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  • richardmitnick 4:48 pm on September 25, 2020 Permalink | Reply
    Tags: , , Eos, , Kīlauea Volcano on the island of Hawaii USA,   

    From Eos: “From Lava to Water: A New Era at Kīlauea” 

    From AGU
    Eos news bloc

    From Eos

    9.25.20
    Patricia A. Nadeau
    Angela K. Diefenbach
    Shaul Hurwitz
    Donald A. Swanson

    1
    U.S. Geological Survey scientists stand at the crater rim at Kīlauea Volcano on 26 October 2019, preparing to use UAS to sample the water lake below. The appearance of this lake after Kīlauea’s 2018 eruption could presage explosive eruptions to come. Credit: Photograph by J. Adams, U.S. Geological Survey.

    On a misty, gray morning, scientists watched with anticipation as a water sampler dunked beneath the surface of a small lake. Once water was retrieved, the researchers made preliminary measurements of pH and conductivity in the field before preparing the remaining sample for the lab.

    Such a scene might be common for hydrologists, ecologists, or water chemists, but this was no ordinary sampling expedition. Last October, it was a first for volcanologists at the U.S. Geological Survey’s (USGS) Hawaiian Volcano Observatory (HVO). The water they collected was not from a typical mountain stream or tropical wetland, but instead from the recently formed and historically unprecedented crater lake at the summit of Kīlauea Volcano. Further, the sample was not obtained by merely walking to the lakeshore and filling a bottle; its retrieval required the use of unoccupied aircraft systems (UAS)—drones in everyday language—operated by a pilot a kilometer away, high above on the crater rim.

    2
    Fig. 1. On 3 May 2018, the lava lake in Kīlauea’s Halema‘uma‘u Crater was approximately 200 meters wide (left). Two years later, Kīlauea’s water lake, shown here on 3 May 2020, is approximately 130 meters wide (right). Lake widths are given for the dimensions from left to right in both photos. Credits: Photographs by C. Parcheta and M. Patrick, U.S. Geological Survey.

    The circumstances were even more remarkable considering that just 18 months earlier, in April 2018, the crater held not a water lake but an active lava lake—the manifestation of a decade-long summit eruption at Kīlauea (Figure 1). What followed from May to September 2018 was one of the largest eruptions, and the most destructive, at Kīlauea since 1790.

    3
    Lava erupts from a fissure in the Leilani Estates neighbourhood near Pahoa on the island of Hawaii, on May 24, 2018 (Grace Simoneau/FEMA via Associated Press)

    The 2018 eruptive sequence drained the lava lake and shallow magma reservoir, feeding fissures along the volcano’s lower East Rift Zone that covered 35 square kilometers with lava [Neal et al., 2019 Science]. That partial evacuation of Kīlauea’s summit magma resulted in a collapsed crater more than 500 meters deeper and 825 million cubic meters larger than it was before the eruption [Anderson et al., 2019 Science], the first water lake in written history at Kīlauea, and a new era of science and monitoring for the Hawaiian Volcano Observatory.

    A New Explosive Period?

    Since the start of the written record of Kīlauea about 200 years ago, the volcano has repeatedly produced lava flows and lava fountains. This style of effusive eruptive activity is what most people, including many geologists, picture when they think of Kīlauea. Such eruptions, although sometimes destructive, are not often life-threatening. What many people may not realize, however, is that Kīlauea has a long history of large, hazardous explosions.

    4
    Fig. 2. These deposits from 18th century explosive eruptions on the rim of Kīlauea caldera are 1 kilometer northwest of the present-day water lake. The scale shows centimeters and inches. Credit: Photograph by D. Swanson, U.S. Geological Survey.

    In fact, a period of predominantly explosive activity lasting some 300 years, including an eruption that killed hundreds of people in 1790 (Figure 2), came to an end in the early 1800s. An even longer explosive period took place between 200 BCE and 1000 CE [Swanson et al., 2014 Geology].

    Why Kīlauea’s eruptive style cycles between effusive and explosive is not entirely understood, but water originating from sources other than magma probably plays a critical role. Textural evidence—such as the dominance of older, recycled rock fragments and the quenched (rapidly cooled) nature of some particles—in Kīlauea’s ash layers indicates that many, perhaps most, explosive eruptions have occurred when groundwater or lake water was vaporized, either by heat given off by the magma (resulting in phreatic eruptions) or by the magma itself (resulting in phreatomagmatic eruptions). Although groundwater alone could have been involved in many explosions, ash from some specific past eruptions suggests that a lake was present at times. That ash contains more dissolved water and sulfur compared with ash that did not interact with lake water and was erupted directly to the atmosphere [Mastin et al., 2004 Journal of Volcanology and Geothermal Research]. Such a lake could have formed after a collapse of the caldera floor and after sufficient cooling of the magma conduit [Hsieh and Ingebritsen, 2019 JGR Solid Earth].

    Now there is water in a collapsed caldera once again. Are we entering a new cycle of explosive, rather than effusive, activity at Kīlauea? Will we see dangerous explosions next? Hazards associated with such explosions, including ballistic ejection of rocks, ashfall, and surges of searing ash and gas, could endanger nearby communities as well as visitors to the popular Hawai‘i Volcanoes National Park.

    Unfortunately, phreatic activity often begins suddenly and is difficult to forecast. The world saw the havoc that such eruptions can wreak in September 2014, when a small phreatic eruption at Japan’s Mount Ontake killed 63 hikers. A December 2019 phreatic eruption at Whakaari (White Island), New Zealand, resulted in 21 fatalities. Many of Kīlauea’s past explosions have been much larger than those recent events at Ontake and Whakaari.

    Determining whether Kīlauea is likely to erupt explosively—and issuing warnings before it does—is a formidable task for HVO scientists and their colleagues.

    Unfamiliar Scientific Territory

    HVO was founded in 1912 by Thomas Jaggar, an American volcanologist whose pursuits involved measuring lava temperature, collecting volcanic gases, and installing seismometers to detect earthquakes. Over the years, HVO improved on his methods and added other monitoring techniques. In the 1960s, scientists started measuring ground tilt, which can indicate inflation and deflation of subsurface magma reservoirs, electronically. They began using sunlight to measure sulfur dioxide (SO2) emissions in the 1970s, and they employed GPS sensors to detect ground motion beginning in the 1990s [Tilling et al., 2014 USGS]. Computational and instrumental advances since then have further revolutionized data collection and analysis.

    All the measurements at Kīlauea in HVO’s 108-year history have been made during the volcano’s modern period dominated by effusive activity. More than 50 explosive eruptions did take place at Kīlauea’s Halema‘uma‘u summit crater in 1924, but none were as large as those in 1790 and earlier. Despite indications of water possibly influencing the 1924 explosions [Jaggar and Finch, 1924 American Journal of Science; Stearns, 1925 Bulletin volcanologique] no lake was present.

    Even without the elevated explosive hazard, the presence of a water lake today warrants adding water sampling to HVO’s repertoire, as water interacts with volcanic gases, particularly SO2. Because magma progressively releases gases during its ascent, increases in SO2 emissions can herald coming volcanic unrest and eruptive activity. However, if those gases dissolve into water rather than escaping to the atmosphere, that geochemical signal could be missed.

    By late 2018, Kīlauea’s SO2 emission rate was the lowest measured since the advent of such monitoring in the 1970s, and those low levels persist today. The low rate could result from magma being too deep to release much sulfur, from reduced magma supply to the summit region, or from SO2 released from shallower magma dissolving into water. Thus, the chemistry of the lake water and its dissolved constituents can provide clues about magma beneath Kīlauea’s summit.

    The association of surface water with enhanced explosive potential only heightens the need to sample and study the water regularly. But the lake is located at the base of a steep, unstable crater, hundreds of meters below the crater rim, which makes sampling on foot impossible and deployment of geophysical and geochemical sensors for continuous monitoring very difficult. Those steep sides, a lack of emergency landing sites, and the potential for dangerous volcanic gases to pool in the crater also make sampling via helicopter inadvisable.

    Yet the need to sample the water remains. So in the tradition of continually pursuing advances in volcano monitoring technology, HVO turned to UAS to draw water from the volcano’s new lake.

    Send in the Drones

    Unoccupied aircraft systems [UAS] have become more common in volcanology in recent years, but prior uses of UAS by the USGS for volcano monitoring had occurred primarily through university partnerships or through the USGS Volcano Disaster Assistance Program‘s work with international colleagues. However, when Kīlauea’s activity began to escalate in 2018, HVO tapped UAS to support monitoring efforts, particularly in areas that were inaccessible or too hazardous for ground crews or traditional aircraft. The ensuing 4-month-long federal government UAS response was the longest and largest of its kind—involving more pilots, flights, and data collection than previous efforts—and it marked the first time the USGS deployed its own UAS fleet in response to a volcanic crisis.

    UAS were used extensively throughout the eruption to provide quick-turnaround data to scientists and on-demand, 24/7 support to emergency managers. Aboard various UAS, including small and large multirotor and fixed-wing aircraft, were gas sensors as well as cameras that provided livestream video to emergency operations centers. Videos taken over the lava channel enabled volcanologists to calculate the rates at which lava was erupting. Photogrammetry surveys provided data for high-resolution digital elevation models (DEMs), which yielded estimates of erupted lava volume, flow advance rates, and flow path forecasts. At Kīlauea’s summit, a time series of DEMs captured the caldera collapse in unprecedented detail.

    After the 2018 eruption, it was clear that the need for UAS at Kīlauea would persist. For years, scientists had made gas measurements at Kīlauea’s summit both on foot and by vehicle traverse. But the road used for these measurements had collapsed into the crater. Gas vents (fumaroles) that HVO sampled to determine gas chemistry were also destroyed by the collapse. Although new fumaroles have since appeared, they are all inaccessible, located on the steep walls of the deepened crater.

