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  • richardmitnick 1:57 pm on September 12, 2017 Permalink | Reply
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    From Eos: “Revising an Innovative Way to Study Cascadia Megaquakes” 

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    9.12.17
    Sarah Witman

    Researchers probe natural environments near subduction zones to decrypt underlying mechanisms of major earthquakes.

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    FEMA

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    A diagram of the Cascadia Subduction Zone provided by the Oregon Historical Society.

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    The Cascadia subduction zone is likely to experience a megathrust earthquake in the next 50 years or so, but a revised technique uses heat data to better understand the physical nature of subduction zones. Credit: NASA/ISS

    Along the west coast of North America, the Cascadia subduction zone stretches more than 1,000 kilometers from Vancouver Island to Cape Mendocino, Calif. It produced a magnitude 9 megathrust earthquake about 300 years ago, one of the biggest quakes in world history.

    Scientists know that Cascadia will produce another earthquake at some point in the future; the question is how soon. The odds of it happening in the next 50 years are 1 in 3. The Federal Emergency Management Agency projects that Cascadia’s next megathrust earthquake will cause thousands of deaths and injuries and leave millions in need of shelter, food, and water.

    To better understand subduction zones, scientists often study the thermal environments of material that has been pushed up onto the surface during past earthquakes. This buildup of material, called an accretionary wedge, might consist of rock, soil, sand, shells, or any other kind of debris. These wedges also sport subtly different average temperatures at various depths, compared to material located off the wedge.

    In a recent study, Salmi et al. [Journal of Geophysical Research] examined the thermal environment of the Cascadia subduction zone’s accretionary wedge, which stretches for about 97 kilometers along the coast of the state of Washington. Their goal was to find out more about the physical changes of fluids and solids within the wedge in the hopes that the knowledge can help them better anticipate future earthquakes.

    Using data collected on a cruise by the R/V Marcus G. Langseth, the researchers found significant variations in temperature within this section of the Cascadia subduction zone, as well as signs of gas hydrates (ice-like deposits that form from natural gas at the bottom of the ocean) throughout the region. They also detected that most fluids from the deep move upward through the accretionary wedge instead of through the crust, which is different than in most other subduction zones. This change in fluid pathway prevents the plate from cooling and reduces the area where an earthquake might rupture along the two plates: completely within the accretionary wedge, rather than under the continental plate.

    This is the first study to concentrate on the southern Washington margin alone, rather than the subduction zone as a whole, revealing the influence of fluid distribution on local, small-scale temperature variability. This insight opens the door to further research into how local temperature variability might interact with other factors, like stress or fault roughness, to affect earthquake hazards. Overall, this study provides a revised method for probing the thermal environment of an accretionary wedge, a crucial link to the cause of ruptures in Earth’s crust that can lead to earthquakes and tsunamis.

    By understanding these mechanisms more fully, scientists can tell us more about how to prepare for the smallest of tremors and the largest of megaquakes. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1002/2016JB013839, 2017)

    See the full article here .

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  • richardmitnick 3:06 pm on September 8, 2017 Permalink | Reply
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    From Eos: “Largest Flare of Past 9 Years Erupts from Sun” 

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    9.8.17
    Kimberly M. S. Cartier

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    NASA’s Solar Dynamics Observatory captured this image, blended from two ultraviolet filters, of (left) the X9.3 class solar flare that erupted from the Sun on 6 September and (right) a simultaneous smaller flare from a different active region. Credit: NASA/Goddard Space Flight Center/Solar Dynamics Observatory

    NASA/SDO

    A flare erupting from the surface of the Sun on Wednesday blocked communications and interfered with navigational frequencies across the globe. Large portions Europe, Africa, Asia, and Australia experienced disruptions to low-frequency radio communications, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).

    As the flare jetted outward from the Sun’s surface, the star’s outer atmosphere, or corona, belched a huge cloud of ultrahot, electrically charged particles, known as a coronal mass ejection (CME) toward Earth. The CME prompted a warning from NOAA solar storm watchers of an impending strong (G3) geomagnetic storm or greater through today. An updated NOAA report at 1:57 p.m. Coordinated Universal Time (UTC) today revised the agency’s assessment to “G4 (Severe) geomagnetic storm levels” for the day-lit side of Earth.

    In addition to roiling communications and navigation signals, such geomagnetic storms can create surges or shutdowns in power grids and produce brilliant auroras visible at lower latitudes than usual.

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    Two solar flares exploded from the same region of the Sun within a few hours of each other. This time-lapse footage of the region, seen here in extreme-ultraviolet wavelengths, shows flares and CMEs many times larger than Earth. Credit: NASA/Goddard Space Flight Center/SDO

    According to NOAA’s Space Weather Prediction Center, the flare sprung from the Sun at 12:02 p.m. UTC on 6 September, accompanied by the CME, which arrived at Earth late last night and is expected to persist through today.

    A Blast amid the Calm

    NOAA heliophysicists identified Wednesday’s flare as the largest solar flare to date in the current solar cycle, which is an approximately 11-year cycle that tracks when solar activity increases and decreases. The current solar cycle began in December 2011. Although the Sun’s activity is declining on average, large flares such as these are not uncommon during this stage of the cycle.

    “Some of the strongest solar events occur near solar minimum,” Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate, explained on Twitter. “Space Weather matters during the entire solar cycle!”

    Heliophysicists associated with NASA’s Solar Dynamics Observatory (SDO) classified this event as an X9.3 solar flare, meaning it’s in the most intense class of flares. What’s more, the same region of the Sun had produced another X-class flare about 3 hours earlier on the morning of 6 September. Three other moderate-intensity flares have exploded from the region since 4 September, in addition to flares from other active areas on the Sun’s surface.

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    The Sun produced five strong solar flares from 4 to 7 September, including the X9.3 event that generated the large CME near time mark “2017/09/06 14:00.” CMEs are best observed when the bright disk of the Sun is blocked by a coronagraph, as seen in this sequence of images taken by the Large Angle and Spectrometric Coronagraph (LASCO) instrument on the NASA/ESA Solar and Heliospheric Observatory (SOHO). Credit: SOHO/LASCO/National Research Laboratory team

    “It’s the active region that keeps on giving!” tweeted Sophie Murray, a space weather scientist at Trinity College in Dublin, Ireland.

    NOAA’s Space Weather Prediction Center also reported a strong (R3) radio blackout on Wednesday at 9:10 a.m. UTC due to both flares that day.

    See the full article here .

