotted. Large, abrupt extensions are associated with the formation of volcanic dikes during the 1975 and 1984 eruptions; other extensions are mostly due to accumulation of magma in shallow reservoirs. Note that this distance change is not sensitive to extension across the upper SWRZ, where most of the magma accumulation occurred between October 2015 and mid-2016. (EDM is electronic distance measuring, and MOKP and MLSP are GPS instrument sites.)

    The current unrest started in earnest in 2014 (Figure 2). Seismicity rates began to rise above background levels as early as March 2013, and by summer 2014, both seismicity and deformation rates had increased significantly. The pattern of ground deformation indicated inflation of a magma storage complex beneath the caldera and uppermost SWRZ, areas that were also the most seismically active (Figure 3).

    Beneath the caldera, seismicity consists of mostly small earthquakes (magnitude M of less than 2.5) at depths of 2–3 kilometers. These earthquakes occur in swarms lasting days to weeks, separated by months of minor activity. Event rates have been as high as 15 earthquakes per hour, with most earthquakes too small to be formally located.

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    Fig. 3. Blue arrows (with gray 95% confidence error ellipses) show the average horizontal velocities of GNSS stations on Mauna Loa from mid-2014 through 2016. Red arrows represent velocities predicted by a model of a horizontally opening tabular body extending from about 3 to 6 kilometers beneath the summit and upper Southwest Rift Zone and a radially expanding body at about 3 kilometers beneath the southeastern wall of the caldera. The surface projections of these magma reservoirs are indicated by the black line and black circle. The average rate of magma accumulation in these shallow reservoirs is on the order of 13 million cubic meters per year.

    The uppermost SWRZ has been the most seismically active region during the current unrest, in terms of overall energy release and number of earthquakes. These earthquakes are typically 3–4 kilometers below the surface. Another area of seismicity has been high on the west flank of the volcano, where swarms of small earthquakes (mostly less than M2.5) at an average depth of about 7 kilometers typically last days to a week.

    In addition to shallow seismicity, there have been several deep (greater than 20 kilometers), long-period earthquakes loosely scattered beneath the summit area. During previous periods of inflation, earthquakes with similar characteristics have been associated with magma ascent [Okubo and Wolfe, 2008].

    Short-term rates of seismicity and deformation have varied in magnitude, with weeklong to monthlong periods of relative quiescence interspersed within longer-term trends of heightened activity. Although there is general long-term correlation between deformation and seismicity rates, there is no obvious relationship between them in the short term.

    The spatial pattern of deformation and seismicity has also varied. In fall 2015, after several months of decreased inflation at the summit, seismicity beneath the caldera largely ceased, and inflation in the upper SWRZ increased (Figure 4). In May 2016, inflation and seismicity beneath the caldera slowly resumed, but as of mid-2017, rates are low compared with those seen prior to fall 2015.

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    Fig. 4. COSMO-SkyMed ascending mode interferograms show the shift in locus of inflation toward the upper Southwest Rift Zone in October 2015. Each image covers about the same length of time: (left) 18 March 2015 to 9 August 2015 and (right) 24 July 2015 to 31 December 2015. Each full-color cycle represents 1.5 centimeters of motion in the line-of-sight direction toward the satellite. Arrow shows direction of motion of the satellite. The SAR antenna looks to the right of the satellite track; the incidence angle is about 35° off vertical. COSMO-SkyMed data were provided by the Agenzia Spaziale Italiana via the Hawaii Supersite.

    Comparison with Past Eruptions

    Deformation monitoring networks in place before the 1975 and 1984 eruptions were sufficient to provide long-term indications of inflation that along with increased seismicity, led to a general forecast for the 1984 eruption [Decker et al., 1983]. However, measurements were not frequent enough to evaluate whether there were precursory changes in extension or uplift in the summit area just prior to eruption.

    Direct comparison of magma storage geometries and volumes derived from deformation patterns is also not possible because of the limited spatial and temporal extent of the early geodetic monitoring networks. Pre-1984 measurements are consistent with, but cannot confirm, the existence of a large-volume tabular storage complex (a vertical, dikelike body) beneath the summit and upper SWRZ, similar to what we currently model from GNSS and InSAR data.

    Similarly, differences in seismic network sensitivity and data processing preclude direct comparison of current seismicity rates with pre-1975 and pre-1984 rates. Patterns in the locations of earthquakes stronger than about M1.7, however, are comparable, and these patterns show a clear coincidence between the locations of seismicity during the current unrest and previous preeruption patterns (Figure 5).

    Another approach to comparing precursory seismicity is to evaluate cumulative seismic energy release, which mainly reflects energy released by larger-magnitude earthquakes (energy release increases logarithmically with respect to earthquake magnitude). Between 1 May 2013 and 30 April 2017, energy release on the west flank was equivalent to an M4.1 earthquake. For the same region, energy releases during the 4 years prior to the 1975 and 1984 eruptions were M4.2 and M4.5, respectively. In the caldera and uppermost SWRZ, the current energy release sums to M4.4, compared with M4.9 and M4.4 for the 1975 and 1984 precursory periods.

    Thus, the energy released during the current 4 or so years of unrest is approaching that released during the 4 years prior to the 1975 and 1984 eruptions. In some volcanic systems, the amount of energy release compared with previous eruptions may be an indicator of whether a period of unrest results in an eruption [Thelen et al., 2010], but this relationship has not been established on shield volcanoes such as Mauna Loa.

    One to 2 years prior to the 1975 and 1984 eruptions, swarms of small earthquakes increased in intensity. The strongest swarms included hundreds of small earthquakes per day for weeks. Bursts, as they were called, were separated by 3–6 months of relative quiet [Koyanagi et al., 1975]. Recently, swarms on the west flank have increased in number and size, but the durations of the swarms are less than pre-1975 and 1984 levels. Similarly, swarms of tiny earthquakes beneath the caldera have not occurred at rates seen in the months prior to the 1975 and 1984 eruptions.

