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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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  • 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.

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    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 .

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  • richardmitnick 12:05 pm on May 8, 2017 Permalink | Reply
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    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.

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    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.

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    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.

    See the full article for references for this work.

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

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

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    18 April 2017
    Terri Cook

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

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

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

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

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

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

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

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  • richardmitnick 3:15 pm on April 11, 2017 Permalink | Reply
    Tags: , Earth's Wobbly Path Gives Clues to Its Core, Eos, , , Nutation, Precession   

    From Eos: “Earth’s Wobbly Path Gives Clues to Its Core” 

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    Understanding the Earth Core and Nutation; Brussels, Belgium, 19–21 September 2016

    4.11.17
    Veronique Dehant
    Richard Gross

    1
    The way that Earth precesses (large white cones) and nutates (red wavy line) in space gives clues to processes in its interior. At a recent workshop, scientists discussed the fluid, gravitational, and magnetic factors that cause these motions. The white circle indicates the ecliptic (the Sun’s apparent path across Earth’s surface), and the gold circle indicates Earth’s equator. Adapted from Dehant and Mathews (2015), Precession, Nutation, and Wobble of the Earth, 551 pp., Cambridge University Press, New York.

    The gravitational pull of the Sun and Moon on the Earth, as well as many other smaller geophysical effects (including motions of Earth’s fluid core), cause Earth to wobble. Earth is not a perfect sphere but an ellipsoid flattened at its poles, so the forces acting upon Earth alter both its speed of rotation and the orientation of the axis on which it spins. The term “precession” describes the long-term trend of this latter motion, which is roughly circular and analogous to the motion of a spinning top. “Nutation” is the name given to shorter-term periodic variations: wobbles along this circular track.

    Last September, scientists gathered for a workshop in Brussels, Belgium, to discuss the role of Earth’s core in its nutation and to gain further insight into Earth’s interior processes. This was the first such workshop to be held within the framework of the newly established RotaNut project in the frame of an ERC (European Research Council) Advanced Grant.

    Precession causes the rotation axis of Earth to move in space at about 1.5 kilometers each year. Nutation introduces periodic variations on the order of 600 meters back and forth around the precession circle (from a vantage point looking down on the planet’s pole). Present observations allow these motions to be measured at the centimeter level. Speakers noted how such observations show that there are significant differences on the order of a few centimeters (1 milliarc second, or about 3 centimeters) between observations and the standard theoretical model of precession and nutation. The theoretical model was adopted by the International Astronomical Union in 2000 and by the International Union of Geodesy and Geophysics in 2003.

    2
    As Earth rotates on its axis, it precesses like a wobbly spinning top, but it also nutates, or wobbles along the circular precession path. This illustration shows Earth’s precession and nutation, as well as the orbital paths of a Galileo satellite constellation. Adapted from J. Huart, European Space Agency

    The theoretical model is based on the idea that Earth reacts as a deformable object with a deformable inner core, a fluid outer core, a deformable mantle that is both viscous and elastic (it can flow and stretch), an atmosphere, and oceans. But the theoretical model is not perfect, attendees discussed. In particular, scientists still don’t understand the interactions between the inner core, fluid outer core, and mantle well enough to properly model them.

    Because the core transfers angular momentum to the mantle, interactions between the two regions play an important role in nutation modeling, meeting participants agreed. The current nutation model incorporates the effect of the flattening of the core due to Earth’s rotation and the fluid pressure and gravitational effects on that flattened boundary, as well as the effects of a simple uniform, dipolar magnetic field.

    Today, we understand that there are important contributions from other components of the magnetic field and possibly other effects, like the viscosity of the inner core, the viscosity of the outer core, and core stratification. In addition, the core-mantle boundary is not smooth, and pressure forces acting on these topographical features could also play an important role.

    The workshop shed light on all of the mechanisms that might be influencing Earth’s nutation, including the possible interaction between rotational modes and inertial modes inside the liquid core. Future meetings will highlight outcomes and new insights that emerge from the discussions held during this meeting.

    The work of Veronique Dehant was performed at the Royal Observatory of Belgium under funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program (advanced grant agreement 670874). The work of Richard Gross was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

    —Veronique Dehant, Royal Observatory of Belgium, Brussels; and Richard Gross (email: richard.gross@jpl.nasa.gov), Jet Propulsion Laboratory, California Institute of Technology, Pasadena

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  • richardmitnick 9:26 am on April 4, 2017 Permalink | Reply
    Tags: , , Eos, Why Do Great Earthquakes Follow Other at Subduction Zones?   

    From Eos: “Why Do Great Earthquakes Follow Other at Subduction Zones? “ 

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    31 March 2017
    Terri Cook

    A decade of continuous GPS measurements in South America indicates that enhanced strain accumulation following a great earthquake can initiate failure along adjacent fault segments.

    1
    People walk through the streets of Talca, Chile, past major damage from the earthquake on 12 March 2010. Credit: Joe Raedle/Getty Images

    Recently, seismologists have recognized that great subduction zone earthquakes, also known as megathrust earthquakes, tend to recur in “supercycles.” These cycles are characterized by the release of strain in a cluster of earthquakes within a few years of each other, followed by a lengthy period of quiescence ranging from several decades to several centuries, during which strain once again accumulates. Megathrust earthquakes have the potential to cause widespread damage and devastating tsunamis, yet the mechanisms that trigger two or more of these events within a few years to a decade are still not well understood, primarily because of a lack of long-term geodetic data.