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  • richardmitnick 1:45 pm on September 5, 2017 Permalink | Reply
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    From Eos: “New Findings from Old Data” 

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    29 August 2017
    Mike Liemohn

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    One of more than 33,000 pictures of Jupiter and its five major satellites taken by two Voyager spacecraft in 1979. Credit: NASA

    We are approaching the 40-year anniversary of the two Voyager spacecraft making their 1979 flybys of the planet Jupiter. Jupiter’s magnetosphere is big. The satellites were moving fast, and each one only spent a few days passing through the magnetic bubble around this planet so two flybys does not seem like much of an opportunity to gather data. But the plasma science instruments on the spacecraft were high quality sensors that led to numerous papers on the magnetospheric structure, dynamics, composition, and dominant physical processes.

    Long after the Voyager observations the Galileo spacecraft orbited Jupiter for 8 years in the 1990s and 2000s, providing a rich set of magnetospheric measurements for nearly a solar cycle.

    NASA/Voyager 1

    The Voyager flybys, however, offer comparative and complementary measurements from a different solar cycle and are still proving themselves to be useful.

    Several of those initial studies were authored by Fran Bagenal, now a professor at the University of Colorado in Boulder.

    In the decades since, she has never lost her love of Jupiter’s magnetosphere and her publication list is full of papers on the topic.

    In fact, this summer Bagenal and coworkers (primarily two undergraduate students) have a three-paper series just published in JGR Space Physics on the recalibration and reanalysis of the Voyager data.

    In the first one [Bagenal et al., 2017 (Journal of Geophysical Research)], the ion composition data from the Plasma Science Instrument (PSI) onboard Voyager 1 and 2 were reprocessed with the help of modern physical chemistry models to “constrain the composition and reduce the number of free parameters.”

    In the second article, led by student Logan Dougherty [Dougherty et al., 2017 (Journal of Geophysical Research)], they focus on the main constituents, specifically oxygen and sulfur ions, including a detailed examination of their charge states and flow speeds as a function of radial distance from the planet.

    In the third paper, led by student Kaleb Bodisch [Bodisch et al., 2017 (Journal of Geophysical Research) ], the focus shifts to the minor ions, including protons, which are less than 20 per cent of the particles in the Jovian magnetosphere, as well as sodium and sulfur dioxide ions, which have even smaller abundances.

    Throughout the series, the researchers develop a robust 2-D model of the Jovian plasma sheet. They provide several key points of new understanding of Jupiter’s space environment that could be highly valuable for comparative planetary investigations. In addition, this work is particularly important with Juno currently orbiting Jupiter and two other missions, the European-led Jupiter Icy Moons Explorer and NASA’s Europa Clipper, in development.

    In our field, emphasis is often put on the spectacular and first-look and ground-breaking observations, like Voyager’s continued outward journey into interstellar space. We often do not celebrate and recognize the fundamental yet longer-term work of producing high quality measurements with documentation and access to the wider community.

    Fran and her co-workers have pulled this data from the deep reaches of the Planetary Data System (NASA’s repository for planetary mission observations), updated old codes written in the 1970s, and, perhaps, best of all, made their new data set available online. They have not only gleaned new insight from archival data but also made this old data accessible for the current generation of researchers.

    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 3:06 pm on September 1, 2017 Permalink | Reply
    Tags: A Grand Tour of the Ocean Basins, , Eos,   

    From Eos: “A Grand Tour of the Ocean Basins” 

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    9/1/17
    Declan G. De Paor

    A new teaching resource facilitates plate tectonic studies using a Google Earth virtual guided tour of ocean basins around the world.

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    Google Earth images provide detailed views of Earth’s continents and oceans. Custom overlays enhance the images, turning them into resources for instructors and students studying plate tectonic theory and other topics. A new online teaching resource takes advantage of Google Earth to offer a virtual tour of the world’s ocean basins, providing insights into the processes that shape oceans and continents. This Google Earth image displays data overlays showing ages of the ocean floor, together with tectonic plate boundaries. Credit: Models: Age of the Lithosphere for Google Earth and Using Google Earth to Explore Plate Tectonics. All figures showing Google Earth are ©2017, Google Inc. Images: PGC/NASA, Landsat/Copernicus, USGS. Data: SIO, NOAA, U.S. Navy, NGA, GEBC, USGS.

    Students, especially those at the beginner levels, are often presented with simplistic visualizations of plate tectonics that lack the rich detail and recent science available to researchers. Yet plate tectonics’ ability to explain fine details of the continental and oceanic lithosphere is the strongest available verification of this theory. Presenting more of this detail in a real-world setting can help motivate students to study the processes that mold Earth’s oceans and continents.

    Google Earth allows instructors and students to explore Earth’s oceans and continents in considerable detail. The images in this open access, online resource provide a striking portrait of the planet’s continents and oceans. A user can browse this virtual globe’s features and explore in fine detail mountain ranges, geological faults, ocean basins, and much more.

    Properly annotated, Google Earth can also provide insights into the geophysical processes that created the world as we see it today. It can serve as an informative tool for students and instructors in their study of tectonic plates, bringing to life the geological significance of features such as the famous Ring of Fire that girdles the Pacific.

    Our project, Google Earth for Onsite and Distance Education (GEODE), has now added a Grand Tour of the Ocean Basins to its website to provide such help. This tour gives instructors a way to become familiar with details of Earth’s tectonic story and to stay up to date about new insights into tectonic processes. They can then better respond to, and provide context for, on-the-spot questions from students as they become caught up in the images they view on Google Earth.

    The tour was designed for geoscience majors, but an instructor could edit it to suit general education or high school courses. Students can use the documentation as a self-study tool, even if they do not have extensive prior knowledge of tectonic processes.

    A Teaching Sequence

    The tour is organized in a teaching sequence, beginning with the East African Rift, continuing through the Red Sea and Gulf of Aden into the Arabian Sea. The tour proceeds to the passive margins of Antarctica, which lead tourists to the South Atlantic, North Atlantic, and Arctic oceans. En route, students visit thinned continental shelves and abandoned ocean basins (where seafloor spreading no longer occurs). The Lesser Antilles Arc and Scotia Arc serve as an introduction to Pacific continental arcs, transform boundaries, island arcs, and marginal basins. The tour ends with ophiolites—slivers of ocean thrust onto land—in Oman.

    The tour uses a series of Google Earth placemarks (map pin icons), with descriptions and illustrations in a separate Portable Document Format (PDF) file. We provide plate tectonic context by combining two superlative resources: ocean floor ages from the Age of the Lithosphere for Google Earth website (based on Müller et al. [2008]) and the plate boundary model from Laurel Goodell’s Science Education Resource Center page (based on Bird [2003]).