    Interestingly, during the days to weeks prior to the past two eruptions, the number of small earthquakes fluctuated instead of building up steadily, even reaching relatively low rates for short periods prior to eruption [Koyanagi, 1987; Lockwood et al., 1987]. However, both eruptions had distinct short-term seismic precursors. The 1975 eruption was preceded by less than an hour of strong tremor in the summit caldera area [Lockwood et al., 1987]. In 1984, small (less than M0.1) earthquakes increased in frequency, shaking the ground two or three times per minute about 2.5 hours before the eruption [Koyanagi, 1987]. Harmonic tremor began about 2 hours prior to eruption, with a large increase in tremor amplitude and a swarm of earthquakes 30 minutes prior to eruption. Seven earthquakes larger than M3 occurred during a period from 30 minutes before the 1984 eruption until just over 1 hour after the onset of the eruption.

    5
    Fig. 5. Earthquake epicenters for (a) the 4 years prior to the 1975 eruption, (b) the 4 years prior to the 1984 eruption, and (c) the latest 4 years of unrest (1 May 2013 to 30 April 2017). Earthquake symbol size is based on magnitude, and color is based on depth. Only earthquakes above M1.7 are included, in an attempt to compensate for differences in network sensitivity since 1975. All earthquakes are analyst reviewed. Because the analysis of earthquakes above M1.7 is only partially complete for the current episode of unrest, event rates since 2013 may actually be slightly higher than shown here.

    Is an Eruption in Our Near Future?

    Mauna Loa’s long history of observed activity aids in forecasting another eruption, but at present, any forecast still contains a high degree of uncertainty. Some aspects of the current unrest are similar to unrest prior to eruptions in 1975 and 1984. Earthquake locations, temporal behavior, and energy release suggest that the volcano may be following a similar pattern. Other aspects, however, differ from the periods prior to the 1975 and 1984 eruptions.

    During the current unrest period, we have not observed the kind of moderate to large flank earthquakes that preceded many historical eruptions [Walter and Amelung, 2006], including the 1975 and 1984 eruptions. Also, as of fall 2017, we have not seen the high rates of small earthquakes observed about 7–14 months prior to the 1975 and 1984 eruptions, even though our ability to detect them has improved. Thus, if current unrest follows previous patterns of seismicity, we may expect that the volcano is still many months from eruption.

    We must also consider that current unrest might not follow previous patterns, and an eruption could occur without months of elevated microseismicity. It is possible that after years of intermittent inflation, shallow magma storage is exerting pressures already near the breaking point of the overlying rock.

    We can’t say for certain whether there will be a precursory months-long increase in microseismicity before the next Mauna Loa eruption. However, an eruption will likely be immediately preceded by an hours-long, dramatic increase in small earthquakes (at least one earthquake per minute), strong tremor, and the occurrence of several M3 or stronger earthquakes, similar to the lead-up to the 1975 and 1984 eruptions. Real-time deformation data from tiltmeters and GNSS stations will show large anomalies as magma moves from storage reservoirs toward the surface to the eventual eruption site in the summit area and/or along one of the rift zones or (less likely) from radial vents on the west flank.

    It is also possible that current elevated rates of seismicity and deformation may not culminate in eruption anytime soon; rather, this could be yet another episode of unrest that gradually diminishes. During the 25-year repose between the 1950 and 1975 eruptions, seismic unrest in 1962, 1967, and 1970 did not lead to eruption, although in hindsight, each is considered a long-term precursor to the 1975 eruption [Koyanagi et al., 1975].

    The high rate of volcanic activity at neighboring Kīlauea volcano complicates assessing the likelihood of a Mauna Loa eruption in the coming months or years. Klein [1982] noted that longer repose intervals at Mauna Loa were statistically correlated with eruptive activity at Kīlauea. Indeed, the current long repose time at Mauna Loa is occurring at the same time as the long-lived Puʻu ʻŌʻō eruption at Kīlauea, which began in 1983 and continues today. Even so, the most recent eruption of Mauna Loa in 1984 occurred during this eruption at Kīlauea, so the impact of nearby volcanic activity on Mauna Loa’s behavior over short timescales is unknown.

    We can make one forecast with relative certainty: On the basis of nearly 200 years of documented activity, it is highly likely that the next eruption will begin in the summit region and then, within days to years, migrate into one of the two primary rift zones [Lockwood et al., 1987].

    It is important to note that seismicity and inflation beneath the uppermost SWRZ do not imply an increased likelihood of eruption along the SWRZ. Similar patterns of seismicity prior to the 1975 and 1984 eruptions did not result in sustained activity in the SWRZ. In 1984, the eruption began at the summit and migrated to the upper SWRZ before activity focused along the NERZ, suggesting that a magma body extending into the uppermost SWRZ—similar to that inferred from current data—was also active prior to that eruption.

    Communicating the Hazards

    In response to more than a year of persistently elevated rates of seismicity and deformation, the Hawaiian Volcano Observatory (HVO) elevated the Volcano Alert Level and Aviation Color Code for Mauna Loa to advisory/yellow on 17 September 2015, indicating that the volcano was restless and that monitoring parameters were above the long-term background levels.

    Since then, HVO has continued public education efforts and engaged agency partners, including Hawaiʻi County Civil Defense and the National Park Service, to discuss preparedness and response planning. In 2016, HVO installed new web cameras and upgraded real-time gas and temperature sensors in the summit caldera. Alarms have been set to alert scientists to significant changes in several data streams, including real-time seismic amplitude (a measure of seismic energy release), ground tilt, and satellite- and ground-based thermal imagery. Revised maps showing potential inundation zones and likely lava flow paths based on topography derived from digital elevation maps have been prepared.

    As with any precursory volcanic eruption sequence, it will be challenging to choose the correct time to alert authorities and elevate public concern about a possible eruption. Once an eruption has commenced, pinpointing the exact location of the outbreak—especially at night or in cloudy conditions—may not be straightforward and may require the use of new tools such as infrasound. Vent location determines which downslope areas are at greatest risk, so addressing this capability gap is a high priority.

