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  • richardmitnick 8:16 am on March 22, 2019 Permalink | Reply
    Tags: ARC-Australian Research Council, , , Geology   

    From Curtin University: “New ARC-funded research uses new tool to examine world’s oldest rocks” 

    From Curtin University

    19 March 2019

    Yasmine Phillips
    Media Relations Manager, Public Relations
    Tel: +61 8 9266 9085
    Mob: +61 401 103 877
    yasmine.phillips@curtin.edu.au

    Curtin University researchers will develop a new fingerprinting tool capable of delving deeper into the Earth’s rock layers, in what promises to be an important development for Australia’s mining and petroleum sectors.

    The research will enhance industry’s understanding of the Earth’s sedimentary rocks by investigating case studies at the Yilgarn Craton, Australia’s premier gold and nickel province spanning from Meekatharra to WA’s South-West including Kalgoorlie, as well as the Canning Basin, located in the Kimberley, and the Northern Carnarvon Basin.

    The project secured $352,000 from the Australian Research Council’s Linkage Project scheme as part of the latest funding announcement made by the Federal Minister for Education, the Hon. Dan Tehan, today.

    Curtin University Acting Deputy Vice-Chancellor Research Professor Garry Allison said the research had potentially important implications for the mining and petroleum sectors.

    “Western Australia’s mineral and petroleum exports are major contributors to the Australian economy, but in recent years the number of significant discoveries has fallen and those that have been identified tend to be at greater depths,” Professor Allison said.

    “This new research will develop a new fingerprinting tool capable of shedding more light on some of the world’s oldest rocks with the aim of helping Australian mining and petroleum explorers to uncover major new mineral and hydrocarbon deposits.”

    The state-wide isotope-based research project will be led by Associate Professor Chris Kirkland and Professor Chris Elders, both from the School of Earth and Planetary Sciences at Curtin University.

    Curtin University researchers will work with Northern Star Resources and the Geological Survey of Western Australia, within the Department of Mines, Industry Regulation and Safety, on the project.

    As part of the latest round of ARC grants announced today, Curtin University researchers will also work on an international project, led by The University of Western Australia, that will test and review the success of teaching Einstein’s theories of space, time, matter, light and gravity. That project was awarded $898,560 in ARC funding.

    See the full article here .

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    Curtin University (formerly known as Curtin University of Technology and Western Australian Institute of Technology) is an Australian public research university based in Bentley and Perth, Western Australia. The university is named after the 14th Prime Minister of Australia, John Curtin, and is the largest university in Western Australia, with over 58,000 students (as of 2016).

    Curtin was conferred university status after legislation was passed by the Parliament of Western Australia in 1986. Since then, the university has been expanding its presence and has campuses in Singapore, Malaysia, Dubai and Mauritius. It has ties with 90 exchange universities in 20 countries. The University comprises five main faculties with over 95 specialists centres. The University formerly had a Sydney campus between 2005 & 2016. On 17 September 2015, Curtin University Council made a decision to close its Sydney campus by early 2017.

    Curtin University is a member of Australian Technology Network (ATN), and is active in research in a range of academic and practical fields, including Resources and Energy (e.g., petroleum gas), Information and Communication, Health, Ageing and Well-being (Public Health), Communities and Changing Environments, Growth and Prosperity and Creative Writing.

    It is the only Western Australian university to produce a PhD recipient of the AINSE gold medal, which is the highest recognition for PhD-level research excellence in Australia and New Zealand.

    Curtin has become active in research and partnerships overseas, particularly in mainland China. It is involved in a number of business, management, and research projects, particularly in supercomputing, where the university participates in a tri-continental array with nodes in Perth, Beijing, and Edinburgh. Western Australia has become an important exporter of minerals, petroleum and natural gas. The Chinese Premier Wen Jiabao visited the Woodside-funded hydrocarbon research facility during his visit to Australia in 2005.
    Contents

     
  • richardmitnick 5:25 pm on March 13, 2019 Permalink | Reply
    Tags: , , , Comet, Controversial from the time it was proposed the hypothesis even now continues to be contested by those who prefer to attribute the end-Pleistocene reversal in warming entirely to terrestrial causes., , Geology, Kennett and fellow stalwarts of the Younger Dryas Boundary (YDB) Impact Hypothesis have recently received a major boost:, , The discovery of a very young 31-kilometer-wide impact crater beneath the Greenland ice sheet which they believe may have been one of the many comet fragments that impacted Earth at the onset of the Y, The layer containing these spherules also show peak concentrations of platinum and gold and native iron particles rarely found in nature, The Pilauco dig site in a suburb of the Osorno province in Chile, The presence of microscopic spherules interpreted to have been formed by melting due to the extremely high temperatures associated with impact, They believe this may have been one of the many comet fragments that impacted Earth at the onset of the Younger Dryas., UC Santa Barbara geology professor emeritus James Kennett, , Younger Dryas Impact Hypothesis   

