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  • richardmitnick 2:13 pm on July 24, 2017 Permalink | Reply
    Tags: , “Our geological record from a cave illustrates that we still cannot predict when the next earthquake will happen.”, , Geology, Looking for tsunami records in a sea cave,   

    From Rutgers: “Sea Cave Preserves 5,000-Year Snapshot of Tsunamis” 

    Rutgers University
    Rutgers University

    July 19, 2017
    Ken Branson

    Record tells us we don’t know much about predicting earthquakes that cause tsunamis.

    An international team of scientists digging in a sea cave in Indonesia has discovered the world’s most pristine record of tsunamis, a 5,000-year-old sedimentary snapshot that reveals for the first time how little is known about when earthquakes trigger massive waves.

    “The devastating 2004 Indian Ocean tsunami caught millions of coastal residents and the scientific community off-guard,” says co-author Benjamin Horton, a professor in the Department of Marine and Coastal Sciences at Rutgers University-New Brunswick.“Our geological record from a cave illustrates that we still cannot predict when the next earthquake will happen.”

    “Tsunamis are not evenly spaced through time,” says Charles Rubin, the study’s lead author and a professor at the Earth Observatory of Singapore, part of Nanyang Technological University. “Our geological record from a cave illustrates that we still cannot predict when the next earthquake will happen.” There can be long periods between tsunamis, but you can also get major tsunamis that are separated by just a few decades.”

    The discovery, reported in the current issue of Nature Communications, logs a number of firsts: the first record of ancient tsunami activity found in a sea cave; the first record for such a long time period in the Indian Ocean; and the most pristine record of tsunamis anywhere in the world.

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    The stratigraphy of the sea cave in Sumatra excavated by scientists from the Earth Observatory of Singapore, Rutgers and other institutions. The lighter bands are sand deposited by tsunamis over a period of 5,000 years; the darker bands are organic material. Photo: Earth Observatory of Singapore.

    The discovery was made in a sea cave on the west coast of Sumatra in Indonesia, just south of the city of Banda Aceh, which was devastated by the tsunami of December 2004. The stratigraphic record reveals successive layers of sand, bat droppings and other debris laid down by tsunamis between 7,900 and 2,900 years ago. The stratigraphy since 2,900 years ago was washed away by the 2004 tsunami.

    The L-shaped cave had a rim of rocks at the entrance that trapped successive layers of sand inside. The researchers dug six trenches and analyzed the alternating layers of sand and debris using radio carbon dating. The researchers define “pristine” as stratigraphic layers that are distinct and easy to read. “You have a layer of sand and a layer of organic material that includes bat droppings, so simply it is a layer of sand and a layer of bat crap, and so on, going back for 5,000 years,” Horton says.

    The record indicates that 11 tsunamis were generated during that period by earthquakes along the Sunda Megathrust, the 3,300-mile-long fault running from Myanmar to Sumatra in the Indian Ocean. The researchers found there were two tsunami-free millennia during the 5,000 years, and one century in which four tsunamis struck the coast. In general, the scientists report, smaller tsunamis occur relatively close together, followed by long dormant periods, followed by great quakes and tsunamis, such as the one that struck in 2004.

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    Using flourescent lights, Kerry Sieh and Charles Rubin of the Earth Observatory of Singapore look for charcoal and shells for radiocarbon dating. Photo: Earth Observatory of Singapore.

    Rubin, Horton and their colleagues were studying the seismic history of the Sunda Megathrust, which was responsible for the 2004 earthquake that triggered the disastrous tsunami. They were looking for places to take core samples that would give them a good stratigraphy. This involves looking for what Horton calls “depositional places” – coastal plains, coastal lake bottoms, any place to plunge a hollow metal cylinder six or seven meters down and produce a readable sample. But for various reasons, there was no site along the southwest coast of Sumatra that would do the job. But Patrick Daly, an archaeologist at EOS who had been working on a dig in the coastal cave, told Rubin and Horton about it and suggested it might be the place they were looking for.

    Looking for tsunami records in a sea cave was not something that would have occurred to Horton, and he says Daly’s professional generosity – archaeologists are careful about who gets near their digs – and his own and Rubin’s openness to insights from other disciplines made the research possible. Horton says this paper may be the most important in his career for another reason.

    “A lot of (the research) I’ve done is incremental,” he says. “I have a hypothesis, and I do deductive science to test the hypothesis. But this is really original, and original stuff doesn’t happen all that often.”

    See the full article here .

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    rutgers-campus

    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

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    As a ’67 graduate of University college, second in my class, I am proud to be a member of

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  • richardmitnick 8:39 am on July 14, 2017 Permalink | Reply
    Tags: , Geology, Slow Earthquakes Occur Continuously in the Alaska-Aleutian Subduction Zone,   

    From UC Riverside: “Slow Earthquakes Occur Continuously in the Alaska-Aleutian Subduction Zone” 

    UC Riverside bloc

    UC Riverside

    July 12, 2017
    Iqbal Pittalwala

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    Image shows tremor sources and low frequency earthquake distribution in the study region and historic large earthquakes in the Alaska-Aleutian subduction zone. Each red star represents the location of 1 min tremor signal determined by the beam back projection method, and the black stars show three visually detected low frequency earthquakes located using arrival times of body waves. Image credit: Ghosh lab, UC Riverside.

    Seismologists at the University of California, Riverside studying earthquakes in the seismically and volcanically active Alaska-Aleutian subduction zone have found that “slow earthquakes” are occurring continuously, and could encourage damaging earthquakes.

    Slow earthquakes are quiet, can be as large as magnitude 7, and last days to years. Taking place mainly at the boundary between tectonic plates, they happen so slowly that people don’t feel them. A large slow earthquake is typically associated with abundant seismic tremor—a continuous weak seismic chatter—and low frequency (small and repeating) earthquakes.

