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  • richardmitnick 10:47 am on June 25, 2017 Permalink | Reply
    Tags: , Deep Carbon Observatory (DCO) Summer School, Eos, Studying Yellowstone by Integrating Deep Carbon Science, , Yellowstone’s tectonic magmatic hydrothermal and microbial processes and their controls on carbon dioxide flux   

    From Eos: “Studying Yellowstone by Integrating Deep Carbon Science” 

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    23 June 2017
    Shaunna M. Morrison
    Mattia Pistone
    Lukas Kohl

    Second Deep Carbon Observatory Summer School; Yellowstone National Park, Montana and Wyoming, 23–28 July 2016.

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    Phormidium, a genus of orange, carotenoid-producing cyanobacteria, thrives in the outflow of Yellowstone’s Grand Prismatic hot spring. Deep Carbon Observatory (DCO) Summer School participants studied the conditions that are conducive to microbial life using published data and measurements acquired in Yellowstone National Park. Credit: Heidi Needham.

    Yellowstone National Park is a fascinating natural laboratory for geoscientists and biologists alike. Its steaming geysers and hot springs have been extensively studied to characterize the underlying hydrothermal activity. Scientists have also focused on microbial mat populations in extreme and hostile ecological niches with temperatures near boiling and pH from less than 1 to greater than 9. Yet little is known about the source of Yellowstone’s highly variable carbon fluxes.

    With this in mind, 38 early-career geologists, geochemists, microbiologists, and informaticians from 16 countries ventured to Yellowstone National Park for the Second Deep Carbon Observatory (DCO) Summer School in July 2016. Their goal was to study the complex interplay between the geosphere and biosphere, the effect of this interplay on the carbon-containing gases emitted by the Yellowstone volcanic system, and influences of high- and low-temperature fluids on microbial habitability through time and space.

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    Deep Carbon Observatory Summer School participants study a hot spring in Yellowstone National Park to observe the brightly colored microbial colonies that thrive in this extreme environment. Credit: Katie Pratt.

    The DCO Yellowstone short course consisted of three components:

    Fieldwork: Participants studied rock unit relationships, microbial mat communities, and hydrothermal fluid chemistry, and they made in situ carbon dioxide flux measurements.

    Classroom: Experts lectured and led discussions on the deep carbon cycle, extreme microbial systems, mineral evolution, the origin of life, geochemistry of gas fluxes, and fluid-rock interactions.

    Science presentations: Students presented their current research as fast-paced 1-minute lightning talks, followed by a poster session. Student abstracts can be found on the DCO website.

    Interdisciplinary and integrative science is essential to understanding complex systems: the ecology of extreme environments, intracontinental volcanism, and the deep carbon cycle. Participants faced the challenge of reconciling differences not only in subject matter but in temporal and spatial scales across their widely varying scientific domains. By the end of the session, DCO Summer School participants had integrated differing concepts of time and depth, fields of study, and technical experience to examine Yellowstone’s tectonic, magmatic, hydrothermal, and microbial processes and their controls on carbon dioxide flux.

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    At the summer school, participants learned about the geologic temperature (T) and pressure (P) regimes that can support microbial life (white areas). Credit: Mattia Pistone.

    Using published data and measurements acquired in the field, DCO Summer School scientists conducted a study on the conditions suitable for microbial life on Earth during the short course. The understanding they gained about the regimes in which life can interact with geologic materials and processes will enable these researchers to deepen their scientific studies and recognize fruitful cross-disciplinary collaborations.

    The DCO Summer School participants are continuing to build on the work they began in Yellowstone by asking questions that address long-standing unknowns in the scientific community. Such questions include the following: What are the sources and timing of the accumulation of Earth’s volatiles in Yellowstone? What are the geochemical and geophysical contexts of organic compound synthesis that predated the emergence of life? How deep is life found in the Earth’s interior? What are the fluid flux conditions that sustain life, as well as the hydrosphere and atmosphere, on Earth?

    The DCO is an interconnected community, and Summer School participants provide research updates at annual meetings, on the DCO website, and to various DCO committees. The authors thank the DCO Summer School organizers, instructors, and fellow participants as well as the DCO, American Geosciences Institute, the Center for Dark Energy Biosphere Investigations, Nano-Tech, and MO BIO Laboratories for their support.

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    The Grand Prismatic hot spring in Yellowstone National Park is one of the largest hot springs in the world. It owes its brilliant color gradient to changes in microbial populations with temperature. Credit: Daniel Petrash.

    See the full article here .

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  • richardmitnick 4:17 pm on June 9, 2017 Permalink | Reply
    Tags: Active volcanic lake research and monitoring, , An Autonomous Boat to Investigate Acidic Crater Lakes, , Bathymetric data, Determining the depth profile of these lakes, Eos, Poás volcano in Costa Rica,   

    From Eos: “An Autonomous Boat to Investigate Acidic Crater Lakes” 

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    5 June 2017
    Donald A. McFarlane
    dmcfarlane@kecksci.claremont.edu
    Joyce Lundberg
    Guy van Rentergem
    Carlos J. Ramírez

    A novel aquatic drone ventured into highly acidic waters to test the feasibility of remotely exploring and surveying hazardous volcanic lakes.

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    An autonomous, sonar-equipped boat is carried to the edge of the highly acidic water of Laguna Caliente, located in the crater of Poás volcano in Costa Rica, to test the craft’s ability to collect bathymetric data. Credit: Donald McFarlane

    In 1986, Lake Nyos in Cameroon exploded, jetting water more than 100 meters into the air as roughly 1.2 cubic kilometers of carbon dioxide suddenly belched from the waters. This enormous wave of gas smothered the surrounding countryside, killing more than 1700 people.

    The deadly eruption focused attention on the dangers posed by active volcanic crater lakes and the importance of monitoring such lakes for changes in volume and other factors. About 35 such lakes dot the Earth, but monitoring active volcanic lakes can be problematic, especially when they undergo frequent eruptions of steam and other gases. These eruptions can make them too dangerous for human inspection by inflatable boat or raft.

    However, the recent burgeoning interest in autonomous aerial drones presents researchers with an opportunity. So we asked ourselves, Could a small, inexpensive, and easily transportable autonomous boat, equipped with sonar, do the job?

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    The drone boat speeds off to survey the acid crater lake Laguna Caliente in Costa Rica’s Poás volcano. The lake has a pH of 0.53 and a temperature of 55°C. Credit: Donald McFarlane

    A Need to Determine Lake Volume

    A key aspect of active volcanic lake research and monitoring is the determination of lake volume, something that can change significantly as geothermal heating and evaporation, steam and gas eruptions, and sedimentation progress. As a result, considerable attention has been paid to determining the depth profile of these lakes.