    From UC Santa Barbara: “The Day the World Burned” 

    UC Santa Barbara Name bloc
    From UC Santa Barbara

    March 8, 2019
    Sonia Fernandez

    1
    2
    The researchers found evidence of cosmic impact at the Pilauco dig site in a suburb of the Osorno province in Chile. Photo Credit: Courtesy Image

    When UC Santa Barbara geology professor emeritus James Kennett and colleagues set out years ago to examine signs of a major cosmic impact that occurred toward the end of the Pleistocene epoch, little did they know just how far-reaching the projected climatic effect would be.

    3
    James Kennett. Photo Credit: Sonia Fernandez

    “It’s much more extreme than I ever thought when I started this work,” Kennett noted. “The more work that has been done, the more extreme it seems.”

    He’s talking about the Younger Dryas Impact Hypothesis, which postulates that a fragmented comet slammed into the Earth close to 12,800 years ago, causing rapid climatic changes, megafaunal extinctions, sudden human population decrease and cultural shifts and widespread wildfires (biomass burning). The hypothesis suggests a possible triggering mechanism for the abrupt changes in climate at that time, in particular a rapid cooling in the Northern Hemisphere, called the Younger Dryas, amid a general global trend of natural warming and ice sheet melting evidenced by changes in the fossil and sediment record.

    Controversial from the time it was proposed, the hypothesis even now continues to be contested by those who prefer to attribute the end-Pleistocene reversal in warming entirely to terrestrial causes. But Kennett and fellow stalwarts of the Younger Dryas Boundary (YDB) Impact Hypothesis, as it is also known, have recently received a major boost: the discovery of a very young, 31-kilometer-wide impact crater beneath the Greenland ice sheet, which they believe may have been one of the many comet fragments that impacted Earth at the onset of the Younger Dryas.

    Now, in a paper published in the journal Nature Scientific Reports, Kennett and colleagues, led by Chilean paleontologist Mario Pino, present further evidence of a cosmic impact, this time far south of the equator, that likely lead to biomass burning, climate change and megafaunal extinctions nearly 13,000 years ago.

    “We have identified the YDB layer at high latitudes in the Southern Hemisphere at near 41 degrees south, close to the tip of South America,” Kennett said. This is a major expansion of the extent of the YDB event.” The vast majority of evidence to date, he added, has been found in the Northern Hemisphere.

    This discovery began several years ago, according to Kennett, when a group of Chilean scientists studying sediment layers at a well-known Quaternary paleontological and archaeological site, Pilauco Bajo, recognized changes known to be associated with YDB impact event. They included a “black mat” layer, 12,800 years in age, that coincided with the disappearance of South American Pleistocene megafauna fossils, an abrupt shift in regional vegetation and a disappearance of human artifacts.

    “Because the sequencing of these events looked like what had already been described in the YDB papers for North America and Western Europe, the group decided to run analyses of impact-related proxies in search of the YDB layer,” Kennett said. This yielded the presence of microscopic spherules interpreted to have been formed by melting due to the extremely high temperatures associated with impact. The layer containing these spherules also show peak concentrations of platinum and gold, and native iron particles rarely found in nature.

    “Among the most important spherules are those that are chromium-rich,” Kennett explained. The Pilauco site spherules contain an unusual level of chromium, an element not found in Northern Hemisphere YDB impact spherules, but in South America. “It turns out that volcanic rocks in the southern Andes can be rich in chromium, and these rocks provided a local source for this chromium,” he added. “Thus, the cometary objects must have hit South America as well.”

    Other evidence, which, Kennett noted, is consistent with previous and ongoing documentation of the region by Chilean scientists, pointed to a “very large environmental disruption at about 40 degrees south.” These included a large biomass burning event evidenced by, among other things, micro-charcoal and signs of burning in pollen samples collected at the impact layer. “It’s by far the biggest burn event in this region we see in the record that spans thousands of years,” Kennett said. Furthermore, he went on, the burning coincides with the timing of major YDB-related burning events in North America and western Europe.