    Not Your Grandmother’s Plate Tectonics

    Our virtual tour of ocean basins includes lots of up-to-date local details, thanks largely to recent research that takes advantage of precise data provided by satellite-based GPS. Just as your car’s GPS receiver tells you how fast you are traveling and in what direction, highly sensitive GPS devices record plate velocities, even though plates move only at about the rate your fingernails grow. Researchers no longer regard plates as absolutely rigid: Internal plate deformation was first documented in the Indian Ocean [Wiens et al., 1985].

    GPS surveys and seismic records reveal large regions of deformation along diffuse boundaries between tectonic plates, where the movement is not along one well-defined plane. Instead, movement involves microplates: relatively rigid parts of plates that move with significantly differing velocities. For example, tour stop 9, the eastern Indian Ocean, shows the presence of widespread diffuse deformation in the Indian, Australian, and Capricorn plates (Figure 1). For mechanical reasons, these microplates tend to pivot about points separating regions of diffuse extension from compression, represented by white circle icons in the Google Earth tour.

    Beyond Atlantic Style and Pacific Style

    Our Google Earth tour also allows us to address misconceptions about the boundaries between tectonic plates and between oceans and continents. Some of the most persistent misconceptions concern the differences between active plate boundaries and passive continental margins.

    A bit of background first: Active plate boundaries can be divergent (mid-ocean ridges), convergent (subduction and collision zones), or transform (e.g., the San Andreas Fault). At passive continental margins, oceanic lithosphere and continental lithosphere are welded together along the fossilized line of initial continental rifting. A person in our Google Earth tour will encounter numerous examples of both active plate boundaries and passive continental margins.

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    Fig. 1. This image from the grand tour illustrates diffuse deformation on the Indian, Australian, and Capricorn plates. Areas of extension are shaded gray; areas of contraction are yellow. Thick dashed lines mark the median lines of the zones of diffuse deformation. They define a diffuse triple junction. Open circles are poles of relative rotation of pairs of plates (a third pole may already be subducted under the Sunda Plate). These poles occupy regions of little deformation between the extensional and contractional zones. Purple dotted lines outline continental shelves. Credit: Based on data from Royer and Gordon [1997]

    Misconceptions arise from the introductory level on, where teachers present students with two basic cross sections of ocean basins: Atlantic style with two passive continental margins and Pacific style with two active plate boundaries. Students commonly draw cross sections with two symmetrical active convergent plate boundaries even though there is no such ocean basin on Earth.

    Symmetrical passive margins do exist, however: They border large regions of oceanic crust, including, for example, the North and South Atlantic oceans, the western portion of the Indian Ocean within the Arabian Sea, and the Southern Ocean between Australia and Antarctica as well as between Africa and Antarctica. But active basins are always asymmetrical, with ridges often far from the middle of the ocean basin. Seafloor spreading is generally symmetrical about ocean ridges (except for local instances of ridge jump), but there is no reason for subduction to occur at the same rate on either side of an ocean basin; hence, ridges migrate as they spread, and in places, they reach a trench and are subducted.

    Our grand tour presents lithospheric cross sections of the Pacific crust to scale, with its eastern 4,000-kilometer-wide Nazca Plate and western 12,000-kilometer-wide Pacific Plate. It also highlights the eastern Indian Ocean, with its passive margin against Madagascar and active plate boundary against Burma-Sumatra, the scene of the devastating, tsunami-generating earthquake of 26 December 2004 (Figure 2).

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    Fig. 2. An ocean can be bounded by a passive continental margin on one side and an active plate boundary on the other. In such cases, the spreading ridge is never in the middle of the ocean. A traverse from Madagascar in the west to Sumatra in the east serves as a modern-day analogue for times during the evolution of the Iapetus Ocean that was consumed in the Appalachian-Caledonian Orogeny.

    This combination of passive continental margin and active plate boundary serves as a good modern analogue for the Iapetus Ocean, the ocean that separated paleo–North America from paleo-Europe and paleo-Africa before the collisions that created the Appalachians, Caledonides, and associated mountains. Models of those mountain-building events involve a collision of active and passive sides of the ocean basin at times as Iapetus was consumed.

    Sampling Diversity in Ocean Basins

    The grand tour also visits many of the diverse features of Earth’s ocean basins. A significant amount of oceanic crust resides in failed or abandoned basins bounded by passive margins. Such regions include the Gulf of Mexico, the Labrador Sea and Baffin Bay between Canada and Greenland, the Bay of Biscay between France and Spain, the western Mediterranean, and the Tasman and Coral seas east of Australia, all of which are visited on the tour.

    Many offshore regions are underlain by oceanic crust that developed in marginal basins behind island arcs such as Japan and the Mariana Islands, and the tour visits these regions as well. Because the west side of the Pacific’s oceanic crust is so much older than the east, it is colder and denser and subducts steeply and rapidly. Consequently, trenches marking the initiation of subduction roll back eastward, like a Michael Jackson moonwalk. The resultant “trench suction” forces open multiple back-arc basins to the west of the main Pacific basin, with their own miniature spreading ridges.

    A third type of minor ocean basin is created by side-stepping transform fault arrays as in the Gulf of California and on the northern border of the Caribbean Plate. In such locations, transform faults are long, and spreading ridge segments are short.

    Finally, there are numerous oceanic plateaus with relatively thick crust derived from large igneous provinces or small submerged continental fragments. Examples of all of the above are included in our tour.

    Triple Junctions and Hot Spots

    The tour makes stops at triple junctions, where three major plates meet. At some locations, triangular microplates without any bounding continental margins grow, as exemplified by the Galápagos Microplate (Figure 3, tour stop 38). Researchers have found strong evidence that one such paleomicroplate grew to become the Pacific Plate (Figure 4) [Boschman and van Hinsbergen, 2016]. The Pacific oceanic crust never had passive continental margins. It was born at sea!

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    Fig. 3. Stop 38 on the Grand Tour of the Ocean Basins focuses on the Galápagos Microplate (designated µ in the image) on the East Pacific Rise. It sits at a triple junction where three large plates meet. The Galápagos hot spot to the east was probably instrumental in the location of the triple junction. Credit: Based on data from Schouten et al. [2008]

    Oceans are also home to mantle hot spot trails unrelated to plate boundaries. The grand tour visits the well-known Hawaiian Islands–Emperor Seamount trail. Numerous other trails are easily recognizable in Google Earth.