    As of this writing, elevated rates of seismicity and deformation continue. Improvements in monitoring networks and alarming systems since 1984 put HVO in a better position to provide early warning and, once an eruption has commenced, help guide emergency response. Additional efforts to inform and prepare the public for the eventual eruption are an important step in minimizing impacts to life and property.

    References

    Decker, R. W., et al. (1983), Seismicity and surface deformation of Mauna Loa volcano, Hawaii, Eos Trans. AGU, 64(37), 545–547, https://doi.org/10.1029/EO064i037p00545-01.

    Klein, F. W. (1982), Patterns of historical eruptions at Hawaiian volcanoes, J. Volcanol. Geotherm. Res., 12, 1–35, https://doi.org/10.1016/0377-0273(82)90002-6.

    Koyanagi, R. Y. (1987), Seismicity associated with volcanism in Hawaii: Application to the 1984 eruption of Mauna Loa volcano, U.S. Geol. Surv. Open File Rep., 87-277, 76 pp.

    Koyanagi, R. Y., E. T. Endo, and J. S. Ebisu (1975), Reawakening of Mauna Loa volcano, Hawaii: A preliminary evaluation of seismic evidence, Geophys. Res. Lett., 2(9), 405–408, https://doi.org/10.1029/GL002i009p00405.

    Lockwood, J. P., et al. (1987), Mauna Loa 1974–1984: A decade of intrusive and extrusive activity, in Volcanism in Hawaii, chap. 19, U.S. Geol. Surv. Prof. Pap., 1350, 537–570.

    Miklius, A., and P. Cervelli (2003), Interaction between Kīlauea and Mauna Loa, Nature, 421, 229, https://doi.org/10.1038/421229a.

    Okubo, P. G., and C. J. Wolfe (2008), Swarms of similar long-period earthquakes in the mantle beneath Mauna Loa volcano, J. Volcanol. Geotherm. Res., 178, 787–794, https://doi.org/10.1016/j.jvolgeores.2008.09.007.

    Thelen, W. A., S. D. Malone, and M. E. West (2010), Repose time and cumulative moment magnitude: A new tool for forecasting eruptions?, Geophys. Res. Lett., 37, L18301, https://doi.org/10.1029/2010GL044194.

    Trusdell, F. A. (2012), Mauna Loa—History, hazards, and risk of living with the world’s largest volcano, U.S. Geol. Surv. Fact Sheet, 2012-3104, 4 pp., https://pubs.usgs.gov/fs/2012/3104/.

    Walter, T. R., and F. Amelung (2006), Volcano-earthquake interaction at Mauna Loa volcano, Hawaii, J. Geophys. Res., 111, B05204, https://doi.org/10.1029/2005JB003861.

    Author Information

    Weston Albert Thelen (email: wthelen@usgs.gov), Cascade Volcano Observatory, U.S Geological Survey, Vancouver, Wash.; and Asta Miklius and Christina Neal, Hawaiian Volcano Observatory, U.S. Geological Survey, Hawaiʻi National Park, Hawaii

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  • richardmitnick 2:33 pm on October 10, 2017 Permalink | Reply
    Tags: , , , Ritter Island, , Volcanic islands are the source of some of the world’s largest landslides, Volcanoes   

    From Eos: “An 1888 Volcanic Collapse Becomes a Benchmark for Tsunami Models” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    10.10.17
    Aaron Micallef
    Sebastian F. L. Watt
    Christian Berndt
    Morelia Urlaub
    Sascha Brune
    Ingo Klaucke
    Christoph Böttner
    Jens Karstens
    Judith Elger

    1
    Scientists aboard the R/V Sonne (shown here) profiled the seafloor and subsurface structures near Ritter Island, north of New Guinea, in 2016. A large portion of this volcanic island collapsed and slid into the sea in 1888, making it an ideal case study for modeling volcanic collapse landslides and the tsunamis they generate. Credit: Christian Berndt

    Early one March morning in 1888, a 4-cubic-kilometer chunk of the Ritter Island volcano collapsed into the Bismarck Sea northeast of New Guinea. This volume of land was about twice that of the Mount St. Helens landslide in 1980, and it is the largest historically recorded tsunami-causing volcanic sector collapse.

    The ensuing landslide triggered a tsunami tens of meters high. The waves were still 8 meters high when they reached parts of the island of New Guinea that are several hundreds of kilometers away, according to observers who witnessed the event [Ward and Day, 2003].

    Volcanic islands are the source of some of the world’s largest landslides. These landslides have the potential to generate large tsunamis. Scientists have debated the magnitude of these tsunamis, but much uncertainty remains over landslide dynamics and how far a tsunami can travel across an ocean basin while remaining large enough to cause damage.

    Studies of Ritter Island’s landslide and ensuing tsunami could significantly reduce that uncertainty. During a 6-week-long expedition in November and December 2016 aboard the German R/V Sonne, we mapped the Ritter Island collapse scar and deposit using hull-mounted multibeam sonar systems, which produced high-resolution bathymetry (Figure 1) and acoustic backscatter data.

    We are using data from this expedition, alongside a range of direct observations and samples, to generate a detailed interpretation of the Ritter Island landslide. With these robust field data, we set the stage for testing coupled landslide-tsunami models.

    An Ideal Study Site

    Ritter Island’s historic landslide, along with a heightened awareness of tsunami hazards following several recent devastating events, has caused some to wonder if other volcanic islands could experience flank or total collapse and, if so, how far tsunamis could reach. One hypothetical scenario that captured the attention of the popular media in 2004 involves a potential collapse of the Cumbre Vieja volcano on the southern half of the island of La Palma, one of the Canary Islands off the northwest coast of Africa.

    Such a collapse could trigger a tsunami that races across the Atlantic Ocean. However, recent tsunami models span an order of magnitude in their predictions of far-field wave heights for the La Palma collapse scenario.