    The sedimentary layers at Pilauco contain a valuable record of pollen and seeds that show change in character of regional vegetation — evidence of a shifting climate. However, in contrast to the Northern Hemisphere, where conditions became colder and wetter at the onset of the Younger Dryas, the opposite occurred in the Southern Hemisphere.

    “The plant assemblages indicate that there was an abrupt and major shift in the vegetation from wet, cold conditions at Pilauco to warm, dry conditions,” Kennett said. According to him, the atmospheric zonal climatic belts shifted “like a seesaw,” with a synergistic mechanism, bringing warming to the Southern Hemisphere even as the Northern Hemisphere experienced cooling and expanding sea ice. The rapidity — within a few years — with which the climate shifted is best attributed to impact-related shifts in atmospheric systems, rather than to the slower oceanic processes, Kennett said.

    Meanwhile, the impact with its associated major environmental effects, including burning, is thought to have contributed to the extinction of local South American Pleistocene megafauna — including giant ground sloths, sabretooth cats, mammoths and elephant-like gomphotheres — as well as the termination of the culture similar to the Clovis culture in the north, he added. The amount of bones, artifacts and megafauna-associated fungi that were relatively abundant in the soil at the Pilauco site declined precipitously at the impact layer, indicating a major local disruption.

    The distance of this recently identified YDB site — about 6,000 kilometers from the closest well-studied site in South America — and its correlation with the many Northern Hemispheric sites “greatly expands the extent of the YDB impact event,” Kennett said. The sedimentary and paleo-vegetative evidence gathered at the Pilauco site is in line with previous, separate studies conducted by Chilean scientists that indicate a widespread burn and sudden major climate shifts in the region at about YDB onset. This new study further bolsters the hypothesis that a cosmic impact triggered the atmospheric and oceanic conditions of the Younger Dryas, he said.

    “This is further evidence that the Younger Dryas climatic onset is an extreme global event, with major consequences on the animal life and the human life at the time,” Kennett said. “And this Pilauco section is consistent with that.”

    Research on this study was also conducted by Ana Abarzúa, Giselle Astorga, Alejandra Martel-Cea, Nathalie Cossio, Maria Paz Lira and Rafael Labarca of Universidad Austral de Chile; R. Ximena Navarro of Universidad Católica de Temuco; and Malcolm A. LeCompte and Victor Adedeji of Elizabeth City State University. Christopher Moore of University of South Carolina; Ted E. Bunch and Charles Mooney of Northern Arizona University; and Wendy S. Wolbach of DePaul University contributed research, as did Allen West of Comet Research Group.

    See the full article here .


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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 7:38 am on March 13, 2019 Permalink | Reply
    Tags: "Old stone walls record the changing location of magnetic North", , , Geology, Geomagnetism,   

    From The Conversation: “Old stone walls record the changing location of magnetic North” 

    Conversation
    From The Conversation

    March 12, 2019
    John Delano

    1
    The orientations of the stone walls that crisscross the Northeastern U.S. can tell a geomagnetic tale as well as a historical one. John Delano, CC BY-ND

    When I was a kid living in southern New Hampshire, my family home was on the site of an abandoned farmstead consisting of massive stone foundations of quarried granite where dwellings once stood. Stone walls snaked throughout the forest. As I explored the deep woods of tall oaks and maples, I wondered about who had built these walls, and why. What stories did these walls contain?

    Decades later, while living in a rural setting in upstate New York and approaching retirement as a geologist, my long dormant interest was rekindled by treks through the neighboring woods. By now I knew that stone walls in New England and New York are iconic vestiges from a time when farmers, in order to plant crops and graze livestock, needed to clear the land of stones. Tons and tons of granite had been deposited throughout the region during the last glaciation that ended about 10,000 years ago.

    By the late 1800s, nearly 170,000 subsistence farming families had built an estimated 246,000 miles of stone walls across the Northeast. But by then, the Industrial Revolution had already started to contribute to the widespread abandonment of these farms in the northeastern United States. They were overgrown by forests within a few decades.

    During my more recent walks through the woods, on a whim I used a hand-held GPS unit to map several miles of stone walls. And that was how I realized that in addition to being part of an American legacy, their locations record a centuries-long history of the Earth’s wandering magnetic field.