    Since 2018, the use of UAS has supplanted the now unfeasible former methods. A specialized sensor package that samples emitted gases to measure concentrations of carbon dioxide (CO2), SO2, hydrogen sulfide, and water can be mounted on UAS. Data collected are then used to assess the spatial distribution of outgassing, to determine the chemistry of fumarolic gases, and to make preliminary assessments of the volcano’s CO2 emission rate, which can provide information about deep magma supply to the volcano.

    Close study of the chemistry and textures of older deposits at Kīlauea is crucial for assessing the volcano’s past, and UAS provide the safest way to begin investigating rocks newly exposed by the crater collapse that have never before been studied [Anderson et al., 2019 Science ]. But as with the fumaroles, many sites of interest are on steep crater walls or even on cliff faces. HVO will use the imaging capabilities of UAS to assess which deposits will be most valuable for study and which might be safely accessible for sampling.

    6
    Fig. 3. A scientist from the Hawaiian Volcano Observatory readies the water sampler, attached to the UAS, for takeoff (top). The UAS (small dark object near center of photo) hovers over the lake surface on 26 October 2019 (bottom). Credits: Photographs by (top) M. Warren and (bottom) C. Parcheta, USGS.

    With UAS becoming a critical tool at HVO, turning to them to sample the new water lake, first spotted in July 2019, was a logical step. Over the past decade, UAS have been used for sampling nonvolcanic water bodies [Lally et al., 2019 Science of The Total Environment]. More recently, volcanic crater lakes have been successfully sampled using UAS, including Kusatsu-Shirane Volcano, Japan [Terada et al., 2018 USGS ], and Whakaari [Kilgour and Scott, 2019 GeoNET NZ].

    However, preparations were not as straightforward as simply devising a sampler and heading into the field. Kīlauea’s summit, and Halema‘uma‘u Crater in particular, is regarded as sacred by Native Hawaiians and other groups, and it is located within Hawai‘i Volcanoes National Park, under the purview of the National Park Service. As part of obtaining formal permission from the National Park Service for UAS water sampling, the park’s Kūpuna consultation group, which includes Native Hawaiian organizations and individuals as well as other interested parties, was asked to identify and address concerns about this work occurring on a sacred landscape. The group was supportive of the scientific objectives of sampling, which allowed HVO to move forward with utilizing UAS as the least invasive and safest tool to accomplish the task.

    On 26 October 2019, HVO scientists obtained the first sample from the growing lake (Figure 3 [above]). A second effort in January 2020 also succeeded in retrieving water samples and temperature data.

    A Watery Window to Activity Below

    Prior to the appearance of the water lake, the only window into the state of groundwater at Kīlauea’s summit was through periodic water level and chemistry monitoring of a research well drilled in the 1970s about 1 kilometer from Halema‘uma‘u Crater. Sulfate (a product of SO2 dissolving in water) and chloride ion concentrations in the well water increased ahead of the 2008 summit lava lake eruption, indicating that groundwater and magmatic gases were interacting [Hurwitz and Anderson, 2019 GRL].

    However, the concentration of sulfate in the water lake is more than 7 times the highest concentrations ever measured in the well. A concentration that high suggests that significant amounts of SO2, which would be emitted into the atmosphere in the absence of water, may instead be dissolving in the lake (and/or the surrounding groundwater), thereby decreasing the SO2 emission rate to the atmosphere. Alternatively, rain percolating through the ground before reaching the lake could be leaching sulfur-rich deposits that accumulated in the summit area before the former lava lake drained.

    Either scenario would affect the chemistry of the new lake, which differs from that of crater lakes at other volcanoes. Hyperacidic volcanic lakes, including those at Poás in Costa Rica, Kawah Ijen in Indonesia, and Whakaari, typically have a pH below 1 (highly acidic), whereas the pH of Kīlauea’s lake is roughly 4 (moderately acidic) and the pH of the well water is about 7 (neutral).

    Laser rangefinder measurements made from the crater rim show that the lake has been deepening by nearly a meter per week since it appeared, although this rate seems to be slowing in recent months. Further sampling missions will be necessary to identify any fluctuations in water chemistry and to determine their causes as the lake continues to grow and change.

    The chance to monitor an incipient volcanic lake is not unprecedented, but it is rare. Kīlauea’s crater lake provides an opportunity to improve the scientific community’s understanding of how such lakes evolve and interact with magmatic systems below.

    Deciphering Kīlauea’s Signals

    It is undoubtedly a new era for Kīlauea Volcano and HVO. Even as we at the observatory use modern tools like UAS, we continue to work to understand the new paradigm of this water lake and an increased potential for explosive eruptions. Given the history of explosive eruptions preserved in the geologic record and in Hawaiian oral tradition, similar lakes may once have been common at Kīlauea; we just have not seen one in modern times.

    Phreatic eruptions are observed at other volcanoes, but we do not yet know the precursors that might presage such an explosion at Kīlauea specifically. Will these precursors be the same as those at other volcanoes or unique to Kīlauea? What signals might we detect in the water chemistry or the seismicity at the volcano that could clue us in on—and allow us to sound alerts about—potential hazards on the horizon?

    Addressing these questions requires that HVO adapt its monitoring and mitigation strategies. At the same time, we must work with local communities, local government, and Hawai‘i Volcanoes National Park to prepare best for whatever happens next at Kīlauea.

    ____________________________________________________
    Acknowledgments

    Sampling of the lake was conducted under research permit HAVO-2019-SCI-0046 from the National Park Service, and we thank Hawai‘i Volcanoes National Park for assistance and support. We also thank colleagues who made the UAS sampling possible, especially Frank Younger, Sara Peek, Tamar Elias, Rich Thurau, Joe Adams, Todd Burton, Tina Neal, and the Department of the Interior’s Office of Aviation Services. Wendy Stovall and Larry Mastin are thanked for reviews that improved this article.
    ____________________________________________________

    References

    Anderson, K. R., et al. (2019), Magma reservoir failure and the onset of caldera collapse at Kīlauea Volcano in 2018, Science, 366(6470), eaaz1822, https://doi.org/10.1126/science.aaz1822.

    Hsieh, P. A., and S. E. Ingebritsen (2019), Groundwater inflow toward a preheated volcanic conduit: Application to the 2018 eruption at Kīlauea Volcano, Hawai‘i, J. Geophys. Res. Solid Earth, 124(2), 1,498–1,506, https://doi.org/10.1029/2018JB017133.

    Hurwitz, S., and K. R. Anderson (2019), Temporal variations in scrubbing of magmatic gases at the summit of Kīlauea Volcano, Hawai‘i, Geophys. Res. Lett., 46(24), 14,469–14,476, https://doi.org/10.1029/2019GL085904.

    Jaggar, T.A., and R. H. Finch (1924), The explosive eruption of Kilauea in Hawaii, 1924, Am. J. Sci., ser. 5, 8(47), 353–374, https://doi.org/10.2475/ajs.s5-8.47.353.

    Kilgour, G., and B. Scott (2019), Sampling the inaccessible: A drone at work on Whakaari/White Island, GeoNet, http://www.geonet.org.nz/news/70PMhjFlyTDOPtwYk0IM2V.

    Lally, H. T., et al. (2019), Can drones be used to conduct water sampling in aquatic environments? A review, Sci. Total Environ., 670, 569–575, https://doi.org/10.1016/j.scitotenv.2019.03.252.

    Mastin, L. G., et al. (2004), What makes hydromagmatic eruptions violent? Some insights from the Keanakāko‘i Ash, Kı̄lauea Volcano, Hawai‘i, J. Volcanol. Geotherm. Res., 137(1), 15–31, https://doi.org/10.1016/j.jvolgeores.2004.05.015.

    Neal, C. A., et al. (2019), The 2018 rift eruption and summit collapse of Kīlauea Volcano, Science, 363(6425), 367–374, https://doi.org/10.1126/science.aav7046.

    Stearns, H. T. (1925), The explosive phase of Kilauea Volcano, Hawaii, in 1924, Bull Volcanol., 2(2), 193–208, https://doi.org/10.1007/BF02719505.

    Swanson, D. A., et al. (2014), Cycles of explosive and effusive eruptions at Kīlauea Volcano, Hawai‘i, Geology, 42(7), 631–634, https://doi.org/10.1130/G35701.1.

    Terada, A., et al. (2018), Water sampling using a drone at Yugama crater lake, Kusatsu-Shirane volcano, Japan, Earth Planets Space, 70(1), 64, https://doi.org/10.1186/s40623-018-0835-3.

    Tilling, R. I., et al. (2014), The Hawaiian Volcano Observatory: A natural laboratory for studying basaltic volcanism, in Characteristics of Hawaiian Volcanoes, U.S. Geol. Surv. Prof. Pap., 1801-1, 1–64, https://doi.org/10.3133/pp18011.

    See the full article here .

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  • richardmitnick 12:49 pm on September 15, 2020 Permalink | Reply
    Tags: "Dams Alter Nutrient Flows to Coasts", , Changing nutrient loads may adversely affect coastal ecosystems., , Eos   

    From Eos: “Dams Alter Nutrient Flows to Coasts” 

    From AGU
    Eos news bloc

    From Eos

    9.15.20
    Elizabeth Thompson

    New models indicate how dams worldwide influence the mix of nutrients in river water reaching the ocean. As more dams are built, changing nutrient loads may adversely affect coastal ecosystems.

    1
    Commercial operation of the Huanza hydroelectric dam near Lima, Peru, began in 2014. Credit: tuproyecto, CC 0.

    The right balance of nutrients is crucial for a healthy coastal ecosystem. If rivers deposit too much nitrogen and phosphorus in coastal areas, algae that flourish on those nutrients can cause dead zones; if too little silicon flows downstream, organisms that depend on it will die off. Human interventions, whether through the addition of nutrients or through direct alteration of river flows, tend to upset natural nutrient balances. In a new study, Maavara et al. [Geophysical Research Letters] modeled how dams affect ratios of nitrogen, phosphorus, and silicon in coastal waters around the world.

    The researchers found that dams withhold algae-fertilizing nutrients at different rates. For example, nitrogen-to-phosphorus ratios in river water reaching the ocean tend to increase because dam reservoirs remove phosphorus more efficiently. However, if human-generated nitrogen emissions are better controlled in coming years, this trend will reverse, and more phosphorus will flow to the coasts instead, according to the team’s models.