    We designed and built an autonomous boat with that function in mind, using readily available and relatively inexpensive aerial drone components, open-source software, and a retail sonar unit. In total, the equipment used to create the boat cost roughly US$700

    Drone Boat Specs

    Our drone boat, which we dubbed a sonar-ASV (autonomous surface vehicle), has a hull with a catamaran design. Made from acrylonitrile butadiene styrene (ABS) plastic, it measures just 54 × 38 × 22 centimeters and weighs less than 10 kilograms. The ASV is easily carried in airline baggage or in a backpack across challenging terrain.

    Because the ASV has to work in highly acidic environments, we couldn’t use a conventional propulsion system with a drive shaft connected to a propeller in the water. The metal shaft would not survive the acidity. Instead, our ASV has an air propeller powered by a battery-driven electric motor.

    The boat is surprisingly agile and has a cruise speed of 0.8 meter per second (3 kilometers per hour), balancing high sonar resolution against minimal mission time.

    At cruise speed, the motor draws only 1.6–3.5 amps, depending on wind direction. Keeping the electric current low is important because high currents could lead to excess heating, which could be problematic because the ASV already has to operate in water temperatures of 55°C and higher.

    Craft Autonomy

    From the beginning of the design process, it was clear that the craft needed to be fully autonomous. For one thing, clouds of fog often obscure the hot lake surface, so the ASV needs to find its way on its own. Autonomous navigation also allows us to repeat the same track on subsequent missions if we want to focus on particular features of the lake bottom.

    We ended up choosing the open-source ArduPilot system for autopilot navigation. For planning the ASV forays, we used Windows-based Mission Planner software. An Arduino data logger board captured and stored data from the GPS, sonar, and additional sensors (such as temperature).

    Costa Rica Test Site

    Poás volcano in Costa Rica provided us with an ideal test site. At 2708 meters in elevation, Poás is topped by two crater lakes. The older lake, Laguna Botos, is an inactive, cold-water lake with near-normal chemistry. The other, Laguna Caliente, is a hyperacidic, hot, and very active lake with chemistry that is anything but normal.

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    Scientists hike down to Laguna Caliente. Credit: Joyce Lundberg

    We deployed the ASV into Laguna Caliente on 30 and 31 July 2016. During these runs, we recorded a pH of 0.53, roughly 3 times the acidity of battery acid, and a water temperature of 55°C. Moreover, during the course of our fieldwork, the lake experienced small- to medium-sized steam eruptions every 35–45 minutes.

    Visibility was also poor. The ASV was rarely visible through clouds of condensation during its Laguna Caliente mission. In total, the device made two runs into the lake, each for about 45 minutes. Fieldwork at the lake took place over 3 days, stretching to 1 August, with the third day reserved for recovery of the vehicle.

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    On 31 July 2016, a nearby steam eruption caused waves that inundated the drone boat as it crossed Laguna Caliente. The ASV was recovered but was coated with elemental sulfur and electrically crippled, as seen here. Nonetheless, it still delivered its data. Credit: Joyce Lundberg

    Surviving an Acid Bath

    Our boat proved remarkably rugged. On 31 July, a nearby steam eruption inundated the roving ASV with hot, highly acidic water. Although the acid penetrated a poorly sealed cable connection and shorted out the telemetry system, the ASV survived, was recovered, and delivered its data.

    The eruption took place at the end of the vehicle’s second mission. The vehicle was not operable after its acid bath but has since been rebuilt.

    A Valuable Tool

    In the end, the ASV missions provided the bathymetric data we needed to map the bottom of Laguna Caliente and thus calculate its volume.

    On 13 April, Laguna Caliente erupted, spewing water, steam, and sediment as high as 1 kilometer into the air. As the eruption developed, new ash and incandescent pyroclastics were ejected until at least 26 April, when the activity destroyed a camera operating at the site. These eruption events have completely restructured the lake, and our team hopes to return in the near future for another series of lake surveys.

    Such rapid mobilization is possible with inexpensive and easily portable equipment like our ASV. Through custom-built ASVs equipped with sonar and other sensors, scientists can gain a valuable new tool for the exploration and monitoring of remote and hazardous volcanic lakes.

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    Bathymetric map of Laguna Caliente on Poás volcano, August 2016. Credit: Guy van Rentergem

    Acknowledgment

    Partial funding was provided by the Keck Science Department of the Claremont Colleges.

    Author Information

    Donald A. McFarlane (email: dmcfarlane@kecksci.claremont.edu), W. M. Keck Science Department, The Claremont Colleges, Claremont, Calif.; Joyce Lundberg, Department of Geography and Environmental Studies, Carleton University, Ottawa, Ont., Canada; Guy van Rentergem, Koningin Astridstraat, Deinze, Belgium; and Carlos J. Ramírez, Centro de Investigaciones Geofísicas, Universidad de Costa Rica, San Jose

    See the full article here .

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  • richardmitnick 4:36 pm on June 8, 2017 Permalink | Reply
    Tags: , , , , Eos, Instrument Development Enables Planetary Exploration   

    From Eos: “Instrument Development Enables Planetary Exploration” 

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    6.8.17
    Sabrina M. Feldman
    David Beaty
    James W. Ashley

    Third International Workshop on Instrumentation for Planetary Missions; Pasadena, California, 24–27 October 2016

    1
    This laser-interrogated microfluidic chip (10 centimeters in diameter) is one of the new planetary instrument technologies that NASA and other space agencies are developing to search for chemical indicators of life on other worlds. In this lab-on-a-chip device, a laser excites labeled amino acid molecules as they pass through a microchannel. Different amino acid types pass through the channel at well-defined speeds, enabling their identification. Credit: Fernanda Mora and Amanda Stockton, Microdevices Laboratory, Jet Propulsion Laboratory, California Institute of Technology

    The scientific knowledge gained from future planetary exploration missions will depend critically on the capabilities of instruments (cameras, spectrometers, magnetometers, thermal sensors, seismometers, remote laboratories, and other robotic tools) that acquire sensory information in lieu of human explorers. The flight opportunities available to planetary instrument developers depend on a complex interplay among mission science requirements; technology capabilities; mass, power, and volume constraints; planetary geometries; and funding availability.

    Last October, more than 195 engineers, scientists, technologists, and program managers, representing 12 countries, met in California for the third workshop in a series that began in 2012 at the Goddard Space Flight Center and has been held every 2 years since.

    The workshop provided a forum for collaboration, team building, exchange of ideas and information, and the presentation of status reports for instruments, subsystems, and other payload-related technologies needed to address planetary science questions. Oral and poster sessions were based on 136 submitted abstracts.