    “In the Alaska-Aleutian subduction zone, we found seismic tremor, and visually identified three low frequency earthquakes,” said Abhijit Ghosh, an assistant professor of Earth sciences, who led the research published recently in Geophysical Research Letters. “Using them as templates, we detected nearly 1,300 additional low frequency earthquakes. Slow earthquakes may play an important role in the earthquake cycles in this subduction zone.”

    The Alaska-Aleutian subduction zone, which stretches from the Gulf of Alaska to the Kamchatka Peninsula in the Russian Far East, is one of the most active plate boundaries in the world. It is 3,800 km long and forms the plate boundary between the Pacific and North American plates. In the last 80 years, four massive earthquakes (greater than magnitude 8) have occurred here.

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    Abhijit Ghosh lands in Alaska to do field work. Photo credit: Ghosh lab, UC Riverside.

    Ghosh explained that tectonic tremor—which causes a weak vibration of the ground—and low frequency earthquakes are poorly studied in the Alaska-Aleutian subduction zone due to limited data availability, difficult logistics, and rugged terrain.

    But using two months of high-quality continuous seismic data recorded from early July-September 2012 at 11 stations in the Akutan Island, Ghosh and his graduate student, Bo Li, detected near-continuous tremor activity with an average of 1.3 hours of tectonic tremor per day using a “beam back projection” method—an innovative array-based method Ghosh developed to automatically detect and locate seismic tremor. Using the seismic arrays the method continuously scans the subsurface for any seismic activity. Just like a radar antenna, it determines from which direction the seismic signal originates and uses that information to locate it. Practically, it can track slow earthquakes minute-by-minute.

    Ghosh and Li found that tremor sources were clustered in two patches with a nearly 25 km gap in between them, possibly indicating that frictional properties determining earthquake activities change laterally along this area. Ghosh explained that this gap impacts the region’s overall stress pattern and can affect earthquake activity nearby.

    “In addition, slow earthquakes seem to have ‘sweet spots’ along the subduction fault that produces majority of the tremor activity,” he said. “We found that the western patch has a larger depth range and shows higher tremor source propagation velocities. More frequent tremor events and low frequency earthquakes in the western patch may be a result of higher fluid activity in the region and indicate a higher seismic slip rate than the eastern region.”

    Ghosh, Li, and their collaborators in multiple institutions in the United States have taken the next step by installing three additional seismic arrays in a nearby island to simultaneously image the subduction fault and volcanic system.

    “This ambitious experiment will provide new insights into the seismic activity and subduction processes in this region,” Ghosh said.

    The study [Geophysical Reseach Letters] was supported by grants to Ghosh from the National Science Foundation-Division of Earth Sciences, EarthScope, the United States Geological Survey, and the Alaska Volcano Observatory.

    See the full article here .

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    UC Riverside Campus

    The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

    Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

    We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

     
  • richardmitnick 3:13 pm on July 11, 2017 Permalink | Reply
    Tags: , , , , , Cornelia crater, , Geology, Haulani Crater, Marcia crater, , Terrain Clues to Ice in the Outer System, The human expansion into the Solar System will demand our being able to identify sources of water, Vesta   

    From Centauri Dreams: “Terrain Clues to Ice in the Outer System” 

    Centauri Dreams

    July 11, 2017
    Paul Gilster

    The human expansion into the Solar System will demand our being able to identify sources of water, a skill we’re honing as explorations continue. On Mars, for example, the study of so-called ‘pitted craters’ has been used as evidence that the low latitude regions of the planet, considered its driest, nonetheless have a layer of underlying ice. The Dawn spacecraft discovered similar pitted terrain on Vesta, as you can see in the image below.

    NASA/Dawn Spacecraft

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    These enhanced-color views from NASA’s Dawn mission show an unusual “pitted terrain” on the floors of the craters named Marcia (left) and Cornelia (right) on the giant asteroid Vesta. The views show that the physical properties or composition of the material in which these pits form is different from crater to crater. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/JHUAPL.

    Vesta’s Marcia crater contains the largest number of pits on the asteroid. The 70-kilometer feature is also one of the youngest craters found there. So what accounts for this kind of terrain? Perhaps the water that formed the pits came from Vesta itself. Another possibility: Low-speed collisions with carbon-rich meteorites could have deposited hydrated materials on the surface, to be released in the heat of subsequent high-speed collisions within the asteroid belt. An explosive degassing into space could explain such pothole-like depressions.

    But Dawn wasn’t through when it left Vesta, and what it has found at Ceres is proving invaluable at understanding what appears to be a common marker of volatile-rich material. In new work from Hanna Sizemore [Geophysical Reseach Letters] (Planetary Science Institute) and colleagues, we learn that Ceres is home to the same kind of pitted terrain. As Sizemore notes:

    “Now, we’ve found this same type of morphological feature on Ceres, and the evidence suggests that ice in the Cerean subsurface dominated the formation of pits there. Finding this type of feature on three different bodies suggests that similar pits might be found on other asteroids we will explore in the future, and that pitted materials may mark the best places to look for ice on those asteroids.”

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    Haulani Crater, Ceres, showing abundant pitted materials on the crater floor. Similar pitted materials have previously been identified on Mars and Vesta, and are associated with rapid volatile release following impact. Their discovery on Ceres indicates pitted materials may be a common morphological indicator of volatile-rich materials in the asteroid belt. Haulani Crater is 34 km in diameter. Color indicates topography. Credit: NASA/MPS/PSI/Thomas Platz.

    Sizemore’s team studied the formation of pitted craters on Ceres through numerical models that explored the role of water ice and other volatiles. The morphological similarities between the Ceres features and what has been found on Mars and Vesta are striking. With water ice evidently significant in pit development on two asteroids and a planet, similar terrains will be of clear interest for future missions in terms of in situ resource utilization.

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    Pitted terrain on Mars as seen by HiRISE aboard the Mars Reconnaissance Orbiter. Credit: NASA/JPL/University of Arizona.