    Connecting the walls with historical maps

    The complex array of walls that emerged from my GPS readings made no sense to me until I found an old map of my town’s property boundaries at the local historical society. Suddenly I saw that some of the stone walls on my map lay along property lines from 1790. They marked boundaries.

    My subsequent searches of church records and decades of the federal census revealed the names of these farm families and details of their lives, including annual yields from their harvests. I started to feel like the stone walls were letting me connect with the long-gone folks who had worked this land.

    Now the wheels in my scientist’s mind really started spinning. Did the original land surveys from the 18th and 19th centuries in this part of town still exist? What were the magnetic compass-bearings of those boundaries on the original surveys?

    2
    Historical maps and surveys underscore the orderly way plots were divvied up from the landscape in a grid. Charles Peirce/Stoddard, New Hampshire

    I knew that the location of magnetic north drifts over time due to changes in the Earth’s core. Could I determine its drift using stone walls and the old land surveys? My preliminary map of stone walls and a few historical surveys showed that the approach had potential.

    To have any scientific value, though, this work had to encompass much larger areas. I needed a different strategy for finding and mapping stone walls. Luckily I found two troves of useful information. First, the New York State Archives had hundreds of the original land surveys from the 18th and 19th centuries. And secondly, airborne LiDAR (light detection and ranging) images were publicly available that could reveal stone walls hidden beneath the forest canopy over much larger areas than I could cover on my own by foot.

    3
    Magnetic north and geographic north aren’t the same – and their difference changes over time. Siberian Art/Shutterstock.com

    Tracking magnetic north’s drift over time

    The Earth rotates on its axis once every 24 hours. The location of that spin axis in the Northern Hemisphere is called true north, and wanders very slowly. The location of true north can be considered stationary, though, on a timescale of a few centuries.

    But that’s not where a compass aims when it points north. The location of the north magnetic pole is not only at a different location from true north, but also changes rapidly – currently about one degree per 10 years in New England.

    The difference in direction between true north and magnetic north (at a specific time and location on the Earth) is known as the magnetic declination. Global information about historic variations in magnetic declination is currently based on thousands of magnetic compass-bearings recorded in ships’ navigational logs from 1590 onwards.

    But now my work on 726 miles of stone walls provides an independent check [JGR Solid Earth] on magnetic declination between 1685 and 1910.

    Here’s the logic. When settlers were piling up those stones along the boundaries of their plots, they were using property lines that had been laid out according to the surveyors’ compass readings. Using LiDAR images, the bearings of those stone walls could be determined with respect to true north and compared with the surveyors’ magnetic bearings. The difference is the magnetic declination at the time of the original survey.

    For example, the original surveys divided New Hampshire’s Stoddard township into hundreds of lots with boundaries with magnetic compass-bearings of N80 degrees W and N14 degrees E in 1768. As the land was cleared for farming, owners built stone walls along and within those 1768 surveyed boundaries.

    4
    Lidar reveals the stone walls hidden beneath the canopy. Comparing their orientation with true north provides the magnetic declination at this location when boundaries were surveyed in 1768. CC BY-ND

    Now one can compare the bearings of those stone wall-defined boundaries relative to magnetic north and true north today. The difference shows that the magnetic declination at this location in 1768 was 7.6 ± 0.3 degrees W. That’s a good match for scientists’ current geophysical model. Since the magnetic declination at this location today is 14.2 degrees W, the direction to magnetic north at this location has moved about 6.6 degrees further west since 1768.

    Data from these stone walls strengthen the current geophysical model about the Earth’s magnetic field.

    See the full article here .

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    The Conversation launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 11:15 am on March 12, 2019 Permalink | Reply
    Tags: "Scientists Track Deep History of Planets' Motions and Effects on Earth's Climate", , , , , Geology, Paleogeology   

    From Columbia University: “Scientists Track Deep History of Planets’ Motions, and Effects on Earth’s Climate” 

    Columbia U bloc

    From Columbia University

    March 4, 2019
    Kevin Krajick

    Newly Forming Map of Chaos in the Solar System.

    1
    Geologist Paul Olsen at Arizona’s Petrified Forest National Park, where 200 million-year-old rocks are helping reveal the long-ago motions of other planets. (Kevin Krajick/Earth Institute)

    Scientists have long posited that periodic swings in Earth’s climate are driven by cyclic changes in the distribution of sunlight reaching our surface. This is due to cyclic changes in how our planet spins on its axis, the ellipticity of its orbit, and its orientation toward the sun — overlapping cycles caused by subtle gravitational interplays with other planets, as the bodies whirl around the sun and by each other like gyrating hula-hoops.