    Over time, changes in land use and dam construction may lead to shortages of silicon in discharged water. By 2030, dams could interrupt up to 93% of Earth’s river systems, and most new dams will be hydroelectric dams. Rather than holding back large volumes of water, these dams capture energy as water flows through them. With the long water storage periods of older dams, phosphorus is removed more efficiently than nitrogen or silicon is. However, with shorter flow delays, more silicon is lost, meaning that water reaching the coasts has less silicon relative to nitrogen and phosphorus.

    Marine diatoms, which depend on silicon, are responsible for up to 40% of primary production in oceans. When fewer diatoms occupy coastal regions because of silicon shortages, other algae species take up available nutrients and can cause toxic algal blooms.

    The models predict substantial changes in river-borne nutrient loads in the coming decades, including increasing silicon limitation, in areas where dam building is progressing quickly, such as Southeast Asia, South America, and parts of Africa. But nutrient ratios and how they will change ultimately depend on land use around rivers. The researchers noted that as the effects of dams vary by nutrient and over time, more detailed models are needed to further explore future nutrient relationships along coasts.

    See the full article here .

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    Please help promote STEM in your local schools.

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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 2:17 pm on September 14, 2020 Permalink | Reply
    Tags: "Deconvolving What Lies Beneath the Himalaya", Eos, Thermochronology   

    From Eos: “Deconvolving What Lies Beneath the Himalaya” 

    From AGU
    Eos news bloc

    From Eos

    9.14.20
    Taylor Schildgen
    tschild@uni-potsdam.de

    A new study that combines constraints from the 2015 Gorkha earthquake, forward models of deforming crust, and thermochronology data gives new insights into the structure of the Himalaya.

    1
    Different proposed models of the structure within the Himalaya have different associated thermal fields (colored-coded above). Using thermochronology data, together with forward models of the evolution of these structures through time, it is possible to assess which of these complex pictures most likely captures the true structural complexity of the Himalaya. Credit: Ghoshal et al. [2020], Figure 12.

    The geometry of major faults accommodating deformation in the Himalaya has been the focus of substantial investigative efforts and considerable debate for more than 20 years. The 2015 Gorkha earthquake provided valuable insights into the geometry of the Main Himalayan Thrust, the primary décollement underlying much of the deformed region, but details of the deformation above that structure, the geometry of the décollement farther afield from the rupture zone, and how the deformation has evolved through time have remained poorly constrained.

    Ghoshal et al. Techtonics[2020] address this problem by testing four main hypothesized geometries of deformation with thermokinematic modeling and an extensive set of both new and previously published thermochronology data. This type of data records the cooling history of rocks as they are exhumed to the surface, hence it is well suited to studying crustal deformation.

    This general approach of combining thermochronology data with thermokinematic modeling has been used to investigate crustal deformation with simple geometries in many mountain belts. The novel aspect of this study is that the authors interpret their data in the context of the complex pattern deformation that has been readily observed and mapped in the field, and how the structures have evolved through time.

    While this approach of engaging with realistic levels of complexity limits the number of main hypotheses that can be tested, the authors present a clear picture of what aspects of the overall geometry of deformation can be discerned, what aspects remain unconstrained, and how the results can better inform our understanding of the timing and rates at which individual structures formed.

    See the full article here .

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  • richardmitnick 3:42 pm on September 11, 2020 Permalink | Reply
    Tags: "Cratons Mark the Spot for Mineral Bonanzas", , Cratons are deep extratough regions of the lithosphere., Cratons- where thinning lithosphere made sedimentary basins perfect for metal precipitation., , Eos, , Lithospheric thickness can serve as a treasure map., Sedimentary deposits generally provide the biggest jackpot for mining companies with some finds containing more than 10 megatonnes of metal.   

    From Eos: “Cratons Mark the Spot for Mineral Bonanzas” 

    From AGU
    Eos news bloc

    From Eos

    A new map of the thickness of Earth’s lithosphere contains clues to large deposits of key metals.

    9.11.20
    Bas den Hond

    1
    Productive lead (Pb), zinc (Zn), and copper (Cu) mines line up with the edges of cratons, where thinning lithosphere made sedimentary basins perfect for metal precipitation. Ga = billion years ago; km = kilometers; Mt = megatonnes; CD = clastic dominated; MVT = Mississippi Valley type; sed = sedimentary. Credit: Mark Hoggard.

    The search for deposits of lead, zinc, copper, and nickel might soon become much less of a hit-and-miss activity. Instead of trying their luck over wide areas, mining companies should focus their efforts—and billions of dollars in exploration expenses—on the contours of thick, old pieces of lithosphere strewn across Earth’s continents: cratons.

    Lithospheric thickness can serve as a treasure map, according to Mark Hoggard, an Earth scientist at Harvard University and Columbia University, and his colleagues from the United Kingdom and Australia. They reported their findings in Nature Geoscience.

    Hunting for Giants

    Metals are ingredients of many rocks, but to be exploitable, some process must concentrate them into localized deposits. For lead, zinc, copper, and nickel (collectively known as base metals), such deposits are either magmatic, associated with volcanism, or sedimentary, associated with material collected at the bottom of an inland body of water.

    Sedimentary deposits generally provide the biggest jackpot for mining companies, with some finds containing more than 10 megatonnes of metal. With magmatic deposits, only those of copper seem to be able to reach that size.

    Such giant deposits are sorely needed. “At the moment, due to massive advances in mobile technology and the need to decarbonize the global economy, we are needing more and more metals,” said study coauthor Fred Richards, an Earth and planetary scientist at Harvard University and Imperial College London. In-demand metals include “lead, zinc, copper, and nickel, but also lots of other metals that are accessories to these big deposits, such as cobalt, which goes into car batteries.”

    Considering that about three quarters of the world’s continents are covered by sedimentary basins, knowing to start looking there is of little help in detecting giant deposits. A first hint at how to limit the search space came from northern Australia, where Hoggard and his colleagues noticed that a number of large zinc deposits line up rather neatly along an arc. But it wasn’t clear what geological feature was connected to that shape.

    The group had been working on improved models of how seismic waves travel through Earth’s interior. The results of their work provided a new map of Australia’s lithospheric thickness—and suggested an explanation for that arc of zinc deposits. The line skirted the large craton that makes up the west of the continent.

    2
    Australia provided the first clues to how metal deposits might flock to the edges of cratons. IOCG = iron oxide copper gold ore deposits. Credit: Mark Hoggard.

    Intrigued, the researchers investigated the geography of deposits and cratons in all of Australia, and then worldwide, and found many such juxtapositions. A statistical analysis confirmed that what they saw was not due just to chance.

    Circulating and Scavenging

    But what makes large base metal deposits so likely to snuggle up to cratons? It turns out that such a location provides a whole slew of circumstances that facilitate the process of concentrating metals.

    That process generally starts with an inland sea becoming increasingly salty through evaporation. In the shallowest parts of the sea, the concentration will become so high that salts precipitate to the seafloor. When compressed by subsequent layers of sediment, these precipitates turn into salt rocks, such as gypsum, anhydrite, and halite.

    Seawater then percolates down through the salt rocks and very slowly, with speeds measured in meters per year, travels through faults into deeper rocks. If the heavy, briny fluid passes through oxidized rocks, it becomes oxidized itself, and as a result, it is easy for metals in the rocks to dissolve into the brine and be swept up with it. The resulting metal-rich fluid has been observed, for instance, below the Salton Sea in California.

    As the brine descends, it comes closer to the hot underside of the lithosphere and heats up and expands. This makes it less dense and thus more buoyant, to such an extent that it rises up again, until it cools—just enough to start to sink again. The brine may keep circulating in this way through sedimentary layers for long periods (there is some debate whether those periods are millions of years at a stretch or come in shorter bursts), scavenging metals as it flows.

    But sometimes brine passes through an environment that is reducing, meaning it counteracts the oxidized state of the fluid. In this case, metal finds it harder to stay dissolved in the brine, and some of it will precipitate out. Black shales, for instance, composed of mud sediments laid down in deeper portions of the inland sea, provide just such conditions, and build up metal deposits in their interstices.

    Digging Deeper

    Cratons are deep, extratough regions of the lithosphere. They don’t typically lend themselves to thinning or rifting. But that very resistance makes their edges likely places for thinning of the weaker surrounding lithosphere, and thus perfect for forming sedimentary basins.

    Such basins might even get stacked atop each other, as the lithosphere cycles through stretching and compressing phases. Weakened by the previous events, the edge will give way again and again, possibly allowing metal deposit formation.

    The lithosphere at a craton’s edge is still thicker than elsewhere on a continent, so stretching and thinning it take longer. The slowness of the process gives the brine more time to circulate, and the remaining thickness of the stretched craton’s edge gives it a longer way to go down before temperatures get too high for the metal precipitation processes to work. These circumstances increase the volume of the deposit.

    The research documenting deposits on the craton’s edge clearly has practical implications. According to Hoggard, “our maps work everywhere, including in continents where a geologist’s boot rarely hits the ground—for instance, in parts of Africa and Antarctica—and we can provide an actual probability that a deposit exists, which is what companies need to make financial decisions.”

    And according to the scientists, the research also provides evidence for the stability and longevity of cratons. For instance, some sedimentary metal deposits in North America have been dated to 0.5–1.5 billion years old. For at least that long—apparently while continents broke up, collided, and joined up again—the craton against whose edge these deposits were nestling stayed in one piece.

    It’s good research, according to Jon Hronsky of the mineral exploration consultancy Western Mining Services, which has offices in the United States and Australia. “However, it is a little bemusing to us in the mineral exploration geoscience community that this is the first time these sort of ideas are finally gaining some attention from the general geoscience community,” he told Eos in an email.

    According to Hronsky, “the idea that deep-seated cryptic patterns of weaknesses and discontinuities in the lithosphere control the location of major ore deposits is quite an old one,” and “concepts, relating lithospheric architecture to the location of major mineral deposits, have been fairly central to mineral exploration targeting, at least within the more progressive companies, for about two decades.”