    Centauri Dreams


    See the full article here .

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    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 1:03 pm on July 8, 2017 Permalink | Reply
    Tags: "Answers in Genesis", A great test case, , , , Geology   

    From ars technica: “Creationist sues national parks, now gets to take rocks from Grand Canyon” a Test Case Too Good to be True 

    Ars Technica
    ars technica

    7/7/2017
    Scott K. Johnson

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    Scott K. Johnson

    “Alternative facts” aren’t new. Young-Earth creationist groups like Answers in Genesis believe the Earth is no more than 6,000 years old despite actual mountains of evidence to the contrary, and they’ve been playing the “alternative facts” card for years. In lieu of conceding incontrovertible geological evidence, they sidestep it by saying, “Well, we just look at those facts differently.”

    Nowhere is this more apparent than the Grand Canyon, which young-Earth creationist groups have long been enamored with. A long geologic record (spanning almost 2 billion years, in total) is on display in the layers of the Grand Canyon thanks to the work of the Colorado River. But many creationists instead assert that the canyon’s rocks—in addition to the spectacular erosion that reveals them—are actually the product of the Biblical “great flood” several thousand years ago.

    Andrew Snelling, who got a PhD in geology before joining Answers in Genesis, continues working to interpret the canyon in a way that is consistent with his views. In 2013, he requested permission from the National Park Service to collect some rock samples in the canyon for a new project to that end. The Park Service can grant permits for collecting material, which is otherwise illegal.

    Snelling wanted to collect rocks from structures in sedimentary formations known as “soft-sediment deformation”—basically, squiggly disturbances of the layering that occur long before the sediment solidifies into rock. While solid rock layers can fold (bend) on a larger scale under the right pressures, young-Earth creationists assert that all folds are soft sediment structures, since forming them doesn’t require long periods of time.

    The National Park Service sent Snelling’s proposal out for review, having three academic geologists who study the canyon look at it. Those reviews were not kind. None felt the project provided any value to justify the collection. One reviewer, the University of New Mexico’s Karl Karlstrom, pointed out that examples of soft-sediment deformation can be found all over the place, so Snelling didn’t need to collect rock from a national park. In the end, Snelling didn’t get his permit.

    In May, Snelling filed a lawsuit alleging that his rights had been violated, as he believed his application had been denied by a federal agency because of his religious views. The complaint cites, among other things, President Trump’s executive order on religious freedom.

    That lawsuit was withdrawn by Snelling on June 28. According to a story in The Australian, Snelling withdrew his suit because the National Park Service has relented and granted him his permit. He will be able to collect about 40 fist-sized samples, provided that he makes the data from any analyses freely available.

    Not that anything he collects will matter. “Even if I don’t find the evidence I think I will find, it wouldn’t assault my core beliefs,” Snelling told The Australian. “We already have evidence that is consistent with a great flood that swept the world.”

    Again, in actuality, that hypothesis is in conflict with the entirety of Earth’s surface geology.

    Snelling says he will publish his results in a peer-reviewed scientific journal. That likely means Answers in Genesis’ own Answers Research Journal, of which he is editor-in-chief.

    See the full article here .

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    Ars Technica was founded in 1998 when Founder & Editor-in-Chief Ken Fisher announced his plans for starting a publication devoted to technology that would cater to what he called “alpha geeks”: technologists and IT professionals. Ken’s vision was to build a publication with a simple editorial mission: be “technically savvy, up-to-date, and more fun” than what was currently popular in the space. In the ensuing years, with formidable contributions by a unique editorial staff, Ars Technica became a trusted source for technology news, tech policy analysis, breakdowns of the latest scientific advancements, gadget reviews, software, hardware, and nearly everything else found in between layers of silicon.

    Ars Technica innovates by listening to its core readership. Readers have come to demand devotedness to accuracy and integrity, flanked by a willingness to leave each day’s meaningless, click-bait fodder by the wayside. The result is something unique: the unparalleled marriage of breadth and depth in technology journalism. By 2001, Ars Technica was regularly producing news reports, op-eds, and the like, but the company stood out from the competition by regularly providing long thought-pieces and in-depth explainers.

    And thanks to its readership, Ars Technica also accomplished a number of industry leading moves. In 2001, Ars launched a digital subscription service when such things were non-existent for digital media. Ars was also the first IT publication to begin covering the resurgence of Apple, and the first to draw analytical and cultural ties between the world of high technology and gaming. Ars was also first to begin selling its long form content in digitally distributable forms, such as PDFs and eventually eBooks (again, starting in 2001).

     
  • richardmitnick 11:59 am on July 8, 2017 Permalink | Reply
    Tags: , , Geology, Meteorology, , The Martian meteorite of Tissint   

    From NS: “Why Morocco loves its meteorites” 

    NewScientist

    New Scientist

    30 June 2017
    Sandrine Ceurstemont

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    A hotspot for space rocks. Sandrine Ceurstemont

    In Morocco’s High Atlas mountains, the twin lakes of Isli and Tislit (nicknamed the Moroccan Romeo and Juliet) have an unusual origin. Abderrahmane Ibhi from Ibn Zohr University in Agadir found strong evidence in 2013 that they were impact craters, formed when an asteroid hurtling towards Earth split in two about 40,000 years ago. “It was over 100 metres wide,” says Ibhi. “It’s the biggest asteroid to fall in Morocco.”

    Large space rocks can cause destruction or alter the landscape if they hit Earth. Today, the world’s Asteroid Day, Ibhi gave a talk about how to protect our planet from killer asteroids. “When they are over 10 metres wide, they can be dangerous,” he says.

    Luckily, space rocks rarely hit Earth. And double impacts are even less common: there are only three other known cases worldwide. But in recent years, the already otherworldly rocky land and desert close to Tata in southern Morocco has been defying the odds. From chunks of asteroids to pieces of the moon, more space rocks have been recovered in Morocco than in other countries of a similar size, with 95 per cent of them coming from around Tata.