    File Formats and System Requirements

    The tour is presented in two file formats: Keyhole Markup Language (KML)—the format of Google Earth custom content—and an associated PDF file. Google Earth puts descriptive text and imagery into placemark balloons, which can obscure the surface of the map. Because these balloons cannot be dragged to one side, simultaneous viewing of KML maps and PDF descriptive documents is the solution. Dual monitors, twin projectors, or pairs of laptops make for the best viewing for personal study, lecture presentation, and student collaboration.

    The PDF document is laid out in frames suited to reading on digital devices. Each frame contains a block of text and associated imagery. Instructors may omit or rearrange tour stops to suit the needs of their courses. Because KML is human-readable, such rearrangements can be done in a text editor. Note that the KML file must be viewed on a desktop or laptop computer (Mac, Windows, or Linux) because Google Earth for mobile devices is highly limited.

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    Fig. 4. Stop 39 on the Grand Tour of the Ocean Basins looks at the formation of the Pacific Plate. The oldest isochrons are not seen at the western subduction zone with the Eurasian Plate and associated marginal basins; rather, the oldest oceanic crust forms a Russian doll–style set of nested triangles, suggesting that the Pacific Plate started as a triangular microplate growing from a triple junction, just like the Galápagos Plate today.

    Trying It Out for Yourself

    The KML and PDF files are available for download. The KML download contains a simple network link to an online KML document so that updates occur automatically whenever the document is opened in Google Earth.

    The author invites suggestions for continuously improving this resource.

    Acknowledgments

    Development was supported by the National Science Foundation under grant NSF DUE 1323419, “Google Earth for Onsite and Distance Education (GEODE).” Any opinions, findings, and conclusions or recommendations are those of the author and do not necessarily reflect the views of the National Science Foundation. Thanks are owed to the Eos editors and to two anonymous reviewers for very helpful suggestions that improved the submitted manuscript.

    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 1:16 pm on August 29, 2017 Permalink | Reply
    Tags: , Eos, Giovanni: The Bridge Between Data and Science   

    From Eos: “Giovanni: The Bridge Between Data and Science” 

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    24 August 2017
    Zhong Liu
    James Acker

    Using satellite remote sensing data sets can be a daunting task. Giovanni, a Web-based tool, facilitates access, visualization, and exploration for many of NASA’s Earth science data sets.

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    This time-averaged satellite map of the March aerosol optical thickness off the coast of western Africa from 2003 to 2016 incorporates several of the new capabilities of NASA’s Giovanni data visualization infrastructure. Credit: Giovanni

    Since the satellite era began, researchers and others have used data collected from Earth-observing satellites, but using satellite-based data sets remains challenging. Putting data into a common format, handling large volumes of data, choosing the right analysis software, and interpreting the results require a significant investment in computer resources, labor, and training.

    A new infrastructure system has been designed to assist a wide range of users around the world with data access and evaluation, as well as with scientific exploration and discovery. This system, the Geospatial Interactive Online Visualization and Analysis Infrastructure (Giovanni), was developed by the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC).

    The paramount goal of Giovanni is to provide scientists and the public with a simplified way to access, evaluate, and explore NASA satellite data sets. Here we describe the latest capabilities of Giovanni with examples, and we discuss potential future plans for this innovative system.

    Challenges of Using Satellite Data

    Over Earth’s vast oceans and remote continents, traditional large-scale, ground-based programs to observe the atmosphere, ocean, and land surface can be difficult and costly to deploy and maintain and are therefore impractical for providing adequate long-term observational data for research and applications. However, the need for large-scale observations is increasing as global observations become substantially more important for understanding global change processes like temperature and precipitation shifts.

    Satellite instruments can overcome surface observation limitations by making repeated, synoptic observations of the Earth’s land surface, ocean, and atmosphere. For example, NASA’s Earth Observing System (EOS) project is a global observation campaign consisting of a coordinated series of polar-orbiting satellites intended for long-term global observations, enabling improved understanding of Earth’s geophysical systems.

    However, many researchers find it challenging to access and use NASA data. Heterogeneous data formats, complex data structures, large-volume data storage, special programming requirements, diverse analytical software options, and other factors often require a significant investment in time and resources, especially for novices.

    By facilitating data access and evaluation, as well as promoting open access to create a level playing field for nonfunded scientists, NASA data can be more readily used for scientific discovery and societal benefits. Giovanni was developed to advance this goal. With Giovanni’s assistance, researchers around the world have published more than 1,300 peer-reviewed papers in a wide range of Earth science disciplines and other areas.

    A Brief History of Giovanni

    Giovanni was initiated and developed for faster and easier access to and evaluation of data sets at GES DISC [Liu et al., 2007; Acker and Leptoukh, 2007; Berrick et al., 2009]. The first implementation of Giovanni was an online visualization and analysis system for tropical rainfall data sets from NASA’s Tropical Rainfall Measuring Mission (TRMM).

    As the project gained popularity, scientists requested that more satellite data sets be included in Giovanni. To address this demand, we created multiple discipline- or mission-based data portals. The current Giovanni has evolved further, featuring a new unified Web interface to support interdisciplinary Earth system research, allowing synergistic use of data sets from different satellite missions.

    A Wide Selection of Data Sets

    Giovanni provides access to numerous satellite data sets, concentrated primarily in the areas of atmospheric composition, atmospheric dynamics, global precipitation, hydrology, and solar irradiance.

    More than 1,600 variables are currently available in Giovanni. The Web interface has keyword and faceted search capabilities for locating variables of interest (Figure 1). For example, a search for “precipitation” returns more than 100 related variables. A user performing a faceted search can filter for variables based on satellite missions (TRMM, Global Precipitation Measurement (GPM)), instruments, spatial or temporal resolution, or other categories.

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    Fig. 1. More than 1,600 variables are available for visualization and analysis in the Giovanni Web interface, shown here. Users have access to commonly used analytical methods and visualization, various search capabilities, and file formats that support GIS data exploration. Input and output data can be downloaded for further analysis. Credit: Giovanni

    The operating lifetimes of low-Earth-orbiting satellites are often quite limited (on the order of 5 years), far less than the 30 years recommended by the World Meteorological Organization for developing climatology data sets. Some users, however, may still wish to conduct preliminary studies with these satellite data sets to obtain information on spatial distribution and interseasonal variation. Giovanni provides the capability to derive climatological maps and time series based on user-defined time periods (see Figure 2).