    Hoggard agrees with that as far as magmatic deposits are concerned. But according to him, such relationships so far had not been established for sedimentary deposits. “The data sets we use to image lithospheric structure have only really become available within the last 10 years. Even if someone had an inkling of the relationship before now, they wouldn’t have been able to test it like we can today.”

    See the full article here .

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  • richardmitnick 3:47 pm on September 1, 2020 Permalink | Reply
    Tags: "Severe Cyclones May Have Played a Role in the Maya Collapse", AMO-Atlantic Multidecadal Oscillation, ENSO-El Niño–Southern Oscillation, Eos, Goethe-Universität Frankfurt am Main, One source for finding undisturbed sediments is blue holes- marine sinkholes into which sediments are continually deposited., , , Sediment cores from blue holes like those on Great Abaco Island and Thatch Point (both in the Bahamas) have already provided records of hurricanes in the Caribbean going back about 1500 years., The researchers recovered and studied an 8.5-meter-long sediment core from the Great Blue Hole on Lighthouse Reef off the coast of Belize., The shift happened right around the time when the Maya civilization was in decline., The stress of dealing with the highly variable and intense storms in addition to battling drought may have pushed the Maya over the edge., The tropical cyclone activity of the southwestern Caribbean generally shifted from a less active (100–900 CE) to a more active state (900 CE to modern)., Why the once great Maya civilization withered away is still a matter of debate among historians; archaeologists; and geoscientists.   

    From Goethe-Universität Frankfurt am Main via Eos: “Severe Cyclones May Have Played a Role in the Maya Collapse” 

    1

    From Goethe-Universität Frankfurt am Main

    via

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    Eos news bloc

    Eos

    9.1.20
    Lakshmi Supriya

    Sediment cores from the Great Blue Hole reveal that a series of extreme storms hit the region after 900. The storms may have irreparably damaged an already stressed Maya population.

    1
    Sediments recovered from the Great Blue Hole, off the coast of Belize, hint at extremely severe storms during the late Classic period in Maya history. Credit: iStock/Mlenny.

    Why the once great Maya civilization withered away is still a matter of debate among historians, archaeologists, and geoscientists. The leading theory is that the Maya suffered a series of severe droughts around 800–1100. New evidence suggests there may have been another reason: severe tropical storms.

    Researchers studying past climate records in the Caribbean found that storm activity was weak and predictable up to about 900. At that point, storms became more intense and unpredictable. The stress of dealing with the highly variable and intense storms, in addition to battling drought, may have pushed the Maya over the edge, according to research published in Scientific Reports in July.

    Reconstructing Past Climate

    Atlantic hurricane activity, which includes the Caribbean, and how it varies over the long term are often attributed to the behavior of ocean and atmospheric systems like the Atlantic Multidecadal Oscillation (AMO) and the El Niño–Southern Oscillation (ENSO). “But without long-term observations of storm behavior, it’s hard to speak to these relationships conclusively,” said Richard Sullivan, who studies paleoclimatology at Texas A&M University at Galveston and was not part of the new study.

    2
    Deposits line the 8.5-meter-long sediment core recovered by researchers from the Great Blue Hole off Belize. Credit: Dominik Schmitt.

    Historical or instrumental records of hurricanes and tropical storms go back only a little more than a century. To peer further back in time, scientists often decipher telltale signatures left in sand and mud deposited by ancient storms.

    One source for finding undisturbed sediments is blue holes, marine sinkholes into which sediments are continually deposited. Generally, the sediments in deposition layers are smooth. But when a large storm passes by, it rakes up and deposits coarse particles. Because of the structure of a blue hole, material can be deposited but cannot get out, allowing the feature to act as a near-perfect record of ancient storms.

    Sediment cores from blue holes like those on Great Abaco Island and Thatch Point (both in the Bahamas) have already provided records of hurricanes in the Caribbean going back about 1,500 years.

    Now Dominik Schmitt of Goethe University in Frankfurt, Germany, and colleagues have reconstructed past storms in the region going back 2,000 years. The researchers recovered and studied an 8.5-meter-long sediment core from the Great Blue Hole on Lighthouse Reef off the coast of Belize.

    Upon analyzing the results, Schmitt’s team found evidence of the AMO going back to 300. According to Schmitt, this provides statistical proof that the AMO, along with ENSO, modulates hurricane activity in the southwestern Caribbean.

    When the Weather Changed

    The sediments also revealed something else. “The tropical cyclone activity of the southwestern Caribbean generally shifted from a less active (100–900 CE) to a more active state (900 CE to modern),” said Schmitt. The shift happened right around the time when the Maya civilization was in decline.

    The Classic Maya civilization, which once occupied most of the Yucatán Peninsula, began to wane starting in the late 800s. During the next century, great Maya cities like Copán (in what is now Honduras) and Tikal (in what is now Guatemala) were abandoned.

    Climate change is thought to have been a primary driver of this collapse. The leading theory suggests that a series of severe and prolonged droughts plagued the Yucatán Peninsula, which may have reduced the availability of fresh water and decreased agricultural productivity.

    In addition to drought, the Maya may have had to contend with increased and more unpredictable Caribbean cyclones. The Great Blue Hole sediment core showed five exceptionally thick layers—15 to 30 centimeters—deposited between 700 and 1150. These layers suggest extremely intense cyclones; for comparison, the deposition layer left by Hurricane Hattie, a Category 5 hurricane that passed over the same area in 1961, was just 4 centimeters thick.

    Two of the ancient cyclones struck during drought periods, and the others struck just before and after severe droughts. It’s likely these cyclone landfalls destroyed Maya infrastructure, caused coastal flooding and crop failures, and added to the environmental stress of the intensive drought phases.

    The increased storm activity around 900 is similar to what Sullivan found in his study of sediment cores from a sinkhole south of Tulum, Mexico, near the Maya site of Muyil. Still, he is cautious in interpreting the results, saying they do not necessarily mean that an increase in storm frequency definitely contributed to the Classic Maya collapse.

    However, “it’s not hard to imagine that a culture contending with severe drought and already in decline would have been stressed further by persistent, devastating storms,” Sullivan added. “It is certainly possible that increasing hurricane frequency factored into the collapse of the Mayan empire, but the extent of that contribution is something we may never know conclusively.”

    See the full article here.

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  • richardmitnick 1:50 pm on September 1, 2020 Permalink | Reply
    Tags: "The Underwater Behavior of Oil and Gas Jets and Plumes", Eos, In deep seawater where there are conditions of high pressure and low temperature the release of hydrocarbon compounds can form natural gas hydrates., Natural seeps on the continental margins release hydrocarbons in the form of liquid oil and natural gas., , The multiscale interaction between underwater oil and gas plumes and the environment impacts plume composition and trajectory.   

    From New Jersey Institute of Technology via Eos: “The Underwater Behavior of Oil and Gas Jets and Plumes” 

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    From New Jersey Institute of Technology

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    Eos

    Exploring how the multiscale interaction between underwater oil and gas plumes and the environment impacts plume composition and trajectory.

    1
    Hydrocarbon plumes released to the environment manifest spontaneous changes through the formation of oil droplets and gas bubbles and the release of soluble compounds in the water column. This tank experiment is observing a flow of diesel oil blended with fluorescein dye escaping from a one-inch (2.5 centimeter) pipe at the flow of 500 liters per minute. Major advances have been made for understanding the oil/gas chemistry and physics at depth and the behavior of multiphase plumes (oil, gas, and water). Credit: study conducted by New Jersey Institute of Technology and collaborators at the Department of Interior Ohmsett facility in New Jersey.

    9.1.20

    Michel C. Boufadel
    Scott A. Socolofsky

    Natural seeps on the continental margins release hydrocarbons in the form of liquid oil and natural gas. Hydrocarbons may also be leaked from sunken vessels and damaged pipelines. The most dramatic example of an anthropogenic hydrocarbon release in recent history is the Deepwater Horizon oil well blowout in the Northern Gulf of Mexico in 2010. A recent article in Reviews of Geophysics explores how hydrocarbon liquids and gases behave after being released underwater. Here, two of the authors give an overview of how oil droplets and gas bubbles move around in aquatic environments.

    How do the characteristics of hydrocarbon liquids and gases change after contact with water?

    The majority of chemical compounds in oil and gas do not dissolve in water so, once in contact with seawater they do not mix but rather break up into droplets and bubbles.

    2
    Sequence of photos showing crude oil during release from a 1.0-centimeter pipe to evaluate the oil droplet size distribution. Credit: Study conducted by New Jersey Institute of Technology and collaborators at the Department of Interior Ohmsett facility in New Jersey.

    The sizes of droplets and bubbles depends on the balance between the destructive force of mixing energy in various compartments of the environment, particularly the release point (vent, pipe, etc..) and the resistive force mainly due to the interfacial tension between the oil and water or gas and water (the interfacial tension force is the physical factor behind the statement “oil and water do no mix”).

    3
    The flow of gas impacts the plume and the size of the oil droplets (a) In oil-only releases, ligaments form at the interface of oil and water and they get entrained into plume and subsequently disintegrate due to turbulence within the plume. An intact core of oil exists within a few diameters of the orifice, (b) For oil and gas release, oil droplets form also in the center of the jet, especially if the flow is “churn” (where oil and gas tumble within the conduit). Credit: Boufadel et al. [2020], Figure 6.

    In deep seawater, where there are conditions of high pressure and low temperature, the release of hydrocarbon compounds can form natural gas hydrates. These are solid deposits with an ice-like crystalline structure that changes the solubility and bioavailability of the hydrated compounds.

    How do they behave as they rise through the water column?

    A large volume of hydrocarbon forms an underwater plume. As the plume rises, it entrains water in it, and eventually each individual oil droplet and gas bubble continues rising at its “terminal” velocity, which results from a balance between its buoyancy and its drag.

    During ascent, small droplets (less than 300 microns) drift with the currents, while larger ones tend to rise vertically to the surface. Droplets and bubbles lose mass as they rise due to dissolution in water.