    Rare finds

    It has been home to several rare finds, too. The most famous – the Martian meteorite of Tissint – blasted through the night sky in July 2011, scattering pieces that were collected over the following months.

    2
    http://www.mirror.co.uk/news/technology-science/science/tissint-martian-meteorite-which-landed-in-morocco-1373528

    It’s one of five rocks from the Red Planet ever to be found on Earth, and the first to carry traces of Martian soil.

    Ibhi and his team have been trying to work out why the area is such a hotspot. One reason seems to be the landscape: meteorites are easily revealed by windswept sand, in which their dark colour also makes them stand out. And a dry climate helps preserve them far better than a humid one.

    Then there’s the well-distributed population, which gives people a greater chance of stumbling upon them. In Tata, several villages are close together and many nomads live in the desert, explains team member Fouad Khiri. In addition, Morocco’s political stability is a plus, making it safer than in other countries to wander around searching for meteorites.

    But the biggest factor is a surprise: local knowledge. Since 2006, Ibhi has been organising workshops to teach people how to identify space rocks. Many nomads are now aware, for example, that looking for a particular combination of features that may mark them out is key.

    One of the telltale signs is a black skin, or fusion crust, formed by the fiery journey through the atmosphere. But desert rocks can appear similar, given that they too can have a dark surface from the extreme heat. Looking for marks that resemble thumbprints, caused by wind sculpting the rock during its journey, is a helpful clue.

    Space rocks from asteroids – the most common type – also have circular grains across their surface composed of molten minerals. “I always bring meteorites along so that people can take a close look and feel them,” says Ibhi.

    See the full article here .

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  • richardmitnick 5:33 pm on June 21, 2017 Permalink | Reply
    Tags: , Earthquake in Greenland triggers fatal landslide-induced tsunami, Geology,   

    From temblor: “Earthquake in Greenland triggers fatal landslide-induced tsunami” 

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    temblor

    June 19, 2017
    David Jacobson

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    This picture shows the settlement of Nuugaatsiaq, which was hit by a tsunami over the weekend. The tsunami was triggered by a landslide following a M=4.1 earthquake. (Photo from: knr.gl)

    Over the weekend, a M=4.1 earthquake on Greenland’s western coast caused a massive landslide, triggering a tsunami that inundated small settlements on the coast. At this stage, four people are feared to have died, nine others were injured, and 11 buildings were destroyed. In the hardest hit village, Nuugaatsiag, which is home to around 100 people, 40 people have been evacuated to Uummannaq, the eleventh-largest town in Greenland (see picture below).

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    This Temblor map shows the location of the M=4.1 earthquake on the western coast of Greenland. Despite its small magnitude, the quake caused a landslide, which triggered a tsunami that killed four people.

    While this earthquake appears to be tectonic in nature, according to Professor Meredith Nettles of the Lamont-Doherty Earth Observatory at Columbia University, Greenland also experiences what are known as glacial earthquakes. Glacial earthquakes are a relatively new class of seismic event, and are often linked to the calving of large outlet glaciers. While this type of event has also been observed in Antarctica, the majority have been recorded off the coast of Greenland, and show a strong seasonality, with most of them occurring late in the summer.

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    This photo shows Uummannaq, the eleventh-largest town in Greenland. This is where 40 people were evacuated to from Nuugaatsiaq following the tsunami over the weekend.

    Because glacial earthquakes have a different mechanism than normal earthquakes, standard earthquake monitoring techniques cannot be used to detect them, which explains why they were not known about until 2003. Additionally, while a tectonic M=5 quake typically lasts about 2 seconds, a comparable M=5 glacial earthquake can emit long-period (great than 30 seconds) seismic waves. It is because of this, that they have a separate classification.

    In order for a glacial earthquake to occur, a large-scale calving event has to take place. When a glacier calves, there is both a sudden change in glacial mass and motion. While a glacier is technically a river of ice, meaning it slowly flows downhill, when a large calving event take place, there is a brief period when horizontal motion reverses. Couple this with a downward deflection of the glaciers terminus, which causes a upward force on earth’s surface, and you have the recipe for a glacial earthquake. These earthquakes tend to be M=4.6-5.1.

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    This figure, from Nettles and Ekstrom, 2010 shows 252 glacial earthquakes in Greenland from 1993–2008, detected and located using the surface-wave detection
    algorithm.

    Despite the fact that this tectonic quake was by no means large, it was big enough to trigger a massive landslide into the ocean, and the ensuing displacement of water was enough to form a tsunami that devastated parts of Nuugaatsiag. Prof. Nettles said to us, “The M=4.1 earthquake does not explain the large, long-period (slow) seismic signal detected by seismometers around the globe. The long-period signal appears to be due to a landslide, and the time of the long-period signal is later than the time of the high-frequency (earthquake) signal. It is possible the earthquake triggered the landslide.” What this means is that both the earthquake and landslide generated seismic signals, but that the earthquake signal appeared first, suggesting the quake triggered the slide. The video below shows a view of the landslide, while the photos show the landslide and the devastation caused by the tsunami. In response to this event, and the risk of aftershocks, people have been advised to stay away from the coastline.

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    This picture, taken by the Arctic Command shows part of the landslide that triggered the deadly tsunami.

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    This photo shows damage in Nuugaatsiaq, following a deadly tsunami over the weekend. (Photo from: Olina Angie K Nielsen via Facebook)

    References
    Geological Survey of Denmark and Greenland (GEUS)

    Meredith Nettles and Goran Ekstrom, Glacial Earthquakes in Greenland and Antarctica, Annu. Rev. Earth Planet. Sci. 2010. 38:467–91, doi: 10.1146/annurev-earth-040809-152414

    T. Murray, M. Nettles, N. Selmes, L. M. Cathles, J. C. Burton, T. D. James, S. Edwards, I. Martin, T. O’Farrell, R. Aspey, I. Rutt, T. Baugé, Reverse glacier motion during iceberg calving and the cause of glacial earthquakes, sciencemag.org/content/early/recent / 25 June 2015 / Page 1 / 10.1126/science.aab0460

    2015 Washington Post article by Chris Mooney titled “Giant earthquakes are shaking Greenland — and scientists just figured out the disturbing reason why” – Link

    2015 NPR article titled “Study Reveals What Happens During A ‘Glacial Earthquake” – Link

    See the full article here .