    Resolving such discrepancies in our understanding of landslide and tsunami processes requires a field data set in which both phenomena can be observed to test current models. The sector collapse of Ritter Island, Papua New Guinea, in 1888 meets both these criteria.

    The landslide generated a tsunami that devastated shorelines as far as 600 kilometers away [Day et al., 2015]. An important factor is that there are eyewitness observations of the tsunami height, arrival time, and frequency at a range of locations around the Bismarck Sea [Day et al., 2015]. The event can thus be used as a benchmark for testing models of landslide-generated tsunamis if the volume, distribution, and dynamics of the landslide mass can be reconstructed.

    2
    Fig. 1. (a) Three-dimensional view of the Bismarck Sea between Umboi and Sakar islands compiled using data from the SO-252 multibeam echo sounder, bathymetric data from the General Bathymetric Chart of the Oceans (GEBCO), and altimetry from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite. The gray transparent cone represents Ritter Island before the 1888 event. Black lines and the red box indicate 2-D and 3-D seismic reflection data, respectively, acquired during the SO-252 expedition. The white arrows here and below indicate the direction of material mobilization during the 1888 event. (b) Three-dimensional reflection seismic data (from the area in the red box above) showing the Ritter Island deposit, remnant block, and parasitic volcanic cone. No image credit.

    Geological Setting

    Ritter Island is located north of Australia in the Bismarck Sea about 80 kilometers north of New Guinea and some 20 kilometers off the western end of New Britain. Situated between the islands of Umboi and Sakar (Figure 1), it forms part of the Bismarck Volcanic Arc, which results from the northward subduction of the Solomon Plate underneath the Bismarck Plate [Baldwin et al., 2012]. Today, Ritter Island is a narrow, crescent-shaped island, around 1.2 kilometers long and 200 meters wide, reaching an elevation of approximately 140 meters above sea level.

    This island is all that remains of a larger, steep-sided conical island that was around 750 meters high before it collapsed in 1888 [Day et al., 2015]. During the 19th century, Ritter Island was known among navigators in the region as a highly active volcano, characterized by frequent Strombolian activity [Johnson, 2013].

    There is evidence for several submarine eruptions since 1888 that have constructed a cone with a current summit around 200 m beneath sea level. The remnant of the island above the waterline is dominated by interbedded sequences of basaltic scoria and thin lava flows that are consistent with low-level Strombolian activity.

    3
    This arc is all that remains of the Ritter Island volcanic cone. Underwater deposits show clear evidence of the landslide triggered by the collapsing cone, and eyewitness accounts described the resulting tsunami. Credit: Christian Berndt.

    Contemporary observations of the tsunami triggered by the 1888 event suggest a single wave train, which is consistent with one main phase of landslide movement and tsunami generation [Day et al., 2015]. The landslide deposit is young enough to be preserved at the seafloor without significant overlying sedimentary cover, so it can be examined today to understand the emplacement dynamics of a large volcanic island landslide.

    Volcanic island landslides with volumes of 1 to 10 cubic kilometers, such as the Ritter Island landslide, have a global recurrence interval of 100 to 200 years [Day et al., 2015]. Therefore, a similar event is likely to occur in the next 100 years, in contrast to the extremely large ocean island collapses (e.g., Canary Islands and Lesser Antilles) that have recurrence intervals of tens of thousands of years or more.

    Collecting the Field Data Set

    During our 2016 expedition, we used a Parasound subbottom profiler with 10-centimeter resolution, as well as 2-D multichannel seismic data and P-Cable 3-D reflection seismic data acquisition systems to image the collapse deposit with 5-m vertical and horizontal resolution (Figure 1). Additional observations and samples collected across the deposit and island flanks, using towed video cameras and sediment samplers, provide ground truthing of the geophysical data and allow us to construct a detailed interpretation of landslide emplacement processes.

    The acquired data show the three-dimensional structure of the Ritter Island landslide deposit and enabled us to reconstruct the kinematics of the emplacement process. The new data set will be used to do the following:

    quantify the overall volume of the material that has been mobilized
    decipher the nature and extent of landslide disintegration
    determine the location, distribution, and size of transported blocks
    identify the nature and origin of different regions of the landslide deposit
    understand the relationship between landslides and the eruption history of Ritter Island and surrounding volcanoes

    These are key parameters for determining the landslide failure and emplacement process and the dynamics of the 1888 tsunami. An initial assessment of the data indicates that the flanks of Ritter Island below sea level expose clastic sequences similar to those in the scar above the water, with an increase in more massive lava units in the lowermost part of the edifice. The landslide cuts deeply into the island structure, and the scar exposures suggest an edifice that is dominated by loosely compacted layers of volcanic rock fragments.

    The landslide mass split and flowed around a remnant block of the island and dispersed within the channel between Umboi and Sakar (Figure 1), where it formed a deposit that is relatively flat at the margins and has irregular channelization in the central part. Parts of the landslide deposit traveled through a constriction between Umboi and Sakar and incorporated underlying seafloor sediment.

    A Framework for Future Models

    Our observations indicate that minor changes in slope gradient can strongly affect landslide dynamics. The deposition of the Ritter landslide entailed a progressive, multiphase, brittle to plastic failure that mobilized material over a considerable distance. The distal deposit, near the leading edge of the landslide, incorporates a major proportion of underlying seafloor sediment.

    Seismic profiles through the distal deposit indicate that the 1888 landslide was only the latest of a series of large-volume volcanic landslides from the surrounding islands. Some blocks piercing the seafloor are, in fact, rooted within older and much larger landslide deposits.

    How large a tsunami a volcanic collapse landslide of a given size will generate and how far the tsunami will travel before it dissipates remain open questions. The information we gathered on this expedition will provide the framework for coupled landslide-tsunami models, which are required to assess the destructive potential of sector collapse–related tsunamis.
    Acknowledgments

    This work reflects the joint effort of the SO252 expedition’s shipboard scientific party. We thank Simon Day, Eli Silver, and Russell Perembo for sharing data and helping with the survey planning. We thank the master and crew of R/V Sonne and our technicians for support during the cruise. Data collection was funded through the BMBF project Ritter Island 03G0252A. A.M. acknowledges funding from the European Research Council under the European Union’s Horizon 2020 Programme (MARCAN, grant agreement 677898).