    Panel sessions were organized around three themes:

    perspectives on the future of planetary exploration
    bridging the gap between planetary scientists and instrument developers
    lessons learned for instrument development at various technology readiness levels (TRL 1–9)

    The “perspectives” panel addressed planetary science priorities and opportunities over the next several decades for planetary instruments on missions to Mars, the Moon, Mercury, Venus, small bodies, and the outer planets. Panel participants strongly supported existing technology development programs, including NASA’s Planetary Instrument Concepts for the Advancement of Solar System Observations (PICASSO) and Maturation of Instruments for Solar System Exploration (MatISSE) [there is a link for this, but the message comes up “The website tried to negotiate an inadequate level of security.
    astrobiology.nasa.gov uses security technology that is outdated and vulnerable to attack. An attacker could easily reveal information which you thought to be safe. The website administrator will need to fix the server first before you can visit the site.
    Error code: NS_ERROR_NET_INADEQUATE_SECURITY.]

    The panel emphasized that innovative approaches enhance mission science return, but new technology development efforts must effectively address cost and technical risk concerns, provide clear advantages over currently existing capabilities, and take into account mission schedules. They agreed that emerging low-cost demonstration platforms (e.g., planetary CubeSats and SmallSats) provide invaluable opportunities to help new planetary instrument technologies mature and reduce the development risk in transitioning them to larger missions.

    The “bridging the gap” panel emphasized the importance of scientists, technologists, and engineers connecting at meetings. These groups must be willing to consider partnerships with private industry, learn new roles, and become fluent in disciplines outside of their formal training.

    The panel on “lessons learned” covered past instrument development efforts for technology readiness levels (TRLs) from stage 1 (conceptual) to 9 (flight proven). These lessons included the importance of development teams beginning to think early in the development process (TRLs 3–5) about planetary protection considerations, environmental and operational constraints, systems engineering, and data analysis and operational constraints. Instrument development teams at all TRL stages should include scientists (to provide the “why”) and engineers (to provide the “how”) on instruments and missions.

    The panels also highlighted the value of strong teams with a mixture of backgrounds in science, technology, management, components design, and experience with working on various types of teams. Mentoring programs are vital to passing this knowledge along to early-career scientists. Finally, the panels noted that instrument development is becoming more international; thus, researchers must learn to function within one another’s cultures.

    End-of-workshop feedback mentioned the difficulty in getting scientists and instrument engineers together at the traditional conferences and recommended that the community should seek ways to expand networking opportunities. For example, instrument talks could be incorporated into the annual Lunar and Planetary Science Conference.

    More details on the presentations are available in the workshop abstracts. The workshop also produced an open-source online instrument database to facilitate ongoing input from developers.

    The workshop was sponsored by the Lunar and Planetary Institute. The next workshop in this series is tentatively scheduled to take place in Berlin, Germany, in the fall of 2018.

    —Sabrina M. Feldman, David Beaty, and James W. Ashley (email: james.w.ashley@jpl.nasa.gov), Jet Propulsion Laboratory, California Institute of Technology, Pasadena

    See the full article here .

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

     
  • richardmitnick 2:48 pm on May 26, 2017 Permalink | Reply
    Tags: , , Eos, , Paleoceanography and Paleoclimatology   

    From Eos: “A Sea Change in Paleoceanography’ 

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    22 May 2017
    Ellen Thomas
    ellen.thomas@yale.edu

    After 32 years of existence, the journal Paleoceanography is changing its name. On January 1, 2018, it will become Paleoceanography and Paleoclimatology. This reflects the growth, expansion and evolution of a field of research over the years, and is not a major change of course, nor a break with the journal’s history.

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    In 1986, Jim Kennett, Paleoceanography’s founding editor, asked for contributions dealing with all aspects of understanding and reconstructing Earth’s past climate, biota and environments, while emphasizing global and regional understanding. At the time, such research papers were based dominantly on the marine sedimentary record, with study materials commonly supplied by scientific ocean drilling.

    Since then, the technologies of sampling, sample analysis, data analysis and model development have evolved greatly and rapidly. Articles in Paleoceanography today routinely compare and combine proxy records from ice cores, speleothems, terrestrial sediments and/or lake deposits with multiple stacked proxy records from marine sediment cores, while data are integrated into a broad spectrum of geochemical, earth system, ecosystem and climate models.

    The process of recognition of this de-facto expansion in scope of Paleoceanography has taken a few years. It was started in 2014 by then Editor-in-Chief, Chris Charles, who announced in Eos that the journal was expanding to ‘embrace all aspects of global paleoclimatology’. The journal’s name was amended (informally) to “Paleoceanography: An AGU Journal exploring Earth’s Paleoclimate.” New Associate Editors with a broad variety of expertise joined the editorial board.

    Finally, after discussions at the 2016 AGU Fall Meeting, the leadership of the AGU Focus Group Paleoceanography & Paleoclimatology, together with the journal editors, organized a survey to gauge the community’s opinion. A large majority (~65%) of the 751 respondents was in favor of a change in the name of the journal.

    Inserting the word ‘climate’ into the name allows us to celebrate the growth and evolution of our scientific undertaking. Understanding climates of the past has been an integral part of earth sciences since their early days. Lyell (1830–1833) devoted three chapters in ‘Principles of Geology’ to cyclically changing climates (as shown by fossil distributions), influenced by the position of the continents: the present as key to the past. Chamberlin (1906) wondered how Earth’s climate could have remained sufficiently stable to allow life to persist, ‘without break of continuity’, writing that ‘On the further maintenance of this continuity hang future interests of transcendent moment’. With foresight, he argued that for such continuity to persist ‘a narrow range of atmospheric constitution, notably in the critical element carbon dioxide, has been equally indispensable’.

    In the near future, we may move outside the range of concentrations of atmospheric CO2 as they have been for tens of millions of years, as documented in a number of papers using various proxies, with quite a few of these published in Paleoceanography. We now use, in addition to fossils, a broad and growing range of stable isotope compositions, trace element concentrations and organic biomarkers in fossils and sediments as quantitative proxies for a growing number of environmental properties (e.g., temperature, oxygenation, pH, pCO2).

    In our present time of environmental change, it is, more than ever, important to use proxy data on Earth’s past in order to evaluate Earth’s future, thus making our past a key guide to our future.

    Paleoceanography has always aimed to publish thorough, innovative studies which add to our understanding of the planet on which we live, and the past variability in its environments over the full range of Earth history. It will continue to do so under its new name. Any paper submitted after July 1, 2017 will be considered under the new title, and all papers accepted after December 1, 2017 will be published under the new title.

    See the full article here .