    But planetary paths change over time, and that can change the cycles’ lengths. This has made it challenging for scientists to untangle what drove many ancient climate shifts. And the problem gets ever more difficult the further back in time you go; tiny changes in one planet’s motion may knock others’ askew — at first slightly, but as eons pass, these changes resonate against each other, and the system morphs in ways impossible to predict using even the most advanced math. In other words, it’s chaos out there. Up to now, researchers are able to calculate the relative motions of the planets and their possible effects on our climate with reasonable reliability back only about 60 million years — a relative eyeblink in the 4.5 billion-plus life of Earth.

    This week, in a new paper in the Proceedings of the National Academy of Sciences, a team of researchers has pushed the record way back, identifying key aspects of the planets’ motions from a period around 200 million years ago. The team is led by geologist and paleontologist Paul Olsen of Columbia University’s Lamont-Doherty Earth Observatory. Last year, by comparing periodic changes in ancient sediments drilled from Arizona and New Jersey, Olsen and colleagues identified a 405,000-year cycle in Earth’s orbit that apparently has not changed at all over at least the last 200 million years — a kind of metronome against which all other cycles can be measured. Using those same sediments in the new paper, they now have identified a cycle that started out lasting 1.75 million years, but is now operating every 2.4 million years. This, they say, allows them to extrapolate long-term changes in the paths of Jupiter and the inner planets (Mercury, Venus and Mars), the bodies most likely to affect our own orbit.

    Olsen’s ultimate aim: to use Earth’s rocks to create what he calls a “Geological Orrery” — a record of climatic changes on Earth that can be extrapolated back into a larger map of solar system motions over hundreds of millions of years. He says it would open a window not just onto our own climate, but the evolution of the solar system itself, including the possible existence of past planets, and its possible interactions with invisible dark matter.

    We spoke with Olsen about the Geological Orrery, his work, and the new paper.

    Most people have probably never even heard the word “orrery.” What is it, and how does it fit with our evolving understanding of celestial mechanics?

    In the early 1800s, mathematician Pierre-Simon de Laplace took Newton’s laws of gravitation and planetary motion and published his idea that it should be possible to develop a single great equation that would allow all the universe to be modeled. With only knowledge of the present, all the past and future could be known. This idea is embodied in the orrery, a mechanical model of the solar system. Clockwork mechanisms like this for predicting eclipses and the like go back to the ancient Greeks, but it’s now clear the problem is far more complicated, and interesting.

    We’ve since discovered that the solar system not a clockwork. It is in fact chaotic over long time scales, so Laplace’s grand equation was a mirage. This means you cannot unpack its history from calculations or models, no matter how precise, because the motions of the real solar system are incredibly sensitive. Varying any factor even a tiniest bit results in a different outcome after millions of years — even what the major asteroids, or minor planets, such as Ceres and Vesta, are doing. One of my coauthors, Jacques Laskar, has shown that computations can project forward or backward only 60 million years. After that, the predictions become utterly unreliable. Since Earth is about 4.6 billion years old, this means that only about 1.6 percent of its past or future orbit can be predicted. Over billions of years, the best calculations reveal many possible terrific events, such as one of the inner planets falling into the sun or being ejected from the solar system. Maybe even that Earth and Venus could collide one day. We can’t tell if any of these actually happened, or might happen in the future. So we need some other method to limit the possibilities.

    2
    View looking east toward the U.S. East Coast, Oct. 7, 2015, when the three planets most influential to Earth’s orbit lined up with the Moon. Lower left near Earth’s horizon, Jupiter (greenish); slightly higher, Mars (reddish); slightly higher and to right, Venus (bright white); and the Moon. On Earth’s surface, lights of the New York-Philadelphia metro region trace the area where scientists took rock cores revealing these planets’ motions. Inspired by a photo taken by U.S. astronaut Scott Kelly. (Painting by Paul Olsen; acrylic on clay board, digitally modified)

    So, what is the “Geological Orrery?” Are you trying again to boil everything down to one equation, or is this something different?

    The Geological Orrery is the opposite of an equation or model. It’s designed to provide a precise and accurate history of the solar system. We get that history right here on Earth, from the history of our climates, which is recorded in the geological record, especially in large, long-lived lakes.