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    Fig. 2. The TRMM Multisatellite Precipitation Analysis (TMPA) precipitation climatology (1998–2016, millimeters per day) for boreal summer (June, July, and August). Credit: Giovanni

    Analytical Features

    Giovanni includes many commonly used analytical and plotting capabilities for capturing spatial and temporal characteristics of data sets. Mapping options include time averaging (Figure 3), animation, precipitation accumulation (Figure 4), time-averaged overlay of two data sets, and user-defined climatology (Figure 2). For time series, options include area averaged, differences, seasonal, and Hovmöller diagrams (Figure 5).

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    Fig. 3. July 2016, the hottest month ever on record for the globe. Shown are Moderate Resolution Imaging Spectroradiometer (MODIS) day surface temperatures (in kelvins). Credit: Giovanni

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    Fig. 4. Accumulated rainfall (millimeters) from GPM Integrated Multisatellite Retrievals (IMERG) Final Run (version 4), showing a record-breaking flood event in Louisiana in August 2016. Credit: Giovanni

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    Fig. 5. Hovmöller diagram of TMPA monthly precipitation (millimeters per day) in the tropical region (5°S–5°N) showing El Niño–Southern Oscillation events between 1998 and 2016. Credit: Giovanni

    Cross sections, applicable to 3-D data sets from NASA’s Atmospheric Infrared Sounder (AIRS) instrument and Modern-Era Retrospective Analysis for Research and Applications (MERRA) data analysis program, include latitude-pressure, longitude-pressure, time-pressure (Figure 6), and vertical profile.

    For data comparison, Giovanni has built-in processing code for data sets that require measurement unit conversion and regridding. Commonly used comparison functions include map and time series differences, as well as correlation maps and X–Y scatterplots (area averaged or time averaged). Zonal means and histogram distributions can also be plotted.

    Visualization Features

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    Fig. 6. Quasi-biennial oscillation (QBO) seen from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), between 1980 and 2017. Credit: Giovanni

    Visualization features include interactive map area adjustment, animation, interactive scatterplots, data range adjustment, choice of color palette, contouring, and scaling (linear or log). The on-the-fly area adjustment feature (Figure 7) allows a user to examine a result map interactively and in detail without replotting data.

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    Fig. 7. El Niño reduced the phytoplankton productivity of Pacific coastal waters off Central America during the 2015–2016 winter, indicated by lower chlorophyll concentrations (milligrams per cubic meter). Credit: Giovanni

    Giovanni also provides animations, which are helpful for tracking the evolution of an event or seasonal changes. Interactive scatterplots allow identification and geolocation of a point of interest in a scatterplot. Adjustments of any of these plots provide customized options to users.

    Formats Facilitate Many Applications

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    Fig. 8. Time series of area-averaged TMPA monthly precipitation (millimeters per month) for California, showing record-breaking droughts (2012–2015), followed by 2016–2017, the wettest winter ever recorded in Northern California. Credit: Giovanni

    To support increasing socioeconomic and geographic information system (GIS) activities in Earth sciences, we have added shapefiles (a geospatial vector data format) for countries, states in the United States, and major watersheds around the world. Available functions for these shapefiles are time-averaged (Figure 4) and accumulated maps, area-averaged time series (Figure 8), and histograms. Land-sea masks have recently been added.

    All data files involved in Giovanni processing are listed and available for download in the lineage page generated simultaneously with the visualization. Available output image formats are PNG, GEOTIFF, and Keyhole Markup Language (KMZ), and they can be used for different applications and software packages. For example, KMZ files are conveniently imported into Google Earth (Figure 9), where a rich collection of overlays is available.

    10
    Fig. 9. NASA’s Aura satellite views nitrogen dioxide (NO2, as concentration per square centimeter) from Fort McMurray wildfires in Alberta, Canada, in May 2016 (imported from Google Earth as KMZ). Credit: Giovanni

    All input and output data are available in the Network Common Data Form (NetCDF) formats, which can be handled by many off-the-shelf software packages. Furthermore, users can bookmark URLs generated by Giovanni processing for reference, documentation, or sharing with other colleagues.

    Future Plans

    With the latest features and applications, Giovanni simplifies access, evaluation, and exploration of NASA satellite data sets. Despite these achievements, we still need to improve Giovanni to accommodate increasing demand for more analytical and plotting capabilities, more data sets, and advanced information technologies to make data exploration simple and productive.

    Future plans include visualization and analysis of satellite orbital data sets (Figure 10), more data sets from other data centers, additional analytical methods and visualization, and analysis of multisatellite and multisensor measurements.

    11
    Fig. 10. A sample of satellite orbital data sets from GPM’s Microwave Imager (GMI) showing surface precipitation of Tropical Storm Nanmadol on 3 July 2017. Credit: NASA Panoply

    Data sets in Giovanni currently consist of variables mapped on uniform space-time grid scales, so nongridded or satellite orbital data sets remain largely untapped, even though they commonly provide higher spatial resolution. Adding orbital data sets to Giovanni could aid research requiring increased data resolution and coverage.

    Data sets from other data centers and satellite missions will further enhance Giovanni for better understanding of Earth as an integrated system. Barriers still exist in the development of Giovanni for interdisciplinary studies and intercomparison among data sets. For example, terminologies in data sets can vary significantly between Earth science communities, requiring coordinated efforts to reach consensus and develop standards for uniform data products.

    The NASA-wide User Registration System (URS) is also expected to enhance the Giovanni user experience. For example, with URS, users can set frequently used preferences in their profiles, record and retrieve their personal history of data set exploration, and establish their own data collections.

    Data product developers can upload their test data and compare them with observations and other well-established data sets in Giovanni to identify issues in their products, a useful capability to improve data quality. Giovanni developers will also be able to better understand their users through profiles and other statistics collected from URS, so that they can develop more user-friendly services.

    In summary, a wide variety of new features is available now in Giovanni, but it remains a work in progress. Creating a community tool with such a large scope is challenging, and fully realizing this tool requires active participation from the user community. We encourage users to provide their opinions as Giovanni continues to evolve.

    Acknowledgments

    We recognize the team effort of all past and current members at GES DISC for their contributions to the development of Giovanni. We extend our thanks to data set algorithm developers and many users for their feedback and suggestions. GES DISC is funded by NASA’s Science Mission Directorate.

    References

    Acker, J. G., and G. Leptoukh (2007), Online analysis enhances use of NASA Earth science data, Eos Trans. AGU, 88(2), 14–17, https://doi.org/10.1029/2007EO020003.

    Berrick, S. W., et al. (2009), Giovanni: A Web service workflow-based data visualization and analysis system, IEEE Trans. Geosci. Remote Sens., 47(1), 106–113, https://doi.org/10.1109/TGRS.2008.2003183.