    References

    Baldwin, S. L., P. G. Fitzgerald, and L. E. Webb (2012), Tectonics of the New Guinea region, Annu. Rev. Earth Planet. Sci., 40, 495–520, https://doi.org/10.1146/annurev-earth-040809-152540.

    Day, S., et al. (2015), Submarine landslide deposits of the historical lateral collapse of Ritter Island, Papua New Guinea, Mar. Pet. Geol., 67, 419–438, https://doi.org/10.1016/j.marpetgeo.2015.05.017.

    Johnson, R. (2013), Fire Mountains of the Islands: A History of Volcanic Eruptions and Disaster Management in Papua New Guinea and the Solomon Islands, ANU Press, Acton, Australia, https://doi.org/10.26530/OAPEN_462202.

    Ward, S. N., and S. Day (2003), Ritter Island volcano—Lateral collapse and the tsunami of 1888, Geophys. J. Int., 154, 891–902, https://doi.org/10.1046/j.1365-246X.2003.02016.x.

    Author Information

    Aaron Micallef, Marine Geology and Seafloor Surveying group, University of Malta, Msida; Sebastian F. L. Watt, School of Geography, Earth and Environmental Sciences, University of Birmingham, U.K.; Christian Berndt (email: cberndt@geomar.de) and Morelia Urlaub, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany; Sascha Brune, GFZ German Research Centre for Geosciences, Potsdam; and Ingo Klaucke, Christoph Böttner, Jens Karstens, and Judith Elger, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
    Citation: Micallef, A., S. F. L. Watt, C. Berndt, M. Urlaub, S.Brune, I. Klaucke, C. Böttner, J. Karstens, and J. Elger (2017), An 1888 volcanic collapse becomes a benchmark for tsunami models, Eos, 98, https://doi.org/10.1029/2017EO083743. Published on 10 October 2017.

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  • richardmitnick 12:27 pm on October 10, 2017 Permalink | Reply
    Tags: , , Volcanoes, Volcanologists lose their lives in pursuit of knowledge   

    From U Bristol via COSMOS: “Volcanologists lose their lives in pursuit of knowledge” 

    University of Bristol

    COSMOS

    10 October 2017
    Andrew Masterson

    Death records show scientists and tourists at risk of death in eruptions.

    1
    A village destroyed by pyroclastic density currents in the 2010 eruption of Merapi, Indonesia. Over 350 people lost their lives, but successful evacuations saved many thousands. Susanna Jenkins.

    Scientists are among the groups of people most likely to be killed in a volcanic eruption, new research has shown.

    A team led by Sarah Brown of the School of Earth Sciences at the UK’s University of Bristol tracked down and compiled some 635 documents spanning the years 1500 CE to 2017, which collectively catalogued 278,368 volcano-linked fatalities. The death records, drawn from academic papers and press reports, included deaths caused by lava, projectiles flung from erupting volcanoes, pyroclastic flows, mudslides and ash clouds.

    Brown’s team also combed the reports for information relating to how far away from the volcano each fatality occurred, and, where available, the occupation of the person concerned. Previously existing records contained location data for only 5% of recorded deaths; the latest work, published in Journal of Applied Volcanology, ups that to 72%.

    The team found that almost half of all eruption-related deaths happened within 10km of a volcano, but at least one was recorded 170km away.

    Volcano ballistics – rocks flung into the air – were the most common cause of death within five kilometres of a summit, with pyroclastic flows accounting for most of those occurring between five and 15 kilometres away. Ash clouds were responsible for the majority of deaths further away.

    Most victims across the centuries, not surprisingly, were people who lived on or near volcanoes. Specific types of non-residents, however, stood out for being at greatest risk, namely tourists, emergency service personnel, journalists and scientists.
    A total of 561 tourists were killed, mostly within a five kilometre radius, and predominantly by flying rocks. These occurred mainly as a result of very sudden eruptions, affecting visitors who thought the volcano was inactive.

    The next most common group of fatalities were scientists – mainly volcanologists who were standing within one kilometre of a crater, doing research at the time. Brown’s group found 67 such death records, compared to 57 for first responders and 30 for media.

    Brown hopes the data will lead to improved management strategies around volcanoes, which could save lives.

    “While volcanologists and emergency response personnel might have valid reasons for their approach into hazardous zones, the benefits and risks must be carefully weighed,” she says.

    “The media and tourists should observe exclusion zones and follow direction from the authorities and volcano observatories.”

    “Tourist fatalities could be reduced with appropriate access restrictions, warnings and education.”

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    Bristol is one of the most popular and successful universities in the UK and was ranked within the top 50 universities in the world in the QS World University Rankings 2018.

    The University of Bristol is at the cutting edge of global research. We have made innovations in areas ranging from cot death prevention to nanotechnology.

    The University has had a reputation for innovation since its founding in 1876. Our research tackles some of the world’s most pressing issues in areas as diverse as infection and immunity, human rights, climate change, and cryptography and information security.

    The University currently has 40 Fellows of the Royal Society and 15 of the British Academy – a remarkable achievement for a relatively small institution.

    We aim to bring together the best minds in individual fields, and encourage researchers from different disciplines and institutions to work together to find lasting solutions to society’s pressing problems.