    Earth’s orbit and axis orientation are constantly changing because they are being deformed by the gravitational attractions of other bodies. These changes affect the distribution of sunlight hitting our surface, which in turn affects climate, and the kinds of sediments that are deposited. That gives us the geological record of solar system behavior.

    Many scientists have used sediments to determine the effects of orbital deformations. That’s how we know that the ice ages of the last few million years were paced by them. Some researchers have tried to go back much further in time. What is new here is the systematic approach of taking rock cores spanning tens of millions of years, looking at the cyclical sedimentary record of climate and accurately dating those changes over multiple sites. That allows us to capture the full range of solar system-driven deformations of our orbit and axis over long time periods.

    3
    A mechanical orrery presented in 1713 by English inventor John Rowley to Charles Boyle, the Fourth Earl of Orrery — origin of the modern name. (Engraving from The Universal Magazine, 1749)

    What are the rocks telling you about how such cyclic changes affect our climate?

    With two major coring experiments to date, we’ve we learned that changes in tropical climates from wet to dry during the time of early dinosaurs, from about 252 to 199 million years ago, were paced by orbital cycles lasting about 20,000, 100,000 and 400,000 years. On top of that is a much longer cycle of about 1.75 million years. The shorter cycles are about the same today, but the 1.75 million year cycle is way off —it’s 2.4 million years today. We think the difference is caused by a gravitational dance between Earth and Mars. This difference is the fingerprint of solar system chaos. No existing set of models or calculations precisely duplicates these data.

    How far do you think we’re going to get with this problem during your lifetime?

    Next step is to combine our two finished coring experiments with cores taken at high latitudes. While our core data do a really good job of mapping some aspects of planetary orbits, they tell us nothing about others. For those, we need a core from an ancient lake above the paleo-Arctic or Antarctic circles. Such deposits exist in what are now China and Australia. We also would like to include deposits that extend the record up 20 million years or so towards the present, and another low-latitude core that we can precisely date. With those, we would be able to determine what if any changes have taken place in that Mars-Earth gravitational dance. That would be a full proof of concept of the Geological Orrery. I plan to certainly be around for that.

    4
    Digital elevation map of sediment strata formed on a lake bottom some 220 million years ago, near present day Flemington, N.J. The lakebed was later tilted so that its cross section now faces the sky. Purple sections are ridges — remains of hard, compressed sediments formed when climate was wet and the lake deep; alternating greenish sections are lower areas made of eroded-out softer sediments from dryer times. Each pair represents 405,000 years. Groups of ridges in lower part of image manifest a separate 1.7 million-year cycle that has today grown to 2.4 million years. Thee 40-square-mile area is dissected by parts of the modern Raritan and Neshanic rivers (blue). (LIDAR image by U.S. Geological Survey; digital colorization by Paul Olsen)

    Your paper mentions that this work might offer insights into the evolution of the solar system — maybe the even wider universe.

    If all this works out, we could plan the grand mission to use the Geological Orrery for at least the rest of the time between 60 and 190 million years age. This mission would be expensive by geology standards, because rock coring is expensive. But the results would have far-reaching implications. For sure we would have data to produce high-quality climate models for Earth. And there is no doubt we would have the parameters for past climates on Mars or other rocky planets. But more excitingly and more speculative is the possibility of exploring how we might need to tweak gravity theory, or test some controversial theories, such as the possible existence of a plane of dark matter in our galaxy that our solar system passes through periodically.

    We’re talking deep time here. Does this have any application to questions about modern-day climate change?

    It does have relevance to the present. in addition to the way climate is tuned to our orbit, it’s also affected by the amount of carbon dioxide in the air. Now we’re heading into a time when CO2 levels may be as high as they were 200 million years ago, early dinosaur times. This gives us a potential way to see how all the factors interact. It also has resonance with our search for life on Mars, or for habitable exoplanets.

    The paper is coauthored by Jacques Laskar, Observatoire de Paris; Dennis Kent and Sean Kinney, Lamont-Doherty Earth Observatory; David Reynolds, ExxonMobil Exploration; Jingeng Sha, Nanjing Institute of Geology and Paleontology; and Jessica Whiteside, University of Southampton.

    See the full article here .