    Liu, Z., et al. (2007), Online visualization and analysis: A new avenue to use satellite data for weather, climate, and interdisciplinary research and applications, in Measuring Precipitation from Space: EURAINSAT and the Future, Adv. Global Change Res. Ser., vol. 28, edited by V. Levizzani et al., pp. 549–558, Springer, New York, https://doi.org/10.1007/978-1-4020-5835-6.

    Author Information

    Zhong Liu (email: zhong.liu-1@nasa.gov), NASA Goddard Earth Sciences Data and Information Services Center, Greenbelt, Md.; also at George Mason University Center for Spatial Information Science and Systems, Fairfax, Va.; and James Acker, NASA Goddard Earth Sciences Data and Information Services Center, Greenbelt, Md.; also at Adnet Systems, Inc., Bethesda, Md.
    Citation: Liu, Z., and J. Acker (2017), Giovanni: The bridge between data and science, Eos, 98, https://doi.org/10.1029/2017EO079299. Published on 24 August 2017.

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  • richardmitnick 1:29 pm on August 18, 2017 Permalink | Reply
    Tags: , Different Triggers Same Shaking, , Eos, Fault types differ between the two regions, , Quakes Pack More Punch in Eastern Than in Central United States   

    From Eos: “Quakes Pack More Punch in Eastern Than in Central United States” 

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    Eos

    8.18.17
    Kimberly M. S. Cartier

    A new finding rests on the recognition that fault types differ between the two regions. It helps explain prior evidence that human-induced quakes and natural ones behave the same in the nation’s center.

    1
    A broken angel statue lies among other damage on the roof of the Washington National Cathedral, Washington, D. C., after a magnitude 5.8 earthquake that impacted the eastern United States and Canada on 23 August 2011. Credit: AP Photo/J. Scott Applewhite

    Earthquakes in the eastern United States and Canada are many times more severe than central U.S. earthquakes of human or natural origin, earthquake scientists have found, highlighting a crucial need to separate the two regions when designing future earthquake hazard maps. The study separated the regions from the Mississippi-Alabama border up to the base of Lake Michigan, approximately 87°W.

    “People have never really compared these two regions very carefully,” said Yihe Huang, assistant professor of Earth and environmental sciences at the University of Michigan, Ann Arbor, and lead author of a study published in Science Advances on 2 August.

    Because earthquakes have occurred rarely in the central and eastern United States until recently, seismologists have not studied those areas as closely as they have more high-risk ones like the U.S. West Coast. “They are always taken as one region in the hazard models, but…if you look closely, they actually [are] very different,” she said. “We didn’t really think about this before.”

    Huang’s research shows that there is a fundamental and important difference in the stress released, and therefore in the hazard level, of central U.S. quakes compared with those in the eastern United States and Canada, said Gail Atkinson, professor of Earth sciences and Industrial Research Chair in Hazards from Induced Seismicity at Western University in London, Ontario, Canada.

    Different Triggers, Same Shaking

    Huang and her coauthors began their investigation questioning whether seismologists can use existing earthquake hazard models—developed using data from naturally occurring tectonic earthquakes—to accurately predict the severity of quakes induced by human activity.

    They expected the trigger mechanism to be a major source of uncertainty in hazard prediction models, but they found instead that the biggest difference was geography. Earthquakes they analyzed from the eastern United States and Canada along the Appalachians released 5–6 times more energy than their central counterparts. Consequently, Huang argued that “we should treat the central and eastern U.S. tectonic earthquakes differently in our hazard prediction.”

    Their study confirmed that earthquakes in the central United States released similar amounts of energy and shook the ground the same way whether they were induced or natural. So seismologists can use the same models to study them all, report Huang and her colleagues.

    “Within the central U.S., all of the earthquakes appear to be the same, and we’re really comparing apples and apples,” said William Ellsworth, professor of geophysics at Stanford University in Stanford, Calif., and a coauthor on the paper.

    “We don’t need to discriminate why the earthquake occurred to describe its shaking,” he said.

    Different Types of Stress Relief

    Why do the two regions produce earthquakes of such different severity? The reason, the researchers explained, is that the central and eastern regions release underground stress using different mechanisms. The way that ground layers shift and slide against each other to dissipate energy determines the violence of the stress release and strength of high-frequency motion aboveground, the shaking most relevant for engineering safety and seismic hazard assessment.

    Huang explained that in the central United States, seven of nine earthquakes they examined happened when chunks of Earth’s crust slid horizontally against each other along strike-slip faults. All eight of the eastern earthquakes they analyzed occurred at reverse faults, where the ground shifts vertically against the pull of gravity. Separating by region, Huang said, equates to separating by fault type.

    A comparison of earthquake magnitudes in eastern and central regions underscores the greater power of eastern temblors, according to Huang. The team’s list of natural events, reaching back more than 15 years, contains only one earthquake stronger than magnitude 5 in the central United States but three from the eastern United States. The strongest, an M5.8 quake in Mineral, Va., on 23 August 2011, caused significant property damage but only minor injuries.

    Ellsworth explained that industrial processes in the central and eastern United States, like the disposal of wastewater from oil production and hydraulic fracturing, may simply be speeding up the normal geologic processes nearby by releasing underground pressure that builds up naturally. “We might be speeding up the processes by hundreds of thousands of years,” he said.

    The researchers noted in their paper that wastewater injection is likely acting as a trigger for stress release but that subsequent shaking follows natural tectonic physics. Because the shaking is similar, Huang said, existing ground motion prediction equations can actually be used to predict the severity of induced earthquakes as long as they first account for the fault type at work.

    Improving Hazard Predictions Nationwide

    Now that this new work has revealed a significant difference in the types of earthquake-producing faults prevalent in the central and eastern regions, Huang said that she wants to conduct a broader investigation into seismic events nationwide to see if there are other overlooked patterns related to earthquake strength.

    In the meantime, the new recognition of an eastern versus central difference in typical fault type should help improve future hazard prediction maps and guide the construction of earthquake-safe structures, Ellsworth said.

    “The more accurate we can make that forecast,” he said, “the more it actually reduces the cost of ensuring seismic safety.”