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    You can help many citizen scientists in detecting earthquakes and getting the data to emergency services people in affected area.
    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    BOINCLarge

    BOINC WallPaper

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

     
  • richardmitnick 4:54 pm on June 16, 2017 Permalink | Reply
    Tags: , , Geology, M=6.3 earthquake in the Aegean Sea near the Greece-Turkey border causes injuries and damage,   

    From temblor: “M=6.3 earthquake in the Aegean Sea near the Greece-Turkey border causes injuries and damage” 

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    temblor

    1
    Vatera, in southern Lesbos experienced strong shaking from today’s M=6.3 earthquake. Numerous reports of damage have come in from this tourist hotspot in the eastern Aegean Sea. (Photo from: villapouloudia.gr)

    At 3:28 p.m. local time, a M=6.3 earthquake struck just south of the Greek Island of Lesbos (Lesvos), near the international border with Turkey. So far, there have been 33 aftershocks in close proximity to the mainshock, with the largest being a M=4.9. According to the USGS, severe shaking was felt close to the epicenter, and there are numerous reports of damage on Lesbos, a popular tourist hotspot (see video below). Based on the USGS PAGER system, fatalities are unlikely, while economic losses are estimated to be between $10-100 million.

    2
    This Temblor map shows the location of today’s M=6.3 earthquake south of Greek island of Lesbos. The faults on Lesbos’ southern coastline have been added to this map as they are the closest mapped active faults to today’s epicenter. Having said that, today’s quake, which was extensional in nature, likely occurred on a different structure.

    The Greek island of Lesbos, is home to approximately 87,000 people, making it the most populated in the Eastern Aegean. The tectonic activity in the area is associated with the broader evolution of the Aegean Sea. Along Lesbos’ southern coastline, and extending offshore are several active faults with components of both left-lateral strike-slip and extensional motion. The main faults, which have been added to the Temblor map above are the Polichnitos-Plomari and Aghios Isidoros-Cape Magiras faults. The Polichnitos-Plomari Fault is primarily extensional, though it also has a strike-slip component. Activity along it is related to theremal activity from the nearby Polichnitos geothermal field. The Aghios Isidoros-Cape Magiras Fault on the other hand is primarily extensional with a small amount of strike-slip motion. While these faults are close to the epicenter of today’s quake, based on the strike of the event, which was almost purely extensional it likely occurred on an additional, unmapped structure within the Aegean Sea.

    Due to the quake’s moderate magnitude, and shallow (9 km) depth, shaking was widely felt across the region, including in Athens, the Turkish Cities of Izmir and Istanbul, and Sofia, the capital of Bulgaria. Based on the USGS Shakemap and felt reports from the European-Mediterranean Seismological Centre, over 50 million people were exposed to some degree of shaking. However, damage appears to be isolated to the island of Lesbos, where building facades have come down, and 10 people have been injured.

    The video below shows damage sustained on Lesbos in today’s M=6.3 earthquake

    In addition to the M=6.3 mainshock, and the 33 aftershocks in close proximity, there also may have been two remote, dynamically-triggered aftershocks, up to 75 km away. One of these, a M=3.3 10 minutes after the mainshock was less than 15 km from Izmir. While it is possible that these quakes are incorrectly located, it is possible that they are remote aftershocks.

    Based on the Global Earthquake Activity Rate (GEAR) model, which is available in Temblor, today’s M=6.3 earthquake should not be considered surprising. This model, which uses global strain rates and seismicity since 1977 forecasts what the likely earthquake magnitude is in your lifetime anywhere on earth. From the Temblor map below, one can see that in the location of today’s quake, a M=6.5+ is possible. Therefore, while this earthquake was damaging and caused injuries, a larger quake in the region could happen, resulting in more extreme damage.

    3
    This Temblor map shows the Global Earthquake Activity Rate (GEAR) model for much of the area around the Aegean Sea. From this map, one can see that in the area around today’s M=6.3 earthquake, a M=6.5+ quake is possible. This map also shows a possible remote aftershock and the cities of Athens, Izmir, Istanbul, and Sofia, where shaking from today’s quake was felt.

    References
    European-Mediterranean Seismological Centre (EMSC)
    Chatzipetros, A., Kiratzi, A., Sboras, S., Zouros, N., Pavlides, S., Active Faulting in the nore-eastern Aegean Sea Islands, Tectonophysics 597-598 (2013) 106-122
    USGS

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    You can help many citizen scientists in detecting earthquakes and getting the data to emergency services people in affected area.
    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    BOINCLarge

    BOINC WallPaper

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

     
  • richardmitnick 4:41 pm on June 16, 2017 Permalink | Reply
    Tags: , , Geology, , Yellowstone earthquake swarm   

    From temblor: “M=4.4 earthquake highlights in progress seismic swarm in Yellowstone National Park” 

    1

    temblor

    1
    The western part of Yellowstone National Park experienced a M=4.4 earthquake yesterday evening. This quake is part of a seismic swarm which began on June 12. According to the University of Utah, seismic swarms make up approximately 50% of the seismicity around the Yellowstone region. (Photo from: visitmt.com)

    Yesterday, at 6:48 p.m. local time, a M=4.4 earthquake struck the western edge of Yellowstone National Park in Wyoming. According to a press release from the University of Utah, the quake was felt throughout the national park as well as in the nearby towns of West Yellowstone and Gardiner. On the USGS website, only 97 people reported feeling the quake, though the number that actually felt it is likely much higher. So far, there are no reports of damage, which is not surprising given the quake’s magnitude, which only registered light shaking near the epicenter, based on the USGS ShakeMap.