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    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 11:13 am on March 5, 2019 Permalink | Reply
    Tags: "I found these unusual rocks quite by accident all those years ago. On a hunch I prepared a bunch of samples and when I enhanced the images I was genuinely surprised by what I found.", , Geology, Hiding in a slab of northern Canada's ancient sea floor geologists have uncovered a 'superhighway' of prehistoric worm tunnels, It was thought that half a billion years ago the ocean floor was completely void of life an ancient dead zone without the necessary oxygen for survival, , , Serendipity is a common aspect to my kind of research" says Pratt, Thanks to a lucky new discovery scientists are now second-guessing that assumption, The Burgess shale also located in northern Canada is famous for its remarkably preserved Cambrian fossils, The Cambrian period is known for its explosion of life with multicellular organisms developing and spreading right across the globe, The discovery was made by Brian Pratt a geologist and palaeontologist from the University of Saskatchewan 35 years after he first collected the sedimentary rocks from the Mackenzie Mountains in northw, These fossilised tunnels date back to the Cambrian period - 270 million years before the first dinosaurs, These tunnels ranged from 0.5 to 15 millimetres (0.02 to 0.6 inches) which suggests there was quite a bit of diversity in worm life at this time and in this unexpected place., University of Saskatchewan   

    From Science Alert for University of Saskatchewan: “Scientists Discover an Ancient ‘Superhighway’ at The Bottom of The Ocean” 

    ScienceAlert

    From Science Alert

    for

    1

    University of Saskatchewan

    5 MAR 2019
    CARLY CASSELLA

    2
    (University of Saskatchewan)

    Half a billion years ago, the ocean floor was thought to be completely void of life, an ancient dead zone without the necessary oxygen for survival.

    Thanks to a lucky new discovery, scientists are now second-guessing that assumption. Hiding in a slab of northern Canada’s ancient sea floor, geologists have uncovered a ‘superhighway’ of prehistoric worm tunnels.

    These fossilised tunnels date back to the Cambrian period – 270 million years before the first dinosaurs – and they suggest that even the deepest seabeds held more life, and oxygen, than we once thought.

    The discovery was made by Brian Pratt, a geologist and palaeontologist from the University of Saskatchewan, 35 years after he first collected the sedimentary rocks from the Mackenzie Mountains in northwest Canada.

    “Serendipity is a common aspect to my kind of research,” says Pratt.

    “I found these unusual rocks quite by accident all those years ago. On a hunch I prepared a bunch of samples and when I enhanced the images I was genuinely surprised by what I found.”

    The burrows where these ancient worms once used to roam were not visible until Pratt used a flatbed scanner and image editing to bring them to life.

    There, in the slices of rock, was a nice surprise: an abundance of exceptionally well-defined burrows, criss-crossing each other in every which way.

    These tunnels ranged from 0.5 to 15 millimetres (0.02 to 0.6 inches), which suggests there was quite a bit of diversity in worm life at this time and in this unexpected place.

    Some of the prehistoric worms, for instance, are estimated at no more than a millimetre, while others are thought to be as long as a finger.

    3
    (Brian Pratt, University of Saskatchewan)

    The authors think the smaller tunnels were made by polychaetes, a simple creature also known as a bristle worm. Meanwhile, the larger burrows probably belonged to predators, who liked to attack unsuspecting arthropods and other surface-dwelling worms from their hiding spot.

    The Cambrian period is known for its explosion of life, with multicellular organisms developing and spreading right across the globe. The Burgess shale, also located in northern Canada, is famous for its remarkably preserved Cambrian fossils.

    Scientists thought these fossils had been so well preserved because they’d fallen to the bottom of the sea where there was little oxygen to speed up their decay, and also fewer animals around who’d eat the evidence.

    If the new research is right and there was, in fact, life in the seafloor, we may need to rethink some of our assumptions about ancient oceans and the continental shelves they sit upon.

    “This has a lot of implications which will now need to be investigated, not just in Cambrian shales but in younger rocks as well,” says Pratt.

    “People should try the same technique to see if it reveals signs of life in their samples.”

    This study has been published in Geology.