    How far and fast can they travel in the aquatic environment?

    Gas bubbles typically rise at velocities between 10 and 30 centimeters per second, with greater speeds associated with large bubbles. Large (millimeter-scale) oil droplets rise at similar speeds of up to 20 centimeters per second; smaller oil droplets can rise very slowly while micro-scale oil droplets have hardly move upwards at all.

    The lateral transport of oil droplets and gas bubbles depend on two main factors: currents and the rise time from depth. Gas bubbles surface in minutes to hours, limiting the lateral drift to a scale of kilometers. Large oil droplets have similar rise times and lateral movements. In contrast, small oil droplets can remain sequestered in the ocean water column for long periods and be transported tens to hundreds of kilometers from the release point.

    In the case of an oil-well blowout, the collective buoyancy of the oil and gas can form a plume, which may rise at up to 1 meter per second, carrying a whole collection of gas bubbles and oil droplets collectively upward from the source. In the case of the Deepwater Horizon, the plume of oil and gas was trapped by the ocean density stratification. This created a lateral intrusion of dissolved gas, light hydrocarbons, and very small oil droplets. Larger oil droplets rose out of the intrusion layer and surfaced largely within kilometers of the blowout footprint on the water surface.

    What have been some recent advances in our understanding?

    There has been tremendous improvement in models to describe oil droplet and gas bubble formation especially at depth, as well as observations in the laboratory at the submillimeter scale to validate them. There have also been advances in “fate models” to understand the real-fluid chemistry and thermodynamics of oil and gas in the ocean water column.

    Meanwhile, new computational fluid dynamics (CFD) models for jet and plume dynamics of oil and gas in seawater have seen transformative advances.

    What are some of the unresolved questions where additional research, data or modeling is needed?

    Despite numerous laboratory and field observations of oil and gas behavior in seawater, we still lack observations of complete oil droplet size distribution or complete gas bubble size distribution from large orifices (10 centimeters or larger) under highly turbulent conditions. This is further complicated by the behavior of gas under high pressure (gas density is 1 kilogram per cubic meter at the water surface but could reach 150 kilograms per cubic meter at depth).

    As of yet, computational fluid dynamic models are unable to capture the droplet or bubble fragmentation process, which is the result of forces in various fluids interacting at the micron scale (with different equations for different fluids). In addition, the effectiveness of added dispersants is not fully quantified in the presence of three phases: water, oil, and gas.

    See the full article here .

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    NJIT offers 125 undergraduate and graduate degree programs in six specialized schools instructed by expert faculty, 98 percent of whom hold the highest degree in their field.

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  • richardmitnick 9:39 am on July 28, 2020 Permalink | Reply
    Tags: "The Rise of Machine Learning", , Eos   

    From Eos: “The Rise of Machine Learning” 

    From AGU
    Eos news bloc

    From Eos

    7.28.20
    Heather Goss

    1
    Credit: iStock.com/GarryKillian

    Our August issue explores the way we process, analyze, and clearly present the massive amounts of information collected by scientists today.

    2

    We cover the data problem here in Eos quite a bit. But “the data problem” is a misnomer: With so many ways to collect so much data, the modern era of science is faced not with one problem, but several. Where we’ll store all the data is only the first of them. Then, what do we do with it all? With more information than an army of humans could possibly sift through on any single research project, scientists are turning to machines to do it for them.

    “I first encountered neural networks in the 1980s,” said Kirk Martinez, Eos science adviser for AGU’s informatics section and a professor at the University of Southampton, United Kingdom, when he suggested the theme for our August issue. “Neural networks were a ‘biologically inspired’ way to make algorithms which could be trained to respond to certain inputs. Since then it has blossomed into a part of machine learning as we know it today.”

    Grappling with climate change research is one of the clearest places where machine learning will be crucial. “Currently, less than 5% of available environmental observational data are used in numerical models of Earth systems,” writes Amy McGovern and colleagues in “Weathering Environmental Change Through Advances in AI.” Recent innovations for artificial intelligence methods will allow researchers to harness more of those data, but realizing the full potential will require interdisciplinary collaboration to build the proper infrastructure.

    What then? Residents in the U.S. Great Plains are already getting AI weather forecasts that give 36 hours of notice before a hailstorm, write McGovern et al. AI is mapping ecological provinces in the ocean, and soon it could even decode alien atmospheres, if scientists can overcome “the curse of dimensionality.”

    Machine learning, said Martinez, is going to be an essential part of data analysis in Earth and space sciences. “It gives us a way to classify images and signals that we would have struggled to process before,” but we also need to understand its limitations.

    The discoveries machine learning can help scientists make come at a cost. The processing power required for these algorithms requires massive amounts of energy—and many in the geoscience community are clamoring for even more powerful supercomputers. In Earth System Modeling Must Become More Energy Efficient, Richard Loft writes about the irony of creating a significant carbon footprint to build climate models that tell us what burning all that carbon is doing to climate. Instead, he urges scientists to lead by example, offering several ways to think about—and lower—the energy requirements of these systems.

    On the theme of analyzing and interpreting data, don’t miss Stephanie Zeller and David Rogers’s Visualizing Science: How Color Determines What We See. They write, “Visualization’s single most effective encoder—color—remains vastly understudied,” but here they offers a masterful introduction of the many considerations involved when conveying data. Needless to say, the images illustrating their article are page turners.

    We hope you enjoy this issue on data and machine learning and that it makes you think about the ways in which you might use it—or improve its use—in your own work.

    See the full article here .

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  • richardmitnick 11:42 am on June 19, 2020 Permalink | Reply
    Tags: "Modeling Fluid Migration in Subduction Zones", , Eos, ,   

    From Eos: “Modeling Fluid Migration in Subduction Zones” 

    From AGU
    Eos news bloc

    From Eos

    16 June 2020
    Ikuko Wada
    iwada@umn.edu

    Leif Karlstrom

    1
    The Franciscan complex on Santa Catalina Island in California exemplifies the role of fluids in subduction zone processes. In this outcrop, pale beige silicic magmatic dikes crosscut white quartz veins, likely reflecting distinct episodes of hydraulic fracturing of the crust by overpressurized fluids. Image width is about 12 meters. Credit: John Paul Platt

    Some of the biggest challenges in understanding subduction zone processes and their associated hazards arise from the wide range of spatial and temporal scales of the underlying phenomena. Even if we look at the same question—say, how fluid migration affects megathrust faults or volcanic systems—various types of data and models available at different scales often lead to conclusions that are equally relevant but difficult to synthesize or validate.

    To further research efforts on these issues, especially on subduction-related geohazards, a new community initiative called SZ4D has been developed. SZ4D expands upon international research in subduction zone science supported by the National Science Foundation (NSF) Geodynamic Processes at Rifting and Subducting Margins (GeoPRISMS) program, which is in its final stage. Allying with SZ4D, the NSF-funded Modeling Collaboratory for Subduction Research Coordination Network (MCS RCN) organized three workshops focused on identifying research approaches that could lead to more unified subduction science, particularly between volcanic and earthquake processes that historically have been studied independently. The hope is that these activities together will set off a wave of broad rethinking about the future directions of subduction zone science, with an integrated collaboratory to accelerate modeling efforts across disciplines.

    Three Workshops

    The first MCS RCN workshop was held at the University of Minnesota in May 2019 to address fluid migration as a basis for common future research directions across subduction science. With 56 in-person and 90 online participants, we obtained input from a range of Earth scientists, including modelers and observationalists at all career stages.

    The second MCS RCN workshop, on modeling megathrust systems, was held at the University of Oregon in October 2019. And the third workshop, on modeling the subsurface aspects of volcanic systems, was scheduled for summer 2020, but its timing is now unknown.

    The topic of the first workshop—migration of fluids (both aqueous and silicate melts)—is widely recognized as an integral component across subduction zone processes, including megathrust earthquakes like the 2011 Tohoku-Oki earthquake in Japan and volcanic eruptions like the 2019 eruption of Whakaari (White Island) in New Zealand, both of which caused the unanticipated loss of human lives and highlighted gaps in our understanding.

    Current research on the dynamics of multiphase, multicomponent fluid systems is fragmented across many subdisciplines; thus, there are significant opportunities for synergy. Here we build on the outcome of the first workshop by highlighting opportunities and challenges in integrating models across spatial and temporal scales in subduction zones.

    The Challenge of Scale

    Most fluid migration studies focus on subdomains of subduction zones, such as the seismogenic part of the megathrust system, the ductile part of the mantle wedge, and the crustal magma transport system, as defined by the spatial or temporal scales of the processes being studied. This partitioning is artificial from a system-scale standpoint because these subdomains do not operate independently, but it is highly practical given that observations are often limited to restricted scales and the relation between subdomains is difficult to resolve.

    2
    Diagram illustrating key components of a subduction system and models of fluid transport processes for selected subdomains, highlighting different modeling approaches. (a) A dynamic earthquake rupture model showing pore pressure change across a fault (modified from Heimisson et al. [2019]). (b) A tens-of-kilometers-scale model of fluid flow and deformation in a megathrust system (modified from Menant et al. [2019]). (c) A micromechanical model of volume-decreasing dehydration (left) and volume-increasing hydration (right) reactions at mineral grain scale (modified from Okamoto and Shimizu [2015]). (d) A model for fluid circulation in the deforming mantle wedge with varying mineral grain size (magenta contours) and viscosity (yellow contours; modified from Cerpa et al. [2017]). (e) An integrated model for magma ascent from mantle through the lithosphere, showing a vertical strength profile (left), melt fraction (top right), and deviatoric strain rate (bottom right; modified from Keller et al. [2013]). (f) A model for a recharge event into a crystal-rich magma reservoir (modified from Bergantz et al. [2015]). (g) An analogue model for dike-to-sill emplacement in an elastic crust (modified from Kavanagh et al. [2018]). (h) Lumped parameter model for the 2004 Mount St. Helens volcanic eruption from a magma chamber through a volcanic conduit to a surface lava dome (modified from Anderson and Segall [2013]).