    2
    This Temblor map shows the location of yesterday’s M=4.4 earthquake in the western part of Yellowstone National Park. This earthquake is part of a larger swarm, which began on June 12. Also in this figure is the location of the 1959 M=7.3 Hebgen Lake earthquake.

    According to the University of Utah, this M=4.4 earthquake is part of a swarm that began on June 12, that has included 30 M=2+ earthquakes, and four M=3+ earthquakes, including the one yesterday. They also point out that swarms like this are extremely common in the Yellowstone region, and comprise approximately 50% of the seismicity. While there are mapped faults around the location of this active swarm, based on the northwest trend in the seismicity, and a focal mechanism produced by Bob Herrmann of St. Louis University, this quake appears to have occurred on a left-lateral strike-slip fault which connects the east-west-trending extensional faults in the region. It should also be pointed out that this M=4.4 quake is the largest to strike the area since 2014, when there was a M=4.8.

    Seismic activity around Yellowstone is extremely common and is caused by a variety of factors. Some of the smaller earthquakes are a result of rising and moving magma beneath the surface. However, Yellowstone is unlikely to experience a large earthquake because the hot magma beneath the surface causes the bedrock to behave more ductile, meaning it is less likely to rupture. While large earthquakes within the park are unlikely, the region is highly sensitive to remote earthquakes. What this means is that seismic waves from earthquakes hundreds of kilometers away can slightly destabilize the volcanic and hydrothermal systems, resulting in small earthquakes and hydrothermal eruptions.

    The area around today’s small-moderate earthquake is also of interest as it is only 15-20 km from the epicenter of the 1959 M=7.3 Hebgen Lake earthquake. This earthquake killed 28 people and resulted in millions of dollars worth of damage. The majority of these fatalities were the result of a massive landslide triggered by the shaking. Therefore, while rare, large earthquakes can occur just outside of Yellowstone. Based on the Global Earthquake Activity Rate (GEAR) model, which is available in Temblor we can see that yesterday’s M=4.4 earthquake in Yellowstone should not be considered surprising, given the region is susceptible to M=5.25+ quakes. This model uses seismicity since 1977 and global strain rates to forecast what the likely earthquake magnitude is in your lifetime anywhere on earth. What we can also see from this model is that the M=7.2 Hebgen Lake earthquake just to the west of yesterday’s shock was an extremely rare and surprising event. Should the characteristics of this ongoing swarm in Yellowstone National Park change, we will update this post.

    3
    This Temblor map shows the Global Earthquake Activity Rate (GEAR) model for the area around Yellowstone National Park. What is evident from this map is that the M=4.4 earthquake should not be considered surprising, given the area is susceptible to M=5.25+ quakes. The GEAR model uses seismicity since 1977 and global strain rates to forecast the likely earthquake magnitude in your lifetime anywhere on earth.

    References
    University of Utah Seismograph Stations
    USGS
    Bob Herrmann (St. Louis University)
    Robert B. Smith (University of Utah)
    Jamie Mark Farrell (University of Utah)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    You can help many citizen scientists in detecting earthquakes and getting the data to emergency services people in affected area.
    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    BOINCLarge

    BOINC WallPaper

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

     
  • richardmitnick 11:54 am on June 13, 2017 Permalink | Reply
    Tags: , Archeology, , , Geology, Megafauna, Naracoorte where half a million years of biodiversity and climate history are trapped in caves, University of Adelaide   

    From COSMOS: “Naracoorte, where half a million years of biodiversity and climate history are trapped in caves” 

    Cosmos Magazine bloc

    COSMOS

    13 June 2017
    Liz Reed, Research Fellow, University of Adelaide
    Lee Arnold, ARC Future Fellow, University of Adelaide

    1
    Enormous sediment cones in a cave at Naracoorte. Two people in overalls show the scale of the area. Steven Bourne, Author provided

    In 1857, guided by the flickering light of a candle deep in a cave at Naracoorte in South Australia, the Reverend Julian Tenison-Woods stumbled across thousands of tiny bones of rodents and small marsupials buried at the base of crystal columns.

    Without knowing it, Woods had found a time machine of sorts – a record of biodiversity and environment spanning more than half a million years.

    Now Naracoorte Caves are known as one of the world’s best fossil sites, a place where marsupial lions, enormous kangaroos and giant monitor lizards met their deaths and were preserved by layers of sand.

    But the caves captured more than just giants. Clues to Naracoorte’s past environment are also preserved in plant fossils, sediments and calcite formations.

    Big marsupials with bite: Australia’s megafauna

    Global scientific attention first focused on Naracoorte after 1969, when cave explorers entered relatively inaccessible limestone chambers. After squeezing their way through an impossibly tight gap in Victoria Cave, they discovered the palaeontological equivalent of King Tutankhamen’s tomb.

    Scattered across the red sediment floor of a vast chamber were countless skulls and jaws of Australia’s lost giants, the megafauna.

    2
    Pitfall megafauna fossil assemblage in the Upper Ossuary, Victoria Fossil Cave Naracoorte. Steven Bourne, Author provided

    The find created a buzz worldwide and set the stage for a scientific journey of discovery that has unfolded over the past four decades.

    Preserved within the deposits are fossils from a suite of megafauna species including heavyweight plant eaters such as Zygomaturus trilobus, short-faced leaf-eating kangaroos such as Procoptodon goliah, and the five-metre snake Wonambi naracoortensis. The most famous of these is the marsupial lion Thylacoleo carnifex. The most spectacular fossils from this king of the Pleistocene forests have come from Naracoorte.

    The reign of these amazing animals came to an end around 45,000 years ago, with the precise cause for their extinction still a hot topic for debate.