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  • richardmitnick 11:03 am on August 18, 2017 Permalink | Reply
    Tags: A Closer Look at an Undersea Source of Alaskan Earthquakes, , , , Eos,   

    From Eos: “A Closer Look at an Undersea Source of Alaskan Earthquakes” 

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    Eos

    15 August 2017
    Daniel S. Brothers
    Peter Haeussler
    Amy East
    Uri ten Brink
    Brian Andrews
    Peter Dartnell
    Nathan Miller
    Jared Kluesner

    1
    All is calm in southern Alaska’s Lisianski Inlet in this 2015 view from the deck of the R/V Solstice. A systematic survey of the nearby Queen Charlotte–Fairweather Fault, the source of several major earthquakes, has produced valuable information on the fault’s structure and slip mechanisms. Credit: Daniel S. Brothers

    During the past century, movement along the Queen Charlotte–Fairweather fault, which lies for most of its length beneath the waters off southeastern Alaska and British Columbia, has generated at least seven earthquakes of magnitude 7 or greater. This includes a magnitude 8.1 earthquake in 1949, the largest ever recorded in Canada.

    Other events include a magnitude 7.8 earthquake in 1958 that dislodged a massive landslide above Lituya Bay, Alaska. The earthquake generated a tsunami that sent water 525 meters up the mountainside, a world record run-up [Miller, 1960]. The 2012 magnitude 7.8 Haida Gwaii earthquake, centered on Moresby Island, British Columbia, and the 2013 magnitude 7.5 earthquake near Craig, Alaska [Walton et al., 2015], increased awareness of the potential geologic hazards posed to residents of southeastern Alaska and western British Columbia.

    Together, these events highlight the need for a greater understanding of the Queen Charlotte–Fairweather fault and its history.

    Yet despite the dramatic effects of this fault’s activity, a near absence of high-resolution marine geophysical and geological data limits scientific understanding of its slip rate, earthquake recurrence interval, paleoseismic history, and rupture dynamics.

    The U.S. Geological Survey (USGS) has now completed a systematic examination of the tectonic geomorphology along a 500-kilometer-long undersea section of the Queen Charlotte–Fairweather fault that offers new insights into activity at this strike-slip boundary, where the North American and Pacific plates slide horizontally past each other.

    2
    Fig. 1. Recent geophysical surveys provided high-resolution seafloor depth data for the northernmost undersea portion of the Queen Charlotte–Fairweather fault (area outlined in red). The colored seafloor relief represents multibeam echo sounder data acquired along the continental shelf and slope in 2015 and 2016; the gray seafloor relief in deeper water west of the fault was acquired by the University of New Hampshire in 2005. Black boxes are locations of depth imagery shown in Figures 2a–2d. Purple lines represent high-resolution seismic reflection profiles that were acquired in 2016 aboard the R/V Norseman. One such profile (green line) is shown in Figure 3. AMT represents the Alaska-Aleutian megathrust, and ME indicates Mount Edgecumbe.

    A Complicated Boundary

    The Queen Charlotte–Fairweather fault system and its better known counterpart, the San Andreas fault (which is highly visible on land in California), form the boundary between the North American and Pacific tectonic plates. The Queen Charlotte–Fairweather fault system defines this plate boundary for a distance of more than 1,200 kilometers, from Yakutat, Alaska, to the Queen Charlotte Triple Junction, a confluence of three faults west of British Columbia (Figure 1). Within this system, the Queen Charlotte fault represents the underwater section and is widely recognized as one of the world’s most seismically active continent-ocean transform faults [Plafker et al., 1978; Bruns and Carlson, 1987; Nishenko and Jacob, 1990; Walton et al., 2015].

    The northern part of the boundary between the North American and Pacific plates is complicated by the collision of the Yakutat terrane, a block of crustal material surrounded by faults, with southern Alaska. In this region, the Pacific Plate begins to subduct, or plunge beneath, the North American Plate along a boundary known as the Alaska-Aleutian megathrust.

    The Fairweather fault is the only stretch of the fault system accessible by land. To the south of Icy Point, the Fairweather fault runs offshore, becoming the Queen Charlotte fault, which extends about 900 kilometers southward along the continental slope.

    Earlier studies estimated a slip rate of 41 to 58 millimeters per year on the Fairweather fault [Plafker et al., 1978; Bruns and Carlson, 1987; Elliot et al., 2010], but few direct observations of horizontal seafloor displacement existed [Bruns and Carlson, 1987] because of the absence of high-resolution seabed data.

    Geophysical Surveys

    In 2015, our team conducted two marine geophysical surveys, one aboard the research vessel R/V Solstice and a second on R/V Alaskan Gyre. We collected high-resolution seafloor depth data using multibeam sonar along the northernmost section of the fault. We also used a chirp subbottom profiler, which returns detailed images down to 50 meters beneath the seafloor.

    3
    The Queen Charlotte–Fairweather fault lies off the coast of southeastern Alaska. New imagery of a 400-kilometer-long undersea section of this transform fault provides a striking view of its structure and offers insights into activity at the boundary between the North American and Pacific tectonic plates. This perspective view of depth data acquired during recent surveys of the area shows the fault as it emerges from the Alaskan coast and stretches as a distinct line across the ocean floor. The color spectrum from red to purple represents increasing water depth.

    In 2016, two additional cruises (aboard R/V Medeia and R/V Norseman) extended data coverage of the Queen Charlotte–Fairweather fault an additional 325 kilometers southward. We again used multibeam sonar to map the ocean floor and multichannel seismic reflection to image deeper layers of sediment. Most recently, seismic reflection and chirp surveys were completed in July 2017 aboard the R/V Ocean Starr.

    In total, during 95 days of seagoing operations, we collected more than 5,000 square kilometers of high-resolution depth data, 9,400 kilometers of high-resolution multichannel seismic reflection profiles, and 500 kilometers of subbottom chirp data.

    A Clearer View of the Fault System

    Imagery from the surveys shows the fault in pristine detail, cutting straight across the seafloor, with offsetting seabed channels and submerged glacial valleys (Figure 2). The continuous knife-edge character of the fault is evident over the entire 500-kilometer-long survey area. At the same time, we can see several previously unknown features, including a series of subtle bends and steps in the fault that appear to form basins within the fault zone.

    4
    Fig. 2. High-resolution depth images at four locations along the Queen Charlotte fault show the morphological features of the fault and the continental slope. Red arrows indicate the relative sense of motion (see Figure 1 for locations).

    Because the surveys spanned four sections of the fault that ruptured in significant historical earthquakes, the results provide a unique catalog of geomorphic features commonly associated with active strike-slip faults.

    The Fairweather fault bends 20° as it extends southward across the shoreline near Icy Point (Figures 1 and 2a) and then continues southward at a 340° strike along the shelf edge as a single fault trace for another 150 kilometers.