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  • richardmitnick 12:23 pm on May 23, 2017 Permalink | Reply
    Tags: , Cosmic Muons Reveal the Land Hidden Under Ice, Eos, ,   

    From Eos: “Cosmic Muons Reveal the Land Hidden Under Ice” 

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    5.23.17
    Jenny Lunn
    jlunn@agu.org

    Scientists accurately map the shape of the bedrock beneath a glacier using a new technique.

    1
    Aletsch glacier seen from Jungfraujoch. A tunnel runs through the bedrock below this glacier; researchers placed sensors within this tunnel to help map the shape of the bedrock under the ice. Credit: Alessandro Lechmann

    The land surface under a glacier is sculpted and shaped by the ice passing over it. Data about the shape of the bedrock yield information crucial to understanding erosional processes underneath a glacier. However, the inaccessibility of sites where glacial erosion currently occurs presents big challenges for advancing this understanding.

    A range of techniques has been used to map the bedrock beneath glaciers, including drilling, seismic surveys, multibeam bathymetry, gravity measurements, and radio-echo soundings. The accuracy of results has been limited, so Nishiyama et al [Geophysical Research Letters]. tested a different technique: emulsion film muon radiography.

    2
    A muon detector in the Jungfrau railway tunnel awaiting arrival of the cosmic ray muons. Credit: Nishiyama et al.

    Muons are formed when cosmic rays collide with atoms in Earth’s upper atmosphere. They descend toward Earth, with about 10,000 muons reaching each square meter of Earth’s surface every minute. One of their significant properties is that they can pass through matter, even dense and solid objects on Earth.

    Particle detectors can be used to measure the quantity of muons and their trajectories, which can reveal information about the materials that they have passed through.

    Because cosmic muons travel only downward, detectors need to be located below the objects to be surveyed. This technique has been used by geophysicists to scan the interior architecture of volcanoes, seismic faults, and caves and to detect carbon leaks, but it has posed a challenge for surveying the bedrock beneath glaciers.

    The team of researchers found a solution in the central Swiss Alps: the Jungfrau railway tunnel, which runs through the bedrock beneath the Aletsch glacier. They set up three particle detectors in the tunnel that are oriented upward with a view of the bedrock beneath the base of the largest glacier of Europe.

    3
    Three-dimensional reconstructed bedrock shape (blue) under the uppermost part of the Aletsch glacier. The shape of the interface was determined from the cosmic ray muon measurement performed at three muon detectors (D1, D2, and D3) along the railway tunnel (gray line). Bedrock that pokes through ice is in gray tones. Jungfraufirn is a small glacier that feeds the Aletsch glacier. Blue dots on the gray line represent points where scientists sampled rocks within the tunnel. The image is Figure 5b in Nishiyama et al.; dashed lines outline a cross section of this 3-D map that can be found in Figure 5c. Credit: Nishiyama et al.; base map from SWISSIMAGE, reproduced by permission of swisstopo (BA17061)

    Different types of particle detectors are available for muon radiography, but the team selected emulsion films, a special type of photographic film that can be used in remote and harsh environments because it does not require any electric power or computers for operation.

    Because of the density contrast between ice and rock, the patterns of muons captured on the film over a 47-day period could be used to accurately map the shape of the bedrock below the glacier.

    Using this technique, the researchers were able to map the bedrock-ice interface beneath the glacier over a 4000-square-meter area. They were also able to infer the glacier’s response to global warming. In particular, the team predicts a larger frequency of rock avalanches as the ice shrinks, exacerbated by reconstructed bedrock geometry beneath the glacier. This increase is of particular concern because buildings are situated on top of the bedrock. These include tourist facilities, a research station, and communications infrastructure, as well as the railway tunnel itself, which cuts through the bedrock.

    The use of cosmic muon radiography is spreading in various fields, including geophysics and civil engineering. This first application of the technique in glacial geology complements data collected by other methods and has the potential to be applied in other glacial locations underlain by a tunnel. (Geophysical Research Letters, https://doi.org/10.1002/2017GL073599, 2017)

    See the full article here .

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

     
  • richardmitnick 12:01 pm on May 19, 2017 Permalink | Reply
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    From Eos: “Tornado Casualties Depend More on Storm Energy Than Population” 

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    5.18.17
    Katherine Kornei

    National Weather Service data from nearly 900 tornadoes and a principle of economics reveal the relationship between storm energy, population, and casualty count.

    1
    A scene of destruction in Concord, Ala., after the 2011 Tuscaloosa–Birmingham tornado caused more than 1500 casualties. A new study indicates that storm intensity is a better predictor of casualty counts than the size of the local population. Credit: National Weather Service

    When a dark, swirling funnel cloud dips toward the ground, people living in a U.S. region in and near the Great Plains popularly known as Tornado Alley know to move to a safe spot. Tornadoes can destroy concrete buildings and send railcars rolling, and these violent windstorms account for roughly 20% of natural hazard–related deaths in the United States.

    Despite tornadoes’ danger, the correlations among the number of storm-related casualties, a twister’s energy, and the size of the population in its path are not well understood. Better understanding of those relationships could help scientists, policy makers, and emergency management personnel predict future tornado deaths and injuries based on trends in population growth and tornado activity. Now researchers have used a principle of economics to show that a tornado’s casualty count depends more strongly on the energy of the storm than on the size of the local population.

    This study is “likely to spur conversation and additional research,” said Todd Moore, a physical geographer at Towson University in Towson, Md., not involved in the study. “It provides a framework that can be modified to include additional risk variables.”

    Fear Becomes an Obsession

    Tyler Fricker grew up hearing his father’s stories of the 1974 Xenia, Ohio, tornado that killed 33 people and injured more than 1000 others. Fricker, now a geographer at Florida State University in Tallahassee and the lead author of the new study, has also lived through a few tornadoes of his own. He explains his fascination with tornadoes as “fear becoming an obsession.”

    In the new research, he and his colleagues analyzed 872 casualty-causing tornadoes that swept through parts of the United States between 2007 and 2015. They defined “casualty” as a death or injury related to a storm. “By understanding tornado behavior better…we get a deeper understanding of what may be causing the death and destruction we see in these storms,” said Fricker.

    The team borrowed a principle of economics known as elasticity to investigate how a tornado’s casualty toll scaled with its energy and the size of the nearby population. Elasticity is commonly used by economists to investigate how two measurements—for example, supply and demand—are related.

    The researchers used National Weather Service data to determine the energy dissipated by a tornado. They calculated this energy as proportional to the area of a tornado’s path multiplied by its average wind speed raised to the third power. Knowing this quantity for each tornado allowed the team to uniformly define the intensity of each storm. The researchers then collected population measurements in roughly 1 × 1 kilometer squares for the path of each tornado using a database of world population maintained by Columbia University.