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  • richardmitnick 10:10 am on September 27, 2017 Permalink | Reply
    Tags: , Drone Peers into Open Volcanic Vents, , Fortunately robotic technology can go where humans cannot, , UAVs-Unmanned aerial vehicles, Volcanoes   

    From Eos: “Drone Peers into Open Volcanic Vents” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    9.27.17
    Nicolas Turner, Bruce Houghton, Jacopo Taddeucci, Jost von der Lieth, Ullrich Kueppers, Damien Gaudin, Tullio Ricci, Karl Kim, and Piergiorgio Scalato

    1
    Stromboli, one of the world’s most active volcanoes, ejects large, hot volcanic bombs in this long-exposure image of the northeastern region of the summit crater terrace. During a May 2016 pilot project, the authors sent unmanned aerial vehicles where humans couldn’t go to capture images and gather data on the locations and characteristics of Stromboli’s craters and vents. Credit: Rainer Albiez/Shutterstock.com

    Volcanoes that erupt frequently give researchers special opportunities to make repeated high-resolution observations of rapid eruption processes. At explosive volcanoes like Stromboli, situated just off the southwestern coast of Italy, “normal” explosive eruptions take place every few minutes to tens of minutes. However, the rainout of hot volcanic bombs, some as large as a meter across, makes it hazardous for scientists and their instruments to get close enough to Stromboli’s active vents to collect some forms of essential data.

    At volcanoes like Stromboli, we can make many key observations from safe locations, hundreds of meters from the erupting vents. Other key observations must be made from locations beside or immediately above the vents. These underrecorded observations include the exact locations of vents, their dimensions, and the depth to the magma’s free surface. These observations have generally not been feasible because explosions occur at irregular frequencies, and they seldom provide warning; our inability to make these observations has been a major impediment to our models of the eruption process.

    Fortunately, robotic technology can go where humans cannot. Unmanned aerial vehicles (UAVs) have become cheaper and more accessible, and they now have the ability to carry lightweight optical sensors for mapping and aerial observations of volcanic activity.

    2
    Fig. 1. (top) Digital point cloud model of Stromboli crater terrace showing the two vent areas of the crater terrace. (middle) Digital elevation models (DEMs) of the northeast and southwest vent areas showing morphology. (bottom) Classification maps of active vents, inactive vents, and fumaroles from the high-resolution DEMs, aerial imagery, and low-altitude video observations of activity for active vents and fumaroles. Inactive vents were identified by examining the DEMs for features with morphology similar to that of the active vents.

    We used a UAV in a May 2016 pilot survey campaign at Stromboli to map detailed features of the active crater terrace and produce a high-resolution digital elevation model, with details as small as about 5 centimeters. Different vent areas within this crater terrace host active and inactive vents as well as fumaroles, and the UAV helped us determine their locations and dimensions.

    What We Do Know

    There are many things scientists can observe from volcanoes without drones. For example, remote observations from closely positioned cameras and sensors can record initial velocities for the erupted particles (bombs and ash) [Patrick et al., 2007; Gaudin et al., 2016], event durations and mass eruption rates [Taddeucci et al., 2012; Rosi et al., 2013; Gaudin et al., 2014], temperature and flux of gas species [Burton et al., 2007], and the sizes of the ejected bombs [Gurioli et al., 2013; Bombrun et al., 2015 (sorry, no links)].

    3
    Fig. 2. A sudden shift in wind direction momentarily sweeps away a gas cloud, giving the UAV a clear view of the interior of the crater and revealing an active vent (2) and an inactive vent (3). Active vent 1 is obscured, but it lies directly behind the bluish gas plume to the left of vent 2.

    Through recent field campaigns at Stromboli, scientists have gathered excellent time-synchronized databases of geophysical data and observations of eruption timings, pulsations, and mass flux derived from seismometers, high-speed cameras, webcams, Doppler radar, and infrasound sensors [e.g., Scarlato et al., 2014]. MultiGAS instruments (which combine optical and electrochemical sensors), Fourier transform infrared spectrometers, and ultraviolet and thermal infrared cameras have captured the nature and flux of key magmatic gases (water, carbon dioxide, and sulfur gases) associated with the activity.

    These sensors, however, have their limits. UAVs, however, can push data collection beyond these limits.

    Soaring Above the Danger

    Over the past 2 decades, Stromboli has been surveyed with lidar technology, but because of the high costs involved with lidar surveys, they are not conducted frequently enough to capture rapid changes at the summit of Stromboli.

    5
    Fig. 3. The UAV captured this visible-light still frame of an expanding ash-rich explosion from the dominant vent 4. The ash plume is more than 300 meters high.

    UAV-based mapping can supplement or replace lidar surveys. UAVs, popularly known as drones, were first used at Stromboli in 2007 to collect ash samples [Taddeucci et al., 2007]. Since that time, they have become cheaper, smarter, and able to carry higher-quality imaging sensors, such as the X5 camera mounted on the DJI Inspire-1 quadcopter for our 2016 study.

    Advances in the field of computer vision have also yielded software capable of extracting 3-D topography from multiple 2-D images in a process called structure from motion. Pairing this practical technique with UAVs has resulted in widespread adoption across multiple fields in science, and volcanology is no exception [James and Robson, 2012].

    UAVs, in combination with the live webcams deployed around the crater terrace [Fornaciai et al., 2010; Calvari et al., 2016], provide an unprecedented level of monitoring via imaging and sampling eruption plumes. UAVs could even be used to deploy sensors near or inside the vent.

    What’s more, with an extended range, UAVs could allow observations when human access to the summit is forbidden and dangerous. This capability would be especially useful, for example, during the rare paroxysmal phases, which can last several months.

    Given this potential, we decided to put the utility of UAVs to the test.

    First Results

    Even UAVs face challenges like constant gas emissions, high and gusting winds, and unpredictable explosions when mapping volcanic environments like Stromboli. In the worst case, UAVs may be severely damaged, or their data may be lost.

    During our 2016 campaign, explosions proved the most challenging to cope with: On more than one occasion, the UAV was almost engulfed by a rising ash plume while it was mapping directly above an active vent. Active fumaroles constantly sent up clouds of gas, condensed water vapor, and ash particles, making it difficult for the onboard camera to get clear images of these vents for use in mapping the interior of the source craters. Fortunately, shifts in wind would briefly clear the craters, providing the camera with an occasional clear view, as seen in the video below.