    Mathematical models are often developed for a particular set of processes and subdomains with simplifying assumptions that are appropriate for the chosen scale but that may not be appropriate at other scales or in other subdomains. Such simplifications involve relegating unmodeled physical processes to initial and boundary conditions, parameterizing unmodeled processes, or simply ignoring them.

    For example, larger-scale models of megathrust dynamics and arc magmatism must parameterize processes, such as multiphase reactive transport kinetics and fracture mechanics, that occur at smaller scales below the resolution of the numerical simulations. Smaller-scale models often face a similar problem in that they depend on larger-scale estimates of background stress, thermal states, or fluid flux that are not calculated within the smaller models and therefore must be specified on an ad hoc basis. Smaller-scale models might be viewed as elements that eventually fit into integrative models to provide larger-scale predictions, and indeed, one possible realization of the MCS RCN is to produce such a LEGO brick modeling framework.

    Coupling Models and Achieving Consistency

    Meaningfully coupling models is not trivial. Smaller-scale models focused on particular fluid processes in subduction zones are often subject to highly variable observational constraints or even to a lack of observational data. Larger integrative models face challenges involving the computational cost of incorporating processes on all relevant scales, requiring numerical approaches that push the limits of scientific computing.

    One of the key challenges is how to properly couple processes that occur at different spatial and temporal scales. For example, how should the mechanics of slow slip modeled at the meter scale be incorporated in the deformation of the megathrust system that is modeled at a 100-kilometer scale and vice versa? How should elasticity and the brittle behavior of the crust around magma reservoirs and dikes be represented in lithospheric-scale magma migration models? Do unsteady and nonequilibrium effects arising from reactive transport in deformable two-phase media control fluid transport in the mantle wedge? Without the knowledge of how different phenomena influence each other, their overall effects are difficult to quantify.

    Coupling models across different scales or subdomains in a consistent manner requires that we quantify fluid mass flux between domains, but this remains a significant challenge. For example, to predict magma flux into the lithosphere and subsequent volcanism at a narrow arc front or back-arc environment, we must know the permeability structure and melt ascent rates at the lithosphere-asthenosphere boundary. This in turn depends on the production and spatial focusing of melts within the mantle wedge below the boundary, which likely depend on fluid flux from the downgoing slab as well as on the evolving geometry of the lithosphere-asthenosphere boundary. Similarly, in quantifying the buildup of pore fluid pressure and the formation of hydrous phases in the megathrust system, we must know how much of the deep slab-derived fluid migrates within the downgoing material and along the plate interface.

    Analogous issues arise in Earth surface landscape and critical zone evolution models that couple megathrust and volcanic activity to long-term climate. Such problems require an integrated system-scale approach that can resolve evolving plate geometry over millions of years with meters-per-year (or greater) ascent velocities of fluids. Models focused on particular processes (often at a smaller scale) play a crucial role in this development, but identifying the underlying physics and parameter sensitivity must be resolved using integrated models.

    Commonalities in Fluid Migration Problems

    Not all subduction zone subdomains exhibit the same degree of constraints or community consensus regarding validation—challenges that are illustrated by the variability of timing of earthquakes and volcanic eruptions. Both earthquakes and volcanic eruptions occur episodically in response to quasi-steady tectonic forcing (either plate loading or mantle melting) over long timescales. This forcing generates patterns of stress and fluid migration that affect the events’ occurrence and magnitude.

    In volcanology, predictions of crustal magma storage and transport mechanisms that control the eruption cycle depend on poorly understood physical processes. Developing long-term eruption cycle models is thus difficult because of incomplete sampling of the full eruption magnitude-frequency distribution as well as of uncertainties in how to link to long-term constraints from the plutonic record with active volcanism. Earthquake cycle models are more mature in comparison.

    When meaningful commonalities are found, opportunities arise for advancing both earthquake science and volcanology. For example, eruption cycle models might benefit from numerical approaches developed in modeling the multiscale deformation and fluid processes at play in the megathrust system. Likewise, earthquake cycle models could benefit from the multidisciplinary approach that volcanologists have developed to integrate multiscale constraints on fluid transport and storage. Identifying common ground for knowledge sharing and model development is a challenge that determines the practicality of system-scale models.

    Observational Constraints

    To better understand eruption and earthquake cycles or virtually any other grand challenge in subduction zone science, models must grapple with large variability in the degree of observational completeness. For example, one to three approximately magnitude 9 earthquakes occur every 100 years globally [McCaffrey, 2008], but among different faults, recurrence rates are more variable. Global recurrence intervals for the largest subduction-related volcanic eruptions (approximately magnitude 8 or greater based on erupted mass [Pyle, 2015]) are orders of magnitude larger [Rougier et al., 2018] and even more poorly constrained because of sparse records.

    The distributions of smaller events that define earthquake and eruption cycles in terms of magnitude-frequency relationships are also distinct. Along instrumented megathrust faults, earthquakes as small as about magnitude zero can be recorded in some regions (e.g., Nankai, Japan [Nanjo and Yoshida, 2018]). Earthquake cycles also include a spectrum of slow-slip and aseismic-slip events that occur along the megathrust fault systems.

    For arc volcanoes, a similar catalog of recent (Holocene) eruptions is considered complete down to a magnitude of perhaps 4 [Sheldrake and Carrichi, 2017], despite more frequent smaller events globally. This degree of completeness of the volcanic record reflects much poorer recording and preservation of eruptions relative to earthquakes. To complicate matters, pathways of magma ascent often migrate on timescales similar to eruption recurrence intervals. Thus, models for eruption cycles must account for both changing pathways and timescales of magma ascent, whereas megathrust earthquake cycles generally occur on known faults. Such differences in observational constraints represent an outstanding challenge for cross-disciplinary integration of earthquake and volcano science, requiring coordinated community efforts.

    A Modeling Collaboratory

    One vision of the MCS RCN is to identify and use integral components, such as the role of fluids, to unify subduction zone science. At the first workshop, participants agreed that there is a great need to address knowledge gaps among scientists working in different subduction zone subdomains. The MCS RCN’s long-term goal of building a framework of modeling and data analysis tools for subduction zone processes also requires resolving technical disconnects. We can envision a modeling collaboratory to provide a research environment in the form of workshops, training, and community forums to address both of those needs.

    Building community modeling resources, such as approaches for model validation, uncertainty quantification, and benchmarking exercises, is important in disseminating research efforts effectively. The modeling collaboratory could serve as a platform for such activity, but maintaining cross-disciplinary research efforts will require that common objectives among different disciplines be clearly defined. The fluids workshop represented one organizational step toward this goal.

    The full workshop report describes subduction zone–wide research foci from a fluids perspective and possible realizations for future collaborative efforts. A report from the second workshop is forthcoming.

    [Please visit the full article for links to references cited.]

    Acknowledgments

    This article is built on the outcome of the first MCS RCN workshop, held at the University of Minnesota in May 2019, and we thank the workshop participants for their contribution. Special thanks are owed to the writing committee of the workshop report on which this article is partially based: D. Arcay, L. Caricchi, P. Fulton, T. Gerya, K. Iacovino, T. Keller, R. Lauer, G. Lotto, L. Montesi, T. Sun, H. Vrijmoed, and J. Warren. We also thank K. Anderson, G. Bergantz, N. Cerpa, E. Heimisson, J. Kavanagh, T. Keller, A. Menant, and A. Okamoto for providing the plots included in the figure. This article benefited from insightful comments from the MCS RCN Steering Committee and the Writing Committee. L.K. acknowledges support from NSF grant 1848554.

    References

    Anderson, K., and P. Segall (2013), Bayesian inversion of data from effusive volcanic eruptions using physics‐based models: Application to Mount St. Helens 2004–2008, J. Geophys. Res. Solid Earth, 118(5), 2,017–2,037, https://doi.org/10.1002/jgrb.50169.

    Bergantz, G. W., J. M. Schleicher, and A. Burgisser (2015), Open-system dynamics and mixing in magma mushes, Nat. Geosci., 8(10), 793–796, https://doi.org/10.1038/ngeo2534.

    Cerpa, N. G., I. Wada, and C. R. Wilson (2017), Fluid migration in the mantle wedge: Influence of mineral grain size and mantle compaction, J. Geophys. Res. Solid Earth, 122(8), 6,247–6,268, https://doi.org/10.1002/2017JB014046.

    Heimisson, E. R., E. M. Dunham, and M. Almquist (2019), Poroelastic effects destabilize mildly rate-strengthening friction to generate stable slow slip pulses, J. Mech. Phys. Solids, 130, 262–279, https://doi.org/10.1016/j.jmps.2019.06.007.

    Kavanagh, J. L., et al. (2018), Challenging dyke ascent models using novel laboratory experiments: Implications for reinterpreting evidence of magma ascent and volcanism, J. Volcanol. Geotherm. Res., 354, 87–101, https://doi.org/10.1016/j.jvolgeores.2018.01.002.

    Keller, T., D. A. May, and B. J. P. Kaus (2013), Numerical modelling of magma dynamics coupled to tectonic deformation of lithosphere and crust, Geophys. J. Int., 195(3), 1,406–1,442, https://doi.org/10.1093/gji/ggt306.

    McCaffrey, R. (2008), Global frequency of magnitude 9 earthquakes, Geology, 36(3), 263–266, https://doi.org/10.1130/G24402A.1.

    Menant, A., S. Angiboust, and T. Gerya (2019), Stress-driven fluid flow controls long-term megathrust strength and deep accretionary dynamics, Sci. Rep., 9, 9714, https://doi.org/10.1038/s41598-019-46191-y.

    Nanjo, K. Z., and A. Yoshida (2018), A b map implying the first eastern rupture of the Nankai Trough earthquakes, Nat. Commun., 9, 1117, https://doi.org/10.1038/s41467-018-03514-3.

    Okamoto, A., and H. Shimizu (2015), Contrasting fracture patterns induced by volume-increasing and -decreasing reactions: Implications for the progress of metamorphic reactions, Earth Planet. Sci. Lett., 417, 9–18, https://doi.org/10.1016/j.epsl.2015.02.015.