    Predicting Casualties

    Armed with these two measurements and the published casualty counts for each of the tornadoes in their sample, Fricker and his colleagues investigated how casualties scaled with storm energy and the size of the nearby population. The scientists found that storm energy was a better predictor of the number of storm-related injuries and deaths: Doubling the energy of a tornado resulted in 33% more casualties, but doubling the population of a tornado-prone area resulted in only 21% more casualties. These results, which the team reported last month in Geophysical Research Letters, can inform emergency planning, the team suggests.

    The relatively larger impact of tornado energy on casualties might be cause for concern, Fricker and his colleagues note. If climate change is triggering more powerful tornadoes, an idea that’s been suggested and debated, emergency managers might have to contend with larger casualty counts in the future. But scientists are by no means certain that larger tornadoes are imminent. “There is no doubt climate change is influencing hazards, but for tornadoes, we just simply don’t know to what extent yet,” said Stephen Strader, a geographer at Villanova University in Villanova, Pa., not involved in the study.

    It is “far more likely” that the population will double in the future rather than the tornado energy, notes Victor Gensini, a meteorologist at the College of DuPage in Glen Ellyn, Ill., who was not involved in the study. Effective communication and good city planning might help reduce storm-related casualties, Fricker and colleagues suggest. “It’s hard to control the behavior of tornadoes, but it’s somewhat within our control to smartly advance how we organize cities and suburbs,” said Fricker.

    Many More Factors

    Of course, changes in storm energy and population can’t fully explain all variations in storm-related deaths or injuries. “There are also more factors that combine to determine a casualty, one of the most important being what type of structure a person is in when the tornado strikes,” said Gensini.

    Fricker said he and his colleagues are looking forward to examining factors such as how a victim’s age, socioeconomic status, and race might correlate with vulnerability to harm from a tornado. “Maybe we’ll be able to profile communities more susceptible to casualties based on all of these other determinants,” said Fricker.

    The team hopes that their findings will be useful to emergency personnel, who could target these most vulnerable populations when they spread information about tornado preparedness, for example. After all, “you might have only 10 or 15 minutes to get to a safe spot,” said Fricker.

    See the full article here .

    Please help promote STEM in your local schools.

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  • richardmitnick 12:05 pm on May 8, 2017 Permalink | Reply
    Tags: , Competing Models of Mountain Formation Reconciled, , Eos,   

    From Eos: “Competing Models of Mountain Formation Reconciled” 

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    5.8.17
    Andy Parsons

    1
    View towards Everest Base Camp along the Khumbu Valley, central Nepal, with Pumori (7,161 m) on the left and Nuptse on the right (7,861 m). These rocks have been exhumed from mid-crustal levels where they once formed a weak viscous flow during the early development of the Himalaya. Credit: Andy Parsons

    Andy Parsons was recently awarded the 2017 Ramsay Medal by the Geological Society of London for his research article published in Geochemistry, Geophysics, Geosystems [Parsons et al., 2016]. The Ramsay Medal is an annual international award for the best publication in the field of tectonics and structural geology during the last year from a postgraduate or recent postgraduate. His study tested datasets against different models of mountain formation to explain the evolution of the Himalaya, resolving some long-standing arguments between advocates of competing models. Andy answers some questions about research in this field.

    The Ramsay Medal is an annual international award for the best publication in the field of tectonics and structural geology during the last year from a postgraduate or recent postgraduate. His study tested datasets against different models of mountain formation to explain the evolution of the Himalaya, resolving some long-standing arguments between advocates of competing models. Andy answers some questions about research in this field.

    How did the Himalayan mountain chain form?

    50 million years ago, tectonic plate motion caused India to collide with Asia. This movement has continued ever since, resulting in formation of the world’s largest mountain range; the Himalaya. Understanding the geological processes responsible for the formation of mountain belts is challenging and, for many years, researchers have been debating two seemingly incompatible ideas for the formation of the Himalaya: channel flow and duplex formation.

    The channel flow model proposes that the Himalaya formed by southwards horizontal flow of a weak mid-crustal layer. Flow was driven by the weight of the overlying thickened crust, similar to the squeezing of a tube of toothpaste. On the other hand, duplex formation involves vertical stacking of multiple layers of the crust in a similar fashion to a wedge of snow piling upward as it is pushed by a plow. This model requires strong and rigid crust with deformation occurring along planes of weakness that allow slices of the crust to slide over and on top of each other.

    The mechanical differences between these models led many researchers to believe that they were mutually exclusive, and arguments for and against both models have been equally strong. More recent research in the Himalaya is beginning to show that these models are not mutually exclusive but rather operate at different times and positions during formation of the mountain belt. Key to this reconciliation is the recognition that the mechanical properties of the crust can vary in both space and time during the development of large, long-lived mountain belts.

    What particular aspects of mountain formation are the focus of your research?

    During continental collision, crustal thickening and erosion leads to uplift and exposure of rocks that were once located tens of kilometers below the surface. These rocks preserve a record of deformation that occurred at depth as the mountain belt was forming. My research focuses on unraveling this record of deformation at the macroscale in mountain-sides and cliff exposures and at the microscale in hand samples and crystal lattices. In particular, I look at the temperature and depth at which different rocks and minerals deform in order to determine how spatial and temporal variations in the mechanical properties of the crust control the formation of mountain belts.

    How does your research contribute to a new understanding or synthesis?

    The Himalaya comprises domains of rocks deformed at high temperatures deep within the crust, juxtaposed against domains rocks deformed at lower temperature and shallower depths. In our recent study we investigate rocks of both types, looking particularly at how the preserved record of deformation changed within and between these domains. By understanding how different minerals deform at different depths and temperature we were able to show how different parts of the Himalaya deformed under different conditions at different times. We found that deformation preserved in the high temperature domains matched the predictions of the channel flow model, whilst deformation preserved in the lower temperature domains matched the predictions of duplex formation.

    We also saw evidence of lower temperature deformation overprinting higher temperature deformation. This led us to the understanding that as the mid-crustal rocks cooled, they strengthened and transformed from a weak crustal flow to a strong crustal block. Thus, the channel flow model was applicable to the early high temperature evolution of rocks at mid-crustal levels and duplex formation applied to the lower temperature evolution of rocks at upper-crustal levels. Importantly, the overprinting relationship between different types of deformation corresponds to changes in pressures and temperature felt by rocks from mid-crustal levels as they were uplifted to the surface.

    What are the implications for better understanding mountain forming processes in other regions?

    Despite its complexities, the Himalaya has a relatively simple geological history. As such, it provides a unique opportunity to determine the physical properties that control the formation of mountain belts and how these properties are interrelated. Such studies provide an invaluable modern day analogue for studying ancient, eroded, and now inactive mountain belts of which the geological record presents only a muddled and incomplete snapshot. Our study contributes to a growing understanding that the development of mountain belts is controlled primarily by its mechanical properties and that these properties change over space and time.