    During a May 2016 mapping survey, an unmanned aerial vehicle (drone) captured this close-up view of several active vents on the slopes of Stromboli, one of the world’s most active volcanoes, situated just off the southwestern coast of Italy. Stromboli often produces explosive eruptions every few minutes, making it too hazardous for researchers to approach these vents to take data. Credit: Nicolas Turner and coauthors.

    We constructed the final maps of the crater terrace (Figure 1) by selecting the highest-quality images from more than a dozen mapping flights over 2 days. We processed the images with structure from motion software to construct a relatively gas free orthomosaic (aerial map corrected for distortions) and accompanying digital elevation model.

    6
    Fig. 4. The UAV captured this image of vents 2 and 5 in the northeast and southwest regions, respectively, between explosions.

    We mapped a total of 4 active vents, 11 inactive vents, and 33 fumaroles in the southwest and northeast vent areas present in May 2016 (Figure 1). There is no clear pattern to vent distribution within the larger structures on the crater terrace. Inactive vents, particularly fumaroles, tend to occur in clusters without a single, consistent orientation. The two principal northeast vents are aligned approximately east–west and are 69 meters apart. The two principal southwest vents are 55 meters apart and aligned roughly north to south.

    Overall, the northeastern active vents were similar to each other in depth and diameter (Figure 2), but the southwestern active vents were significantly deeper. Inactive vents were much shallower than active vents. During a week of observations, the southwestern vents produced the larger and more powerful explosions. Explosions from vent 4 (see Figure 1) were typically ash charged, and the free surface was generally covered by debris between successive explosions. These plumes often reached heights of several hundred meters (Figure 3).

    In contrast, an incandescent free surface was often visible in vent 5 and the active northeastern vents (see Figure 4), and in Figure 5, spattering and outgassing are clearly visible in vent 2 during a repose interval.

    7
    Fig. 5. Close-up view of vent 2 showing weak discontinuous spattering activity that continued between explosions.

    Implications for Eruption Processes and Volcano Monitoring

    This pilot survey yielded useful data, and it serves as a guide for future more ambitious and repeated deployments. The data we gathered—the precise source locations of explosions, for example—can potentially help us reduce the uncertainty in geophysical model inputs for seismic and acoustic arrays and gravity measurements.

    We hope to establish precise correlations of changing eruption style and intensity with time for single vents, along with synchronous observations of depths to the free surface of magma in the parent vents. This and future deployments will help us to monitor abrupt and progressive changes in the diameter of single vents over time and the influence of these changes on eruptive behavior.

    8
    Near-infrared picture of a bomb-bearing explosion from vent 5. Light tones denote high (incandescent) temperatures. The vertical field of view is 20.5 meters.

    Our data will assist in making comparisons of how differences in vent width and depth to the free surface, the orientation and inclination of the conduit, and the extent of debris covering the free surface all influence contrasting eruption behavior at adjacent vents.

    The ability to capture such detail at an active volcano offers the opportunity to greatly enhance programs for short-term as well as long-term volcano monitoring. Scientists modeling Strombolian eruptions can use these new data to reduce the uncertainty in numerical model input parameters (e.g., conduit and acoustic modeling).

    The low cost and safety of UAV operations allow small-scale changes to be captured and UAV surveys to be launched as frequently as necessary. These benefits make UAVs a critical complement to other remote sensing and geophysical techniques.

    Acknowledgments

    This study was supported by funding from the National Science Foundation (NSF EAR14-27357) and the VERTIGO Marie Curie ITN, funded through the European Seventh Framework Programme (FP7 2007-2013) under grant agreement 607905. We acknowledge numerous companions during the 2016 campaign at Stromboli, especially Elisabetta del Bello, Valeria Cigala, Bianca Mintz, and Pierre-Yves Tournigand.

    References

    Bombrun, M., et al. (2015), Anatomy of a Strombolian eruption: Inferences from particle data recorded with thermal video, J. Geophys. Res. Solid Earth, 120, 2367–2387, https://doi.org/10.1002/2014JB011556.

    Burton, M., et al. (2007), Magmatic gas composition reveals the source depth of slug-driven Strombolian explosive activity, Science, 317, 227–230, https://doi.org/10.1126/science.1141900.

    Calvari, S., et al. (2016), Monitoring crater-wall collapse at active volcanoes: A study of the 12 January 2013 event at Stromboli, Bull. Volcanol., 78, 39, https://doi.org/10.1007/s00445-016-1033-4.

    Fornaciai, A., et al. (2010), A lidar survey of Stromboli volcano (Italy): Digital elevation model-based geomorphology and intensity analysis, Int. J. Remote Sens., 31, 3177–3194, https://doi.org/10.1080/01431160903154416.

    Gaudin, D., et al. (2014), Pyroclast tracking velocimetry illuminates bomb ejection and explosion dynamics at Stromboli (Italy) and Yasur (Vanuatu) volcanoes, J. Geophys. Res. Solid Earth, 119, 5384–5397, https://doi.org/10.1002/2014JB011096.

    Gaudin, D., et al. (2016), 3‐D high‐speed imaging of volcanic bomb trajectory in basaltic explosive eruptions, Geochem. Geophys. Geosyst., 17, 4268–4275, https://doi.org/10.1002/2016GC006560.

    Gurioli, L., et al. (2013), Classification, landing distribution, and associated flight parameters for a bomb field emplaced during a single major explosion at Stromboli, Italy, Geology, 41, 559–562, https://doi.org/10.1130/G33967.1.

    Harris, A. J. L., et al. (2013), Volcanic plume and bomb field masses from thermal infrared camera imagery, Earth Planet. Sci. Lett., 365, 77–85, https://doi.org/10.1016/j.epsl.2013.01.004.

    James, M. R., and S. Robson (2012), Straightforward reconstruction of 3D surfaces and topography with a camera: Accuracy and geoscience application, J. Geophys. Res., 117, F03017, https://doi.org/10.1029/2011JF002289.