    3
    Fossilised skull from Thylacoleo- a carnivorous marsupial that lived in Australia around 50,000-1.5 million years ago. Steven Bourne, Author provided

    How the underground archives formed

    The Naracoorte Caves formed around one million years ago within the Gambier Limestone, itself dated to around 37 million to 12 million years old and formed during the late Eocene or Miocene epochs.

    Overlying the limestone, a series of ancient sand dunes preserve records of the changing coastline over the past few million years.

    Over time, holes opened up in the limestone, connecting the caves to the land surface. Sand and soil was transported into these cave entrances by water and wind, forming deep layered deposits spanning at least the last 500,000 years of the Quaternary period (2.6 million years to present).

    4
    Deep, layered fossil deposits in Blanche Cave, Naracoorte. Each layer represents a window in time. The tags mark individual layers. Steven Bourne, Author provided

    At the same time as the sediments were deposited, many types of animals lived in the landscape surrounding the caves. The remains of these animals accumulated in the caves and became buried and preserved in the sediment layers.

    Some species, such as bats and possums, lived and died in the caves. Predators used the caves as roosts and dens, leaving behind the bones of their prey. Owls accumulated vast deposits of small vertebrates, such as the ones discovered by Woods in 1857.

    Larger species fell victim to concealed cave entrances that acted as pitfall traps for the unwary. Kangaroos were particularly susceptible to entrapment, being fast-moving and active at night, dusk or dawn. Even the gigantic megafauna species succumbed to these traps.

    With all of these ways for animals to accumulate, it is unsurprising that the caves preserve many deposits and tens of thousands of individual animals.

    Why are these deposits so significant?

    The fossil deposits preserve diverse vertebrate species, including more than 135 different examples of amphibians, reptiles, birds and mammals.

    Nearly 20 species of megafauna are preserved, including nine species of extinct kangaroos. The preservation of the fossils is exceptional, with the finest details retained.

    Naracoorte’s record is relatively young geologically (around 500,000 years to less than 1,000 years before now), making it representative of modern ecosystems. This is why it offers value in addressing questions relevant to present and future conservation such as extinctions and adaptation to climate change and human impacts.

    Unlike most localities where single sites are preserved, the Naracoorte Caves have multiple sites in many adjacent caves. This provides a unique opportunity to compare and correlate observations across related sites over a long, continuous time span.

    5
    It’s a little bit squeezy in here. A film crew working with researchers at Naracoorte Caves. Steven Bourne, Author provided

    Recent research has revealed that the deposits contain much more than bones, with fossil plant material, pollen, fossilised algae and even DNA. This allows scientists to build a comprehensive picture of the environment during this time period. It is this incredible wealth of preserved materials that makes Naracoorte stand out.

    Associated calcite formations (such as stalagmites) have preserved critical information on past climate. For example, past rainfall can be determined by studying the fine growth layers within the formations.

    6
    Alexandra Cave, Naracoorte Caves National Park. Steven Bourne, Author provided

    World heritage significance

    International recognition came to Naracoorte in December 1994, when the caves were World Heritage listed as part of the Australian Fossil Mammal Sites (along with Riversleigh in northwestern Queensland).

    The fossil records of Naracoorte and Riversleigh reveal the evolutionary history of Australia’s unique mammals over much of the past 25 million years. The Naracoorte deposits encompass the latter part of this record, covering important events such as megafauna extinction and the arrival of humans in Australia.

    The caves are managed by the South Australian government, which oversees tourism, conservation and research. The park is an established visitor attraction, and vital to the economy and culture of the Naracoorte district. The caves add to the wealth of other geological attractions in the Limestone Coast region, including volcanoes and some of the world’s largest sinkholes.

    Moving forwards, new funding has just been announced on a project to establish benchmark data on past ecological and environmental change that is trapped in the structures at Naracoorte Caves. Working with colleagues at University of Adelaide and other Australian universities, museums, government and industry partners, we expect our next phase of research will have applications for biodiversity conservation, climate change, and building capacity for regional communities to share the stories of their unique heritage.

    7
    Large roof window entrance in the spectacular Blanche Cave, Naracoorte. It is in this cave that the first fossil bones were discovered by Woods in 1857. Steven Bourne, Author provided

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 7:30 am on May 25, 2017 Permalink | Reply
    Tags: , , Geology, IDEAS.TED.COM, The amazing world that scientists are uncovering beneath the Earth’s crust   

    From IDEAS.TED.COM: “The amazing world that scientists are uncovering beneath the Earth’s crust” 

    1

    IDEAS.TED.COM

    May 24, 2017
    Hailey Reissman

    There are continents to explore right below our feet — including two giant blobs 100 times as tall as Everest. Here’s how seismologist and geophysicist Ed Garnero is studying this unseen and largely uncharted territory.

    For most people, everything they know about the composition of the Earth is what they were taught in elementary school: that our planet is made up of an eggshell-like crust over a thick mantle surrounding a super-hot core. In the last decade, scientists have made some super-interesting — and even strange or profound — discoveries that can add detail to that picture. Among their recent subterranean findings are a river of liquid metal that moves more swiftly than the tectonic plates, “bubbles” at the crust-mantle boundary, a new species of mineral that is somehow capable of holding water hundreds of miles within the mantle, chambers of magma where rocks are heating up like popcorn and expelled.

    3
    A visualization of the seismic waves from six Gulf of California earthquake events, over the years of 2007 to 2013, created by a team led by Manochehr Bahavar of the IRIS Data Management Center.

    Like the deep oceans, our planet’s innards are extremely difficult to study. Since humans can’t travel very far into the Earth (and certainly not the 3,963 miles to its core), investigation has largely depended upon the development of technology that can sense what lies below. The existence of tectonic plates was confirmed only around fifty years ago when sonar was used to map the ocean floor. Why is venturing below so difficult? For starters, the pressure. Just eight miles down, you’d feel the equivalent of 131 elephants of force pressing down on your head. And it’s unbearably hot. The temperature at the bottom of the top layer of the crust is roughly 1,600 degrees Fahrenheit. That’s breezy compared to the Earth’s core, which is thought to be about 10,800 degrees (as hot as the surface of the sun). So far, the farthest down that humans have tunneled is 7.6 miles.