    What are the major unsolved or unresolved questions in this field and where are additional data or modeling efforts needed?

    Conceptual and numerical models are always an approximation of reality. Numerical models provide valuable insight into the boundary conditions that control tectonic process. In the broadest sense, such models have demonstrated that deformation of the lithosphere may be defined by a generalized mechanical stratigraphy typically corresponding to the upper and lower crust and lithospheric mantle. The ability of these models to reproduce observations reported from the geological record is testament to their validity and importance. Despite this, we know from geological observations that the mechanical properties of the lithosphere are highly variable and such variabilities have a first order control on the distribution of deformation from scales of microns to kilometers.

    Our study and others also demonstrate how mechanical properties of rocks change drastically over time and space as they are pushed and pulled through different parts of a mountain chain. Bringing the capabilities of numerical simulation of lithospheric deformation closer to reality is one of the key efforts needed in the field of tectonics. At the same time, it is vital that researchers studying the geological record understand the boundary conditions that govern tectonic processes and how changes in these boundary conditions are reflected in the rocks that lie before them.

    See the full article here .

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  • richardmitnick 8:06 am on May 5, 2017 Permalink | Reply
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    From Eos: “Integrating Research of the Sun-Earth System” 

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    2 May 2017
    Vania K. Jordanova
    Joseph E. Borovsky
    Valentin T. Jordanov

    1
    A rendering of the sunset from space. Attendees at a recent symposium convened to chart new courses in research about the reaction of the Earth system to the Sun and the solar wind. Credit: iStock.com/RomoloTavani

    Understanding the complex interactions between the magnetic fields of the Sun and Earth remains an important challenge to space physics research. Processes that occur near the Sun at tens of thousands of kilometers from the Earth can generate geomagnetic storms that affect the entire magnetosphere, down to the upper atmosphere.

    Solar eruption 2012 by NASA’s Solar Dynamic Observatory SDO

    NASA/SDO

    These storms also threaten the ever more sophisticated technologies that we place into the space environment to sustain us, for example, GPS, the satellites we rely on to monitor our weather, and relays that guide our radio transmissions. Increasingly, we need to develop space weather models that can provide timely and accurate predictions so that we can safeguard our society and the infrastructure we depend on.

    Against this backdrop, the third International Symposium on Recent Observations and Simulations of the Sun-Earth System (ISROSES-III) convened in Bulgaria last year to discuss recent advances and chart future developments in space weather research. ISROSES-III built upon the legacy of other similar conferences held in Bulgaria in 2002, 2006, and 2011.

    The main purpose of ISROSES-III was to foster interdisciplinary research and collaboration by enhancing communications between the space and Earth sciences communities worldwide. About 100 participants from around the world convened at the symposium to cover a broad range of topics.

    These topics included the fundamental physics of how waves and shocks in magnetic fields create dangerous radiation by accelerating particles throughout space. One study at the meeting examined the origin of these particles as measured from geosynchronous orbit.

    Another study analyzed the types of magnetic disturbances that lead to geomagnetic storms. Others focused on the structure of Earth’s magnetospheric current systems, improving our understanding of them and how they map to the ionosphere. Yet another detailed an improved representation of magnetospheric electric potential to create more accurate simulations.

    The main emphasis of the discussions was on integrating observations, theory, and numerical modeling across different temporal and spatial scales of the coupled Sun-Earth system.

    The community also highlighted common misconceptions as well as the need to develop contemporary and innovative technologies in space exploration (Figure 1). In the research community, it is easier to denounce new concepts than express doubt in old, deeply held misconceptions. In contrast, in the market economy, old concepts or misconceptions are constantly abandoned in search for something new. Symposium attendees discussed how the market economy has created new technologies that they should explore and that the research community needs to adopt the flexible mindset of corporations.

    1
    Fig. 1. Radiation measurement instrumentation versus consumer technology. (left) In the research community it is easier to denounce new concepts than express doubt in believed old misconceptions. (right) In the market economy, old concepts or misconceptions are constantly abandoned in search for something new. Attendees at a recent symposium on the Sun-Earth system stressed that new ideas brought into focus by the market economy shouldn’t be dismissed and that the research community should adopt the flexible mindset of corporations. Credit: Valentin T. Jordanov

    A special issue of the Journal of Atmospheric and Solar-Terrestrial Physics is currently being organized to publish papers related to topics discussed at ISROSES-III. Further information about the symposium is available on its official website [link is above].

    The main sponsors of the symposium were the Los Alamos National Laboratory Center for Space and Earth Science, the National Science Foundation, and the Scientific Committee on Solar-Terrestrial Physics’s Variability of the Sun and Its Terrestrial Impact (VarSITI) program. ISROSES-III also received collaboration and support locally from the University of Sofia, Bulgaria.

    —Vania K. Jordanova (email: vania@lanl.gov), Los Alamos National Laboratory, Los Alamos, N.M.; Joseph E. Borovsky, Space Science Institute, Boulder, Colo.; and Valentin T. Jordanov, Yantel LLC, Santa Fe, N.M.
    Citation: Jordanova, V. K., J. E. Borovsky, and V. T. Jordanov (2017), Integrating research of the Sun-Earth system, Eos, 98, https://doi.org/10.1029/2017EO072499. Published on 02 May 2017.

    See the full article here .

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  • richardmitnick 8:51 pm on May 1, 2017 Permalink | Reply
    Tags: Eos, KISS Project, Klyuchevskoy volcanic group (KVG), Understanding Kamchatka’s Extraordinary Volcano Cluster,   

    From Eos: “Understanding Kamchatka’s Extraordinary Volcano Cluster” 

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    An international seismological collaboration in Kamchatka, Russia, investigates the driving forces of one of the world’s largest, most active volcano clusters.

    1
    The Klyuchevskoy volcano in eastern Russia is shown here during an eruption that began in April 2016 and lasted about 6 months. Kamen and Bezymianny volcanoes are on the left. In 2015 and 2016, an international collaboration conducted the first geophysical survey of the broad region containing an especially active group of volcanoes, including Klyuchevskoy, on Russia’s Kamchatka Peninsula, near the Bering Sea. Credit: Benoit Taisne

    5.1.17
    Nikolai M. Shapiro, Christoph Sens-Schönfelder, Birger G. Lühr, Michael Weber, Ilyas Abkadyrov, Evegeny I. Gordeev, Ivan Koulakov, Andrey Jakovlev, Yulia A. Kugaenko, and Vadim A. Saltykov

    Soaring 4750 meters above the Kamchatka Peninsula near the western shore of the Bering Sea, the Klyuchevskoy volcano is one of the most active in the world. Many international flights connecting North America and Asia fly over the peninsula, where a group of active volcanoes, including Klyuchevskoy, occasionally fills the air with ash and dust. What drives the unusually high volcanic activity here? Do these volcanoes feed from the same large pool of magma?