    Patrick, M. R., et al. (2007), Strombolian explosive styles and source conditions: Insights from thermal (FLIR) video, Bull. Volcanol., 69, 769–784, https://doi.org/10.1007/s00445-006-0107-0.

    Rosi, M., et al. (2013), Stromboli volcano, Aeolian Islands (Italy): Present eruptive activity and hazards, Geol. Soc. London Mem., 37, 473–490, https://doi.org/10.1144/M37.14.

    Scarlato, P., et al. (2014), The 2014 Broadband Acquisition and Imaging Operation (BAcIO) at Stromboli Volcano (Italy), Abstract V41B-4813 presented at the 2014 Fall Meeting, AGU, San Francisco, Calif.

    Taddeucci, J., et al. (2007), Advances in the study of volcanic ash, Eos Trans. AGU, 88, 253, https://doi.org/10.1029/2007EO240001.

    Taddeucci, J., et al. (2012), High-speed imaging of Strombolian explosions: The ejection velocity of pyroclasts, Geophys. Res. Lett., 39, L02301, https://doi.org/10.1029/2011GL050404.

    Author Information

    Nicolas Turner (email: nrturner@hawaii.edu; @nicolasrturner) and Bruce Houghton, Department of Geology and Geophysics, University of Hawai‘i at Mānoa, Honolulu; Jacopo Taddeucci, Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy; Jost von der Lieth, Department of Earth Sciences, Universität Hamburg, Germany; Ullrich Kueppers and Damien Gaudin, Ludwig-Maximilians-Universität München, Munich, Germany; Tullio Ricci, Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy; Karl Kim, National Disaster Preparedness Training Center, University of Hawai‘i at Mānoa, Honolulu; and Piergiorgio Scalato, Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
    Citation: Turner, N., B. Houghton, J. Taddeucci, J. von der Lieth, U. Kueppers, D. Gaudin, T. Ricci, K. Kim, and P. Scalato (2017), Drone peers into open volcanic vents, Eos, 98, https://doi.org/10.1029/2017EO082751. Published on 27 September 2017.

    See the full article here .

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  • richardmitnick 10:46 am on May 29, 2017 Permalink | Reply
    Tags: , Cleveland Volcano, , , Volcanoes   

    From Science Times: “The Bogoslof Volcano Eruption In the Aleutian Islands In Alaska May Hamper The Activity Of The Flights” 

    Science Times

    Science Times

    May 29, 2017
    partha das

    1
    (Photo : NASA via Getty Images) In this photo provided by NASA, The eruption of the Cleveland Volcano is seen as photographed by an Expedition 13 crewmember on the International Space Station May 23, 2009 in the Aleutian Islands, Alaska. The Cleveland Volcano has erupted again yesterday sending a cloud of ash 15,000 feet into the sky according to reports on December 30, 2011.

    Mount Cleveland (also known as Cleveland Volcano) is a nearly symmetrical stratovolcano on the western end of Chuginadak Island, which is part of the Islands of Four Mountains just west of Umnak Island in the Fox Islands of the Aleutian Islands of Alaska.

    2
    From the USGS caption: Mount Cleveland forms the western half of Chuginadak Island in the central Aleutian Islands. This symmetrical, 1,730-m (5,676 ft)-high stratovolcano and has been the site of numerous eruptions in the last two centuries; the most recent eruption occurred in 1994. In 1944, a U.S. Army serviceman was reportedly killed by an eruption from Mount Cleveland.
    Date 24 July 1994
    Source http://pubs.usgs.gov/dds/dds-40/ (image 94 of Volcanoes of the Alaska Peninsula and Aleutian Islands—Selected Photographs)
    Author M. L. Harbin of the University of Alaska Fairbanks in a joint program, the Alaska Volcano Observatory, with the USGS[1]

    The eruption of the Bogoslof Volcano in the Aleutian Islands may disrupt the activity of the important flights. The Alaska Volcano has been active for the last six months.

    For the last six months, the Bogoslof Volcano has been active and the last eruption took place on Sunday at 2:16 pm, Global News reported. This Alaska Volcano is situated in the Aleutian Islands in Alaska. The Sunday eruption lasted for 55 minutes and this ultimately sent one ash cloud that was 10,668 meters high, the Alaska Volcano Observatory stated.

    The increasing amount of ash from the Bogoslof Volcano can be very harmful to the jet engines as it can stop the engines. Ash coming out from the volcano of the southwest Alaska possesses a great threat for the airlines. The threat becomes acute when the cloud crosses the height of 6,096 meters. The airlines between the North America and the Asia mainly face the crisis.

    The previous Aviation Color Code was red after the Bogoslof Volcano eruption, though the current color is orange, according to the Alaska Volcano Observatory. No further ash emissions took place after the Sunday explosion. Before Sunday The Alaska Volcano last erupted on 17 May 2017. The eruption occurred at 10:32 pm and continued for almost 73 minutes and spewed ash into the air.

    The Aviation Color Code provides essential information about the Bogoslof Volcano. Now the important fact is this Color Code includes four colors and each color reflects the condition near the volcano. Here the red color indicates the eruption with a significant amount of ash into the air. The orange color says there is almost no emission of ash, though the eruption is under way.

    The U.S. News stated that reports from a pilot revealed the eruption of the Bogoslof Volcano on 17 May that formed a cloud of ash. The eruption sent the ash cloud 35,000 feet into the air. After this, the observatory issued warnings to the pilots. The important fact was the wind actually pushed the ash cloud southwest.

    This Alaska Volcano is a submarine stratovolcano. The eruption of the Bogoslof Volcano has been occurring periodically since the mid-December. The observatory opines that additional explosions with the high-altitude ash could happen at any time.

    See the full article here .

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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” 

    AGU bloc

    AGU
    Eos news bloc

    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)

    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 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.

    5
    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.”

    6
    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.”

    4
    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.”

    9
    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.

    10
    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.”

    See the full article here .

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