    4
    Scientists have found two enormous, mysterious blobs of super-hot material that lie under the earth’s crust. In this visualization, seismic wave paths are shown passing through the blob. The blue and red features represent, respectively, high- and low-velocity material, discovered from tomography. Visualization by Ed Garnero.

    Geophysicists use seismometers to “see” inside the Earth, similar to how X-rays see inside our bodies. We tend to think of the Earth as fairly solid, except perhaps when hit by an earthquake. In reality, though, we live on chunks of crust that are constantly doing a dance that we can’t feel but scientists are always monitoring. For example, Phoenix, Arizona, rises and falls by about 40 centimeters twice a day, due to the sun’s and moon’s gravitational pulls. And Southern California has about 10,000 earthquakes a year, most a magnitude two or less. Each of these quakes — and every rise and fall — creates seismic waves that are recorded by instruments called seismometers. Like an X-ray machine, a seismometer assesses how energy moves through an object to infer what’s happening inside that object. Right now, the Global Seismographic Network (GSN) has more than 150 seismic stations distributed throughout the world, while the Incorporated Research Institutions for Seismology (IRIS) network includes over 250 stations.

    In 2016, Ed Garnero from Arizona State University’s School of Earth & Space Exploration (TEDxManhattanBeach talk: An amazing look into the center of the earth) and a team used this trove of seismological data to delve into an ongoing mantle mystery. For decades, geophysicists had observed seismic waves slowing down in two areas beneath the crust on roughly opposite sides of the Earth: one below the Pacific Ocean and the other below Africa. They discerned that the masses were huge — each the size of a continent, 100 times the height of Mount Everest, and around 1,800 miles beneath the surface. And they assumed the areas were extra-warm, since unusually hot zones can cause waves to slow down. Garnero and his researchers were determined to find out more. “They are the largest parts of our Earth that we [have identified but] know nothing about,” he says.

    Garnero’s team looked at the data — and made a major discovery. The giant blobs are not just a different temperature from the rest of the mantle; the researchers think they have a distinctly different chemical composition too. “We see from the seismic waves that go near the boundaries of the blobs that they split into a wave that goes into the blob and slows down, while a wave that continues along the blobs’ outside margin goes at normal speed,” Garnero says. “Scientists believe temperature alone cannot do that, so the blobs being compositionally distinct is the easiest explanation.” Researchers don’t know what the blobs are made of — yet — but they can tell the masses are denser and more stable than what’s around them. And they’re most likely feeding volcanoes. “On Earth above the blobs, there are volcanoes past and present, from small to massive,” Garnero says. For example, the hotspots that formed Hawaii, Samoa and Iceland are all fed by extremely deep plumes of magma that appear to be connected to the blobs.

    Which leads to the question: Where did these blobs come from? One intriguing theory is that they’re leftovers from our planet’s formation — remnants of some primordial layer of the Earth that eroded away over billions of years through the power of convection. “Our core ‘cooks’ the mantle rock, which makes up about half of the Earth, from below, causing it to slowly turn and move,” Garnero says. “If you did a timelapse of millions of years of Earth’s rocky mantle, you’d see it swirl around just like smoke moving around a bonfire.” And perhaps some of the material was swirled into forming the continent-sized blobs. Garnero and his team have used the seismic data to construct intriguing images of the Earth that include the mantle blobs, essentially giving us an MRI of our planet.

    5
    Inside the Earth’s mantle, heat from the core (in red) cooks the mantle rock (in blue), causing the rock to move like smoke around a bonfire. The motions visualized here would happen over a few million years. Visualization by Dr. Allen K. McNamara of Arizona State University.

    Garnero wants to share with the public the thrill of searching inside the Earth. Recently, he and a group of artists from Arizona State University, led by Lance Gharavi, created Beneath: a journey within, a film-music-dance performance designed to immerse the public in seismic data. Garnero says the cross-disciplinary collaboration has been exhilarating: “The scientists give the artists a platform to create, and then the artists give the scientists a new way to see their data.” The performance, which featured artists including a bass-playing geophysicist interacting with his data through trip-hop bass-lines and a belly-dancing theoretical astrophysicist embodying seismic waves, is being held inside a 3D theater on campus.

    Next for geophysicists: Combing through data from the world’s seismometers to add to the expanding pool of subterranean knowledge. In 2017, an extremely detailed map of the inner Earth was created by a team from Princeton University with the help of one of the world’s fastest supercomputers, Titan, which can perform over 20 quadrillion calculations per second.

    ORNL Cray XK7 Titan Supercomputer

    6
    This visualization provides another view of the two continent-sized blobs of unknown material, deep within the Earth. Created by geophysicists Scott W. French and Barbara Romanowicz of the Physique du Globe and the Collège de France and UC Berkeley.

    As for Garnero, his ambitions are galactic. He and his students are now working “to get the most detailed information out of seismic data,” he says, including revisiting an earlier study of the moon that confirmed it has a solid, iron-rich core. His department is also developing a tiny seismometer for NASA to take on a mission to Jupiter’s moon Europa; it would measure tremors on Europa’s crust and possibly locate as-yet-undiscovered bodies of water beneath its icy exterior. Designing such a device is not easy, according to Garnero. Seismometers are ultra-sensitive pieces of equipment, and this machine would need to be sturdy enough to handle a rough spacecraft landing and the other extremes that come with extraterrestrial travel.

    The key to future discoveries, either here on or on other spheres, lies in increasing the variety, amount and sensitivity of seismometers. “The more sensors we have, the more we study things like the blobs, and the more other things we can see,” Garnero says. “That’s good for me because that means there are more things to discover.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
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