    Pyle, D. (2015), Sizes of volcanic eruptions, in The Encyclopedia of Volcanoes, 2nd ed., edited by H. Sigurdsson et al., chap. 13, pp. 257–264, Academic, Waltham, Mass., https://doi.org/10.1016/B978-0-12-385938-9.00013-4.

    Rougier, J., et al. (2018), The global magnitude–frequency relationship for large explosive volcanic eruptions, Earth Planet. Sci. Lett., 482, 621–629, https://doi.org/10.1016/j.epsl.2017.11.015.

    Sheldrake, T., and L. Caricchi (2017), Regional variability in the frequency and magnitude of large explosive volcanic eruptions, Geology, 45(2), 111–114, https://doi.org/10.1130/G38372.1.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

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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 9:27 am on May 22, 2020 Permalink | Reply
    Tags: "A Plate Boundary Emerges Between India and Australia", , Eos, Mid-ocean ridges reveal plate boundaries., Multibeam bathymetry, , Slip rates, Tectonic plates blanket the Earth like a patchwork quilt.   

    From Eos: “A Plate Boundary Emerges Between India and Australia” 

    From AGU
    Eos news bloc

    From Eos

    18 May 2020
    Katherine Kornei

    1
    Mid-ocean ridges, like this one near Vancouver Island, Canada, reveal plate boundaries. Credit: Ocean Networks Canada.

    Tectonic plates blanket the Earth like a patchwork quilt.

    The tectonic plates of the world were mapped in 1996, USGS.

    Now, researchers think they’ve found a new plate boundary—a line of stitching in that tectonic quilt—in the northern Indian Ocean. This discovery, made using bathymetric and seismic data, supports the hypothesis that the India-Australia-Capricorn plate is breaking apart, the team suggests.

    Earthquakes in Unexpected Places

    In 2012, two enormous earthquakes occurred near Indonesia. But these massive temblors—magnitudes 8.6 and 8.2—weren’t associated with the region’s notorious Andaman-Sumatra subduction zone. Instead, they struck within the India-Australia-Capricorn plate, which made them unusual because most earthquakes occur at plate boundaries.

    These earthquakes “reactivated the debate” about the India-Australia-Capricorn plate, said Aurélie Coudurier-Curveur, a geoscientist at the Institute of Earth Physics of Paris.

    Some scientists have proposed that this plate, which underlies most of the Indian Ocean, is breaking apart. That’s not a wholly unexpected phenomenon because this plate is being tugged in multiple directions, said Coudurier-Curveur. Its eastern extent is sliding under the Sunda plate, but its northern portion is buckling up against the Himalayas, which are acting like a backstop.

    “There’s a velocity difference that is potentially increasing,” said Coudurier-Curveur, who completed this work while at the Earth Observatory of Singapore at Nanyang Technological University.

    Zooming in on Fractures

    Coudurier-Curveur and her colleagues studied one particularly fracture riddled region of the India-Australia-Capricorn plate near the Andaman-Sumatra subduction zone. They used seismic reflection imaging and multibeam bathymetry, which involve bouncing sound waves off sediments and measuring the returning signals, to look for structures at and below seafloor consistent with an active fault.

    Along one giant crack that the team dubbed F6a, Coudurier-Curveur and her colleagues found 60 pull-apart basins, characteristic depressions that can form along strike-slip plate boundaries. The team showed that the basins followed a long, linear track that passed near the epicenters of both of the 2012 earthquakes.

    “It’s at least 1,000 kilometers,” said Coudurier-Curveur. “It might be even longer, but we don’t have the data to show where it extends.” This feature, the team surmised, was consistent with being a plate boundary. An important next step was to estimate its slip rate.

    Slower Than San Andreas

    To do that, the scientists relied on two quantities: the length of the largest, and presumably oldest, pull-apart basin (roughly 5,800 meters) and the duration of the most recent episode of fault activity (roughly 2.3 million years). By dividing the length of the pull-apart basin by this time interval, they calculated a maximum slip rate of about 2.5 millimeters per year. That’s roughly tenfold slower than the rate along other strike-slip plate boundaries like the San Andreas Fault but not much slower than the slip rates of the Dead Sea Fault and the Owen Fracture Zone, the team noted.

    On the basis of that slip rate, Coudurier-Curveur and her collaborators estimated the return interval for an earthquake like the magnitude 8.6 one reported in April 2012. Assuming that such an event releases several tens of meters of coseismic slip, a similar earthquake might occur every 20,000 years or so, said Coudurier-Curveur. “Once you release the stress, you need a number of years to build that stress again.”

    These results were published in March in Geophysical Research Letters.

    These findings are convincing, said Kevin Kwong, a geophysicist at the University of Washington in Seattle not involved in the research. “What we see in this region in the middle of the ocean is very analogous to other plate boundary regions.”

    But continuing to monitor this part of the seafloor for earthquakes is also important, he said, because temblors illustrate plate boundaries. That work will require new instrumentation, said Kwong. “We don’t have the seismic stations nearby.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 11:37 am on March 20, 2020 Permalink | Reply
    Tags: "U.S. Readies Health Response for the Next Big Eruption", , , Eos, , Mount St. Helens spawned a new field of science concerned with the health impacts of volcanoes in the short and long term., Volcano experts meet regularly to discuss eruption forecasting and hazard modeling.,   

    From Eos: “U.S. Readies Health Response for the Next Big Eruption” 

    From AGU
    Eos news bloc

    From Eos

    12 March 2020
    Kimberly M. S. Cartier

    Forty years after the explosive eruption of Mount St. Helens, scientists, communities, and civic officials are evaluating plans to best protect public health before, during, and after an eruption.

    1
    A Plinian eruption column billows from Mount St. Helens on 18 May 1980. Credit: USGS/Robert Krimmel.

    Whakaari volcano in New Zealand erupted on 9 December 2019. Although experts had warned for weeks that the stratovolcano was showing signs of unrest, Whakaari remained open to tourism. Forty-seven people were reported to have been on Whakaari, or White Island, when the eruption happened. Twenty-one people have died.

    A month later, Taal volcano in the Philippines erupted and spewed a 15-kilometer tall ash plume into the sky. Lava fountains, sulfuric gas, volcanic earthquakes, and more ash plumes followed. Nearly half a million people lived within the 14-kilometer radius danger zone, but only about 70,000 of those people are estimated to have sheltered in evacuation centers. The price of certified breathing masks inflated tenfold after the eruption. The Philippine Department of Agriculture estimated that ash has destroyed roughly US$60 million in crops. Some residents of Taal have lost everything.

    “We live on a very, very active planet volcanically speaking,” said Janine Krippner, a volcanologist at the Smithsonian Global Volcanism Program in Washington, D.C. “Those types of volcanoes and the eruption styles that we’ve seen now could absolutely happen in the United States in a wide range of sizes—from White Island being very small [to] Taal being a moderate eruption which has the potential to be bigger,” she said.

    It has been 40 years since Mount St. Helens in Washington state erupted. On 18 May 1980, the event killed 57 people, including a volcanologist monitoring the ongoing activity. Since then the volcano experienced some sustained eruptive activity between 2004–2008, largely creating a lava dome beneath the surface, but occasionally sending up some ash. That means it’s been 40 years since U.S. agencies have had to coordinate to keep a major eruption on the mainland from becoming a public health crisis—and experts have found that it’s long past time for a more modern game plan.

    It’s About Who You Know…

    A lot of recent interagency work has focused on bringing volcano response plans in line with the newest science, response structures, and communication platforms.

    Regional and state emergency divisions have kept an ongoing dialogue with the Cascades Volcano Observatory (CVO) on the hazards specific to their areas. The National Science Foundation, NASA, the U.S. Geological Survey (USGS), and the National Academies of Sciences, Engineering, and Medicine conducted a 2-year investigation about how to improve eruption forecasting. Volcanologists, too, have been developing a research coordination network to organize scientific investigations of an eruption, which will inform future response plans.

    In 2018, the eruption of Kīlauea in Hawaii became a proving ground for some of these new response networks.

    3
    Lava bursts from a fissure on the flanks of Kīlauea volcano. As new lava flows and as Kilauea evolves, new landscapes in southeastern areas of the island of Hawai‘i are beginning to take shape. Credit: Mario Tama/Staff/Getty Images News/Getty Images

    Local response teams, USGS, the Federal Emergency Management Agency, and scientists worked together to gather and disseminate information to affected populations. Many of those involved consider the overall response a great success.

    Volcano experts meet regularly to discuss eruption forecasting and hazard modeling. But there’s still more work to be done in understanding the health risks form volcanoes and coming up with action plans to mitigate those risks.

    In the current framework, response would start at the city level, the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry (CDC ATSDR) told Eos in a statement. “Local authorities could declare an emergency or disaster and likely would request state assistance. The governor of the state would request federal help if needed. The state request could prompt a presidential declaration and the National Response Framework would activate under the Federal Emergency Management Agency (FEMA).” The National Response Framework, a federal guide to disaster and emergency response, was not in place when Mount St. Helens erupted but has since been used to guide the response to eruptions in Alaska, Hawaii, and the Philippines, ATSDR said.

    “At the eruption of Mount St. Helens in 1980…there were many agencies and thousands of individuals involved in all aspects of the disaster,” explained Peter Baxter, a volcano health expert at the University of Cambridge in the United Kingdom. Baxter, who was part of the response team in 1980, said that the eruption was an “unknown entity” in terms of the human health impacts and the practical challenges of ash deposits in community.

    “People had to learn from scratch,” he said. “Although some of the lessons have been relearned at other volcanoes around the world since, a lot of valuable practical experience is being lost as people retire.”

    “When you do disaster response work, you want to have relationships in place,” said David Damby, who researches the health impacts of eruptions at the USGS California Volcano Observatory in Menlo Park. “During a crisis it’s really hard to meet people and spin up a working relationship on the spot.” If an emergency manager needs a particular piece of information about an ongoing disaster, he said, the key to responding quickly is knowing ahead of time who holds that information.