    Numerous submarine canyons, gullies, and ridges have been displaced or warped along the fault. Fault valleys parallel to the margin locally separate geomorphically distinct upper and lower sections of the continental slope (Figures 2b and 3). A Pleistocene basaltic-andesitic volcanic edifice exposed at the seabed extends from Mount Edgecumbe to the shelf edge (Figure 2b).

    West of southern Baranof Island, the fault takes a series of subtle 3° to 5° right steps and bends that form en echelon pull-apart basins along the shelf edge (Figure 2c). The fault continues southward as a single lineament but exhibits a subtle warp and series of westward steps displacing submarine canyon valleys (Figure 2d) before crossing Noyes Canyon and extending southward into Canadian waters [see, e.g., Barrie et al., 2013].

    5
    Fig. 3. A seismic reflection profile acquired in August 2016 highlights the structure and stratigraphy of the continental slope.

    Fault Slip Rates

    The offset features along the seabed provide important information for reconstructing past fault motion. From the ages of these features we can calculate the average rate of motion along the fault, then estimate the typical recurrence interval for large earthquakes.

    For example, the southern margin of the Yakobi Sea Valley has been sliced and translated about 925 meters by the linear, knife-edge fault trace (Figure 2a). Ice likely retreated from the valley about 17,000 years ago. Thus, the slip rate of the Queen Charlotte–Fairweather fault across the Yakobi Sea Valley exceeds 50 millimeters per year: one of the fastest-slipping continent-ocean transform faults in the world [Brothers et al., 2015].

    Furthermore, we observe coincidence between the pull-apart basins shown in Figure 2c and the northernmost extent of the 2013 Craig earthquake, implying that changes in fault geometry likely influenced the length of rupture propagation [e.g., Walton et al., 2015].

    Future Plans

    The USGS, the Geological Survey of Canada, the Sitka Sound Science Center, and the University of Calgary will jointly lead a research cruise in September 2017 to collect sediment cores along the Queen Charlotte–Fairweather fault in Canadian and U.S. territories to constrain the sedimentation history along the margin and date features offset by fault motion.

    Overall, this project has shown that the Queen Charlotte–Fairweather fault is an ideal laboratory to examine the tectonic geomorphology of a major strike-slip fault and the associated processes responsible for generating offshore hazards.

    Acknowledgments

    We thank J. Currie, G. Hatcher, R. Wyland, A. Balster-Gee, P. Hart, J. Conrad, T. O’Brien, A. Nichols, M. Walton, R. Marcuson, and E. Moore of the U.S. Geological Survey (USGS); K. Green of the Alaska Department of Fish and Game; G. Greene of Moss Landing Marine Laboratories; V. Barrie and K. Conway of the Geological Survey of Canada; and the crews of the R/V Solstice, R/V Medeia, R/V Norseman, R/V Ocean Starr, and R/V Alaskan Gyre. We also thank J. Warrick, R. von Huene, J. Watt, and an anonymous reader for helpful reviews. The USGS Coastal and Marine Geology Program funded this study. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. government.

    References

    Barrie, J. V., K. W. Conway, and P. T. Harris (2013), The Queen Charlotte fault, British Columbia: Seafloor anatomy of a transform fault and its influence on sediment processes, Geo Mar. Lett., 33, 311–318, https://doi.org/10.1007/s00367-013-0333-3.

    Brothers, D. S., et al. (2015), High-resolution geophysical constraints on late Pleistocene–Present deformation history, seabed morphology, and slip-rate along the Queen Charlotte-Fairweather fault, offshore southeastern Alaska, Abstract NH23B-1882 presented at 2015 Fall Meeting, AGU, San Francisco, Calif.

    Bruns, T. R., and P. R. Carlson (1987), Geology and petroleum potential of the southeast Alaska continental margin, in Geology and Petroleum Potential of the Continental Margin of Western North America and Adjacent Ocean Basins, Beaufort Sea to Baja California, Earth Sci. Ser., vol. 9, edited by D. W. Scholl, A. Grantz, and J. G. Vedder, pp. 269–282, Circum-Pac. Counc. for Energy and Miner. Resour., Houston, Texas.

    Elliot, J. L., et al. (2010), Tectonic block motion and glacial isostatic adjustment in southeast Alaska and adjacent Canada constrained by GPS measurements, J. Geophys. Res., 115, B09407, https://doi.org/10.1029/2009JB007139.

    Miller, D. J. (1960), Giant waves in Lituya Bay, Alaska, U.S. Geol. Surv. Prof. Pap., 354-C, 51–86, scale 1:50,000.

    Nishenko, S. P., and K. H. Jacob (1990), Seismic potential of the Queen Charlotte-Alaska-Aleutian seismic zone, J. Geophys. Res., 95(B3), 2511–2532, https://doi.org/10.1029/JB095iB03p02511.

    Plafker, G., et al. (1978), Late Quaternary offsets along the Fairweather fault and crustal plate interactions in southern Alaska, Can. J. Earth Sci., 15(5), 805–816, https://doi.org/10.1139/e78-085.

    Walton, M. A. L., et al. (2015), Basement and regional structure along strike of the Queen Charlotte fault in the context of modern and historical earthquake ruptures, Bull. Seismol. Soc. Am., 105, 1090–1105, https://doi.org/10.1785/0120140174.

    Author Information

    Daniel S. Brothers (email: dbrothers@usgs.gov; @DBrothersSC), Pacific Coastal and Marine Science Center, U.S. Geological Survey (USGS), Santa Cruz, Calif.; Peter Haeussler, Alaska Science Center, USGS, Anchorage; Amy East, Pacific Coastal and Marine Science Center, USGS, Santa Cruz, Calif.; Uri ten Brink and Brian Andrews, Woods Hole Science Center, USGS, Mass.; Peter Dartnell, Pacific Coastal and Marine Science Center, USGS, Santa Cruz, Calif.; Nathan Miller, Woods Hole Science Center, USGS, Mass.; and Jared Kluesner, Pacific Coastal and Marine Science Center, USGS, Santa Cruz, Calif.
    Citation: Brothers, D. S., P. Haeussler, A. East, U. ten Brink, B. Andrews, P. Dartnell, N. Miller, and J. Kluesner (2017), A closer look at an undersea source of Alaskan earthquakes, Eos, 98, https://doi.org/10.1029/2017EO079019. Published on 15 August 2017.

    © 2017. The authors. CC BY-NC-ND 3.0

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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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    Eos

    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.

    1
    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.

    2
    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.

    3
    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.

    4
    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.

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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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    Eos

    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.

    1
    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?

    2
    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.

    4
    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.

    5
    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.

    6
    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” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    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 .

    Please help promote STEM in your local schools.

    STEM Icon

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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.

     
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