    The Klyuchevskoy volcanic group (KVG), a part of the Kuril-Kamchatka volcanic belt, is located in a subduction zone where the Pacific oceanic plate plunges beneath the tectonic plate that carries the peninsula (Figure 1a). The strength and variety of volcanic activity in the region make it a natural laboratory to study where magma sits and how it moves in a subduction zone.

    2
    Fig. 1. KISS project setup. (a) Three-dimensional view of the Kamchatka-Aleutian tectonic plate junction. The red arrow indicates the location of the Klyuchevskoy volcanic group (KVG). The approximate positions of the active and extinct volcanic chains are indicated with red and blue dashed lines, respectively. (b) Region surrounding the KVG where the KISS seismic stations (green circles) were installed from July 2015 to July 2016. Broadband and short-period stations of the permanent seismic monitoring network are shown with black and white triangles, respectively. Red arrows show the locations of volcanoes that erupted during the past decade: (1) Klyuchevskoy, (2) Bezymianny, (3) Tolbachik, (4) Shiveluch, and (5) Kizimen.

    Previous surveys have been limited to the area around Klyuchevskoy. That changed in 2015–2016, when an international collaboration conducted the first geophysical survey of the entire KVG. The effort was named the Klyuchevskoy Investigation—Seismic Structure of an Extraordinary Volcanic System (KISS) experiment.

    ________________________________________________________________

    Instruments recorded the full sequence of events that preceded the most recent eruption of Klyuchevskoy last April.
    ________________________________________________________________

    Data from KISS’s instrument network offer an unprecedented look at one of Earth’s most active volcanic regions and could reveal whether the underlying magma reservoirs are connected by one large volcanic supercomplex. The instruments also provided a real-time record of an unfolding eruption: They recorded the full sequence of events that preceded the most recent eruption of Klyuchevskoy last April.

    The Klyuchevskoy Volcanic Group

    Over the past 10,000 years, the Klyuchevskoy volcano has produced an average of 1 cubic meter of erupted rocks every second [Fedotov et al., 1987]. This eruption rate is much higher than that of most volcanoes associated with subduction and is comparable to the growth of the Hawaiian volcanic chain, often considered one of the most vigorous volcanic systems of modern Earth.

    Besides Klyuchevskoy, the KVG contains 12 other large volcanoes. Two of them, Bezymianny and Tolbachik, have been very active in the past few decades. Two other active volcanoes, Shiveluch and Kizimen, are located only 60 kilometers north and south, respectively, of KVG (Figure 1b).

    A whole spectrum of eruptive styles is present in the KVG, ranging from steady Hawaiian-type eruptions, as seen during the two most recent eruptions of Tolbachik, to the strongly explosive eruptions of Bezymianny in 1956, which were among the world’s largest eruptions in the 20th century. (The name “Bezymianny” means “unnamed” in Russian: Until the 1956 eruption, the volcano was considered to be extinct, so no one bothered to give it a name.)

    The region’s exceptional volcanic activity is related to the unique tectonic setting of the KVG, located at the sharp corner between the Kuril-Kamchatka and Aleutian trenches. This corner is where the Hawaiian-Emperor seamount chain, the underwater mountain range that stretches down to Hawaii, is subducted, and the KVG is perched above the edge of the subducted slab (Figure 1a).

    Geodynamic models that attempt to explain the voluminous volcanism in the KVG are complex and include many factors. They include the release of fluids from the thick, highly hydrated Hawaiian-Emperor crust [Dorendorf et al., 2000], the mantle flow around the corner of the Pacific Plate [Yogodzinski et al., 2001], and the recent detachment of a portion of the slab due to a recent eastward jump of the subduction zone beneath Kamchatka [Levin et al., 2002]. The large variability of lavas and eruption styles reflects the complexity of the feeding system of magma sources and reservoirs in both the upper mantle and the crust.

    A Unique Natural Laboratory

    Because of its strong and variable activity, the KVG is a unique natural laboratory for studying volcanism in a subduction zone. Understanding how this zone functions requires detailed knowledge about the configuration of the subducted oceanic plates and about the distribution of magma conduits and reservoirs within the mantle wedge and the crust. A particularly important question is whether the individual KVG volcanoes are fed from independent magma sources or form a single interconnected magmatic supersystem.

    Gathering information about the deep KVG structure requires the use of geophysical methods. Past seismological studies [Koulakov et al., 2011] have revealed possible pathways of melts ascending from the subducting slab and a multilevel system of magma reservoirs in the crust. However, the structures that these studies illuminated are mainly restricted to a few tens of kilometers surrounding the Klyuchevskoy volcano, where most existing permanent seismic stations are located (Figure 1b). A full understanding of the behavior of the KVG magmatic system requires an investigation of subsurface structures at a much larger scale.

    3
    Fig. 2. KISS experiment fieldwork often took place in remote locations. (top left) Team members install an instrument station. The Ushkovsky, Klyuchevskoy, Kamen, and Bezymianny volcanoes are in the background. (top right) This typical installation configuration has a sensor on the left and a CUBE portable seismic digitizer (to capture and record ground motion) with Baken-VC1 batteries on the right. (bottom) A Kamaz truck and Robinson helicopter transport the equipment and field crews. Klyuchevskoy (erupting) and Kamen volcanoes are seen in the background.

    The KISS Project

    To undertake such a large-scale seismological investigation of the KVG, we formed a consortium of institutions from Russia, France, and Germany and designed the KISS experiment. We operated a temporary network of 83 seismographs between August 2015 and July 2016.

    The experiment took place in difficult terrain; helicopters and off-road trucks were needed to transport the equipment and field crews to the installation sites (Figure 2). An eruption-triggered mudflow destroyed one site, and a few others were wrecked by bears. Despite the harsh environment, the team recovered data from 77 instruments (Figure 1b).

    Initial inspection of seismograms indicates that the network successfully recorded many tectonic and volcanic earthquakes and volcanic tremors (Figure 3). The collected data set, combined with records from permanent seismic stations, will be used to study various types of earthquakes associated with the volcanic and magmatic activity and to image the crust and upper mantle with multiscale seismic tomography.

    4
    Fig. 3. Examples of seismic signals recorded by the KISS temporary stations (vertical component seismograms). (a) A tectonic M = 4.6 earthquake occurred near the Kamchatka-Aleutian junction on 29 September 2015. (b) Deep long-period earthquakes originated approximately from the crust-mantle transition depth from the region south of KVG on 29 September 2015. (c) Tremor emitted by Klyuchevskoy volcano on 15 March 2016.

    These results will help us understand why exceptionally large amounts of melts are generated in the upper mantle at the Kamchatka-Aleutian subduction corner and how these magmas are transformed during the ascent through the crust, producing the vigorous and very variable volcanism we see at the surface.

    Monitoring the KVG for Hazardous Eruptions

    Volcanic eruptions regularly affect a few small settlements located near the KVG, and they pose a significant threat to aviation because many international flights that connect North America and Asia pass over Kamchatka. Large explosive eruptions such as those of Bezymianny in 1956 and Shiveluch in 1964, when about 1 cubic kilometer of erupted material was ejected, might be particularly dangerous.

    Moreover, Kamchatka has a well-established record of even larger caldera-forming eruptions in the Holocene [Braitseva et al., 1995], with the largest of them forcibly ejecting about 150 cubic kilometers of rock fragments (tephra).

    5
    The Klyuchevskoy volcanic group in northeastern Russia, as seen from the International Space Station, viewed from the southeast. Credit: Earth Science and Remote Sensing Unit, NASA Johnson Space Center

    Considering that at present more than half of Kamchatka volcanic magmas are generated below the KVG, we cannot ignore the possibility of a future extreme explosive event in this region. We expect that the results of the KISS experiment will help us to evaluate such extreme event scenarios by improving our knowledge of the size of the KVG crustal magmatic reservoirs, along with the volume of potentially explosive magmas that they might contain.

    When the Klyuchevskoy volcano rumbled back to life and erupted in April 2016, the KISS network recorded the full sequence of reactivation leading up to the eruption. We will use this data set to improve our knowledge of how the rise of magma and the preeruptive buildup of pressure are expressed in the continuous seismic signals. The data will also help refine the routine monitoring of the KVG and other nearby volcanoes performed by the Kamchatka Branch of Russia’s Geophysical Survey and by the Kamchatka Volcanic Eruption Response Team, which is operated by the Institute of Volcanology and Seismology.

    Acknowledgments

    The KISS experiment was supported by the Russian Science Foundation (grant 14-47-00002), the French project “Labex UnivEarth,” and the Université Sorbonne Paris Cité project “VolcanoDynamics.” Sixty seismographs were provided by Geophysical Instrument Pool Potsdam (GIPP) from the Helmholtz Center Potsdam-GFZ German Research Centre for Geosciences, and 23 were provided by the partner institutions from the Russian Academy of Sciences: the Institute of Volcanology and Seismology, the Trofimuk Institute of Petroleum Geology and Geophysics, and the Kamchatka Branch of the Geophysical Survey. KISS data are stored in the GFZ Seismological Data Archive operated by the GEOFON program and will be openly available after a 3-year embargo period. We are grateful to Sergey Abramenkov, Benjamin Heit, Pavel Kuznetsov, Ekaterina Kukarina, Roman Kulakov, Alexey Kotlyarov, Valeriy Gladkov, Petr Voropaev, Dmitry Droznin, Sergey Senyukov, and Vitaly Bliznetsov, who participated in the fieldwork. Special thanks are owed to Sergey Chirkov for providing field photographs and to the truck driver, Igor Uteshev, as well as to the helicopter pilot, Gennady Kroshkin.

    Author Information

    Nikolai M. Shapiro (email: nshapiro@ipgp.fr), Institut de Physique du Globe de Paris, France; Christoph Sens-Schönfelder, Birger G. Lühr, and Michael Weber, GFZ German Research Centre for Geosciences, Potsdam, Germany; Ilyas Abkadyrov and Evegeny I. Gordeev, Institute of Volcanology and Seismology, Far East Branch of Russian Academy of Sciences, Petropavlovsk-Kamchatsky, Russia; Ivan Koulakov and Andrey Jakovlev, Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences and Novosibirsk State University, Novosibirsk, Russia; and Yulia A. Kugaenko and Vadim A. Saltykov, Kamchatka Branch of the Geophysical Survey, Russian Academy of Sciences, Petropavlovsk-Kamchatsky, Russia

    Citation: Shapiro, N. M., C. Sens-Schönfelder, B. G. Lühr, M. Weber, I. Abkadyrov, E. I. Gordeev, I. Koulakov, A. Jakovlev, Y. A. Kugaenko, and V. A. Saltykov (2017), Understanding Kamchatka’s extraordinary volcano cluster, Eos, 98, https://doi.org/10.1029/2017EO071351. Published on 01 May 2017.

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  • richardmitnick 7:51 am on April 25, 2017 Permalink | Reply
    Tags: , Eos, , Rock Avalanches   

    From Eos: “What Causes Rock Avalanches?” 

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    4.24.17
    Terri Cook

    1
    A giant rock avalanche preserved in the Nyainqentanglha Mountains of the Tibetan Plateau, China. Researchers use soil sampled from the avalanche to assess the mechanics behind the frictional weakening of the soil and its implications for the hypermobilty of rock avalanches. Credit: Yufeng Wang.

    Rock avalanches, sudden rock slope failures characterized by very rapid velocities, long runouts, and large volumes, pose some of the most dangerous and expensive geological hazards in mountainous regions. Although numerous mechanisms, including air pockets, fine powder along their base, and elevated pore fluid pressure, have been proposed to explain rock avalanches’ distinctive characteristics, the specific reasons for their “hypermobility” are still vigorously debated by scientists.

    To improve our understanding of what causes these disasters, Wang et al. conducted a series of laboratory tests to examine the weakening mechanisms that contributed to the high-speed motion of the Yigong rock avalanche on the Tibetan Plateau in 2000. This event dislodged 110 million cubic meters of material, which traveled more than 10 kilometers in 10 minutes before reaching and damming the Yigong River. Two months later, when the river finally broke through the avalanche debris, it unleashed a devastating flood that killed 94 people and destroyed the homes of more than 2 million citizens.

    Using a shear rotary apparatus, which rapidly rotates ring-shaped samples to simulate motion along a fault, the team varied the rate at which they applied shear stress to samples of soil obtained from the base of the Yigong rock avalanche and then analyzed each deformed sample’s features. The results indicate that elevated temperatures caused by frictional heating weakened the Yigong basal soil through the combined effects of two mechanisms: moisture fluidization, which both lubricates the sample and reduces the adhesion between its fine particles, and thermal pressurization, which causes friction-heated water to expand, further weakening the fault zone.

    Although the generation of nanoparticles from particle fragmentation may also facilitate soil weakening, this mechanism did not play a key role in generating the Yigong rock avalanche, the team reports. The results have implications for researchers in many geologic disciplines, including landslide dynamics, earthquake mechanics, and risk assessment. (Journal Geophysical Research: Solid Earth, https://doi.org/10.1002/2016JB013624, 2017)

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