    …And Also What You Know

    Before the Mount St. Helens event, the last time a major volcano had erupted in the conterminous United States was the 1914 Lassen Peak eruption in California. Unlike the very active volcanoes in Hawaii and Alaska, active volcanoes in the rest of the country erupt twice a century on average. That makes it difficult to predict the potential health hazards that stem from any one specific volcano.

    Mount St. Helens spawned a new field of science concerned with the health impacts of volcanoes in the short and long term. As far as case studies go, that eruption is still one of the most extensively studied to date, but it’s still just one example of the type of eruption that might take place. Volcanologists, out of necessity, study examples from around the world to learn more about what the next Cascades eruption might look like.

    “There was an eruption of El Chichón in 1982 in southern Mexico, and 1,500 people died from pyroclastic flows,” said Carolyn Driedger. “People were not organizing. They had not built trusting relationships with their local communities at risk.” Driedger, a hydrologist and outreach coordinator at CVO in Vancouver, Wash., also witnessed and responded to the Mount St. Helens eruption.

    Then came the eruption of Nevado del Ruiz, Colombia, in 1985 and the Armero tragedy, in which more than 20,000 people in the city of Armero died as a result of mudflows issuing from the eruption.

    “Scientists came into [Armero] and tried to talk to local people, but…they weren’t trusted,” Driedger said. “There were vested business interests that were interfering with the messaging. The lahar came through.”

    A lahar is a volcanic mudflow, Driedger explained. “It’s debris and mud and boulders and anything the flow can pick up and carry.”

    “It was just your worst nightmare,” she said. “It was a dark and stormy night, 11:30 at night, when the lahar came through; 25,000 people died. That showed us lahars are huge hazards and getting information about these hazards to people is so important.”

    From the 1991 eruption of Pinatubo, Philippines, “we learned a lot about eruption prediction and how lahars can affect areas for generations after the initial occurrence,” Driedger said. “Now we know it’s not over when it’s over.”

    Other scientific disciplines aid volcanic research, too. “There’s been a lot done on anthropogenic pollution, for example,” Damby said. “Understanding the impact of particulate matter on people’s health is something that we’re really tuned into because volcanic ash, at the end of the day, is particulate matter.”

    Volcanologists have spent decades building a body of knowledge about how a volcanic eruption might make people sick. That knowledge can be of critical use to agencies and health professionals who don’t exclusively deal with volcanoes.

    “If you’re a health professional who’s never dealt with a volcanic eruption before—which anyone in the U.S. who didn’t respond to 1980 Mount St. Helens is in that same boat—then it’s nice to be able to have the USGS say, ‘Here’s what we know. Here’s what problems might be. Here’s what we need to test for,’” Damby said.

    Evolving Eruptions

    However, predicting an eruption’s hazards is not as easy as saying “Volcano X will produce Hazard X” and “Volcano Y will produce Hazard Y.”

    “Volcanic eruptions can evolve,” Krippner said. “They can get bigger or smaller, or they can pause and then continue. The different hazards can change through that time as well and the extent of those hazards.”

    Disaster mitigation plans work best when the people at risk understand those risks. “There are areas which are excelling at this, but generally speaking, every single aspect of volcanism seems to be misunderstood,” she said.

    For example, simply using the word “smoke” instead of “ash” implies a different set of health hazards and protection measures. “I’d say everything—the terminology, what the hazards are, what they mean for people, what the impacts to people actually are, and how people can stay safe—every single aspect of volcanology has to be better understood by the community,” said Krippner. She noted that official communications about the 2018 Kīlauea eruption were superb.

    “What we focus on the most, because it puts the most people in immediate harm’s way, is lahars,” said Brian Terbush, who heads the earthquake and volcano program at the Washington State Emergency Management Division.

    “All of our volcanoes have a lahar potential and especially the larger ones with huge glacier cover that have river drainages that go into populated areas, such as Mount Rainier,” Terbush said. “About 80,000 people could potentially be at risk from the lahars.” That’s just those at risk from the most immediate lahars near Mount Rainier, Terbush said. Downriver lahars, some experts say, could endanger more than 100,000 residents, employees, and tourists.

    “They are highly destructive,” Driedger added, “so it’s maybe less a health hazard and more a matter of life and death as to your getting out of the way.”

    4
    An eruption of Mount Rainier would cause lahars to sweep through the surrounding area and toward the Puget Sound. Many of the cities at risk for lahars plan and practice evacuation routes. Credit: USGS

    And then, of course, there is volcanic ash. “When ash falls, everything that is covered is impacted and that includes the air,” she said. “Most of the time ash is a nuisance to people, but the people who already have compromised breathing are at risk just as they would be in a place with dense pollution or smoke in the air or a dust storm.”

    Volcanologists and emergency responders are using ash dispersion models, like Ash3d, more often. These models use weather data from the National Oceanic and Atmospheric Administration (NOAA) to predict what areas might experience ashfall. Information from NOAA is also needed after an eruption has ended, when ash can be resuspended in the air by wind and continue to endanger people with compromised breathing.

    “When an eruption is developing, it’s a very confusing time,” Krippner said. “There’s a lot of conflicting information. Scientists are figuring out what exactly is happening, how big this eruption might be, and what areas are being impacted. The groundwork needs to be done beforehand.”

    It’s Not Over When It’s Over

    There’s still a lot of work to be done assessing the long-term health impacts of an eruption, including the secondary health impacts that can occur long before or long after an eruption.

    The sometimes-prolonged period of anticipation preceding an eruption can affect the mental health of emergency managers and the at-risk population. “Even before the lahar even happens…there’s the mental stress of knowing what can happen in your beloved community. I don’t discount that as a medical issue,” Driedger said.

    Sometimes eruptions build up slowly over months, Terbush added, but sometimes they can escalate in a matter of hours (as happened with Taal). For emergency managers, “just the unpredictability of what’s actually going to happen in an eruption, unpredictability in the timeline and unpredictability of which hazards are going to be impactful… if people are activated and responding, especially media response for all that time, that is going to wear on everybody involved.”

    And then there are the myriad of ways that ashfall, lahars, and, to a lesser extent, lava flows, damage critical infrastructure that protects public health. “All the health issues related to relocations—not just temporary evacuation but in many cases final relocation—all those health issues, mental and physical, are applicable with lahars,” Driedger said.

    Ashfall and lahars can cause power outages and leave hospitals and at-home medical devices without power. Wet ash slicks roads and reduces visibility, which can lead to car accidents. Ash can damage a plane’s jet engines, which can hinder evacuation and relief efforts, she added. Local transit authorities, the U.S. Department of Transportation, or the National Guard might aid an evacuation.

    Toxic salts, or leachates, can form on ash while its still in the plume and then wash out into groundwater after ashfall. Livestock that eat contaminated grass or soil can get sick or die.

    “It’s easy to just say ash is ash is ash,” Damby said. “But depending on the composition of the volcano that it erupted from, each ash sample will differ from every other ash sample erupted at a different volcano.” Ash particles around 2.5 and 10 micrometers in size are particularly bad for respiratory health.

    Lahars sweep away bridges, buildings, cropland, and forests, and they can also threaten the local water supply for years. “Lahars are the lasting legacy of volcanic eruptions,” Driedger said. Lahar damage to water treatment plants can lead to higher disease rates. Sediment that is resuspended in water and moved down the valley can keep land unsuitable for settling for generations, she said. Agencies like the CDC, National Institutes of Health, U.S. Department of Agriculture, and Environmental Protection Agency might be called upon to assess land and water toxicity and help recovery efforts.

    And although lava generally moves slow enough that people can get out of the way, lava flows “can gobble up plenty of good orchard and agricultural space that can impact people,” Driedger added. “When you impact personal economies or the economy of the community, you are impacting the health of the people within it.”

    Plan, Practice, Educate, Communicate

    In the time between the recent Whakaari and Taal eruptions, there were actually dozens of volcanoes erupting around the world. “So to only have two making the news in a month or so shows you how little people are actually aware of the amount of activity we have on this planet,” Krippner said.

    Moreover, the unpredictability of eruption hazards presents a challenge for putting together an effective response plan, Terbush said. “Overall, there’s been a shift at the county and local levels with the recognition that any volcanic disaster is going to affect every area a little bit differently.” In areas that were affected by Mount St. Helens and those in the possible path of lahars, there is a cultural awareness of the dangers people might face.

    “The city of Puyallup has been excellent [in volcano readiness],” Terbush said. “This is one of the [municipalities] immediately in Mount Rainier’s lahar zone. This past year they evacuated 9,000 students, did a full school drill of 20 schools.” The drill, which took place on 17 May 2019, was the largest volcano evacuation drill in U.S. history.

    Volcano hazard work groups throughout the Cascade region bring emergency managers from local, regional, state, and tribal areas together with volcano experts to develop coordinated action plans. More cities every year practice lahar evacuation plans like Puyallup’s. Regional volcano observatories work with policy makers to make land use decisions that consider volcano hazards.

    But Driedger argues that volcano awareness and preparedness cannot end at the borders of Washington and Oregon. “Volcanic eruptions are pretty much out of the modern-day person’s personal experience,” she said. “Earthquakes you can feel—you know what a rumble is. You understand the concept of flooding or of a wind storm or a snow storm. But with volcanoes, they’re so multifaceted. It takes an extra amount of effort for us to talk about it with people and get them to understand. They fail to recognize that an eruption in Alaska can affect them in Wisconsin.”

    “We live in such a global society now, too,” she added. “People come to volcanic areas, and they don’t understand what the threats are….It’s the residents and it’s people who visit there, and it’s the taxpayers who are all funding risk reduction measures in some way or another.”

    Raising the base-level understanding of volcano hazards, Krippner said, will also go a long way toward combating the deluge of misinformation that spreads around the globe at lightning speed. In a crisis, finding good information fast saves lives.

    “If we have more sources of information that are consistent, easy to find, and [distributed] in more ways,” Krippner said, “and if we have people with larger followings out there that can point to these things rapidly, I think that would begin to solve the problem.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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.

     
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