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 12:13 pm on March 2, 2019 Permalink | Reply
    Tags: "Geologists Siege Yorktown", A first order fix would be to turn some patriotic goats loose on the English Ivy and other encroaching vegetation. After the goat platoon finishes its job it’d be reasonable to gently power wash the, , English Ivy is destroying an important natural and historic American landmark at the very site where the United States won its independence. How cheeky!, Geology, I now have a 12-year time series from our yearly trips to Cornwallis Cave. The photos illustrate that the outcrop is suffering from a number of ailments the most obvious are the festoons of English Iv, Our yearly siege of Yorktown is all about doing geology outside the classroom but with a historic twist, Something should be done to remediate this abomination, The College of William & Mary, The Yorktown Formation a widespread Pliocene marine deposit that underlies most of the Virginia Coastal Plain   

    From The College of William & Mary: “Geologists Siege Yorktown” 

    From The College of William & Mary

    March 1, 2019
    Chuck Bailey

    Yorktown’s most famous siege took place in 1781, when American and French troops surrounded General Cornwallis and the British forces. Ultimately, the British capitulated and the American Revolution was effectively won at Yorktown – it was a big deal. For more than a decade now, William & Mary geologists have repeatedly sieged Yorktown during the first field lab in the Earth Structure & Dynamics course.

    On Monday and Tuesday, we were back in Yorktown on a two-fold mission to 1) practice doing geology in the field, and 2) learn about the geology underfoot on the Atlantic Coastal Plain.

    1
    The 2019 William & Mary Earth Structure & Dynamics lab sections at Yorktown. The Monday lab at Cornwallis Cave and the Tuesday lab at the 2nd French Siege Line.

    Our first activity involves measuring a set of compass bearings, and then using a bit of trigonometry to estimate the width of the broad York River estuary. Curiously, the trigonometry typically proves to be more challenging than the compass measurements.

    2
    Top – W&M geologists at work measuring bearings to determine the width of the York River estuary (2015). Bottom Left – The challenge of measuring a bearing on a rainy day (2013). Bottom Right – This is no event! Working out the trigonometry to estimate the width of the York River (2014).

    We also descend upon a 21st century “rip-rap” revetment/breakwater. It’s an engineered structure placed along the watery edge of the beach, designed to slow shoreline erosion. These extraordinarily large blocks include a diverse suite of rocks and structures. The rip-rap was quarried from igneous and metamorphic rocks in the Piedmont and shipped by barge to the Yorktown waterfront. Perfect practice to ready ourselves for our field trip to the Appalachian Mountains in April.

    3
    Claire Rae and Gabe Mojica examining geologic structures in the rip-rap along the York River.

    From the modern shoreline defenses, we roll onward to Cornwallis Cave, a historic natural outcrop on the Virginia Coastal Plain. The cave is a manmade chamber carved out of the rock. During the siege of Yorktown, the Allied artillery shelled the British positions, and as the story goes, General Cornwallis sought shelter in this grotto. However, National Park Service research suggests the Cornwallis story to be apocryphal. During the Civil War munitions were stored here, and large square recesses were cut to support a plank roof that extended outward from the cliff. In the early 20th century, Cornwallis Cave was something of a tourist attraction.

    4
    Top Left – An ‘old school’ postcard of Cornwallis Cave from the early 20th Century. Right – Lord Cornwallis Cave in 1915, note the inclined strata evident on the cliff face. Bottom Left – A Civil War view of Federal equipment at Yorktown, the view is to the northwest, Cornwallis Cave is at the base of the bluffs in the background.

    The Coastal Plain is underlain principally by unconsolidated sediment, that is sediment which has not been cemented into rock. Thus, the exposure at Cornwallis Cave is unusual as the sediment actually holds together and is justly described as rock. It’s an indurated biofragmental sandstone, also known as coquina. The calcareous sand ranges from fine to granular and is composed primarily of fragmented bivalve shells (with an assortment of other organisms). The carbonate content in the rock is >90% with the remainder consisting of Fe-oxides, quartz, and clay minerals. The rock is porous and exceptionally permeable which 1) enables groundwater to easily percolate through the rock and 2) precipitate mineral deposits that cement the sediment together. In the colonial era, this rock was quarried for local building foundations. It’s not a particularly durable rock, but it was handy.

    5
    Katharine Celata and Monica Stone with compass plate and Brunton measuring the orientation of inclined strata at Cornwallis Cave (2012).

    Sedimentary layers that underlie the Coastal Plain are typically flat-lying or horizontal, and faithfully reflect the orientation in which the strata were originally deposited. But at Cornwallis Cave, our attention is piqued as the coquina layers are moderately inclined. One of our main tasks at the outcrop involves measuring the three-dimensional orientation of the layers using the Brunton compass. The outcrop surface is a cliff and generally not parallel to the layers, so we use our field clipboards as compass plates, holding them parallel to layering and measuring the strike and dip of the field clipboard as a proxy.

    Measuring rocks structures with a Brunton compass takes practice, and the 2019 class is still cutting its teeth. Improvement will follow.