    Now Melnick et al. [Geophysical Research Letters] have analyzed a decade’s worth of continuously measured GPS data spanning two great earthquakes, the 2010 Maule (M 8.8) and 2015 Illapel (M 8.3) events.

    3
    2010 Maule (M 8.8)

    6
    2015 Illapel (M 8.3)

    Both earthquakes occurred along the central Chilean margin where the Nazca plate is diving beneath the South American plate at a rate of 66 millimeters per year. The team used these data to estimate changes in surface deformation rates throughout the Andes Mountains and then compared the results with numerical simulations.

    The researchers’ findings indicate that surface velocities increased following the Maule earthquake, a change they attribute to the large-scale, elastic response of both the continental and oceanic plates to fault slip during and immediately after the earthquake. This response, the team argues, accelerated the rate of shortening across the megathrust and heightened the stress on adjacent fault segments. According to the researchers, the resulting period of stress accumulation constitutes a “superinterseismic” phase of the earthquake cycle that may have brought nearby fault segments closer to failure and ultimately triggered the 2015 event.

    This study demonstrates that cycles of megathrust earthquakes can be strongly influenced by the behavior of nearby seismic events. The results may help clarify the occurrence of clusters of other great earthquakes, including those that have occurred in Alaska, Cascadia, Sumatra, and Japan, as well as provide insight into the processes controlling the lag time between those events.

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  • richardmitnick 11:53 am on March 23, 2017 Permalink | Reply
    Tags: , , Eos, Neotectonics   

    From Eos: “Neotectonics and Earthquake Forecasting” 

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    3.23.17
    Ibrahim Çemen
    Yücel Yilmaz

    The editors of a new book describe the evolution of major earthquake producing fault zones in the eastern Mediterranean region and explore how earthquake forecasting could improve.

    1
    Digital elevation map of the Eastern Mediterranean region showing major neotectonics structural features, volcanic centers, and epicenters of the earthquakes since 1950. Credit: Çemen and Yilmaz, 2017

    A research symposium on “Neotectonics and Earthquake Potential of the Eastern Mediterranean Region” at the AGU Fall Meeting in 2013 drew researchers from around the world. A new book arising from that symposium has just been published by the American Geophysical Union. The symposium organizers and book editors, Ibrahim Çemen and Yücel Yilmaz, answers some questions about the book and the relevance of research in this field.

    What is neotectonics and why is it important?

    Neotectonics is a branch of Earth Sciences that studies the present-day motions of the Earth’s tectonics plates. When these motions reach a certain level they cause sudden ground shaking, i.e. earthquakes. Neotectonics studies are important to provide evidence for locations of major earthquakes along active fault zones of the world, such as the San Andreas in California, USA. Therefore, neotectonics and earthquake prediction are intimately associated subjects, important for scientists and the people living in areas where earthquakes have occurred in the past and likely to occur in the future.

    What different methods are used in the study of neotectonics?

    Neotectonics studies draw data from range of geological and geophysical methods, including GPS studies, geodesy, and passive source seismology. They also combine data from different sources including field work, seismic, experimental, computer-based, and theoretical studies. In addition, morphotectonic studies are extensively used in neotectonics. Morphotectonics focusses on landforms and involves combining geological and morphological data to evaluate how the Earth’s crust is currently being deformed and therefore modifying the land surface.

    Why the focus on the eastern Mediterranean region?

    The region is one of the most seismically-active areas of the world and has experienced many devastating earthquakes throughout history. Furthermore, many large earthquakes are expected to occur during the twenty-first century and beyond, creating a societal need for research on neotectonics and earthquake potential. Moreover, the findings specific to the eastern Mediterranean are relevant to other seismically-active regions of the earth including the western Mediterranean, western North America (including California), central and western South America, and central and southeastern Asia.

    With evolution of geophysical methods and techniques, is there hope for improving earthquake forecasting capabilities over time?

    Crustal movements along major fault zones lead to occurrence of earthquakes. New geophysical methods and techniques are being developed to monitor these movements. Eventually, earthquake scientists will be able to identify the tipping points related to these movements along the faults before an earthquake occurs. These tipping points include the build-up of stress and amount of displacements along the faults over the years (usually decades). Once these tipping points are identified, scientists will be able to more accurately forecast when an earthquake will occur along a given fault, within a certain period of time. These forecasts may be given with a percentage of chance, similar to weather forecasting.

    What kind of future research may be necessary to address some of the remaining questions in this field?

    There are still many important questions to be answered relating to neotectonics and earthquakes including: How did the major earthquake producing fault zones evolve in recent geologic time? What are the depths of these fault zones in the Earth’s crust? What is the state of stress along the zones? New insights to these questions can be provided if detailed crustal geometry of the major earthquake producing faults can be imaged precisely by combining modern geophysical techniques such as seismic tomography and 3D gravity modelling.

    Active Global Seismology: Neotectonics and Earthquake Potential of the Eastern Mediterranean Region, 2017, 306 pp., ISBN: 978-1-118-94498-1, list price $199.95 (hardcover)

    See the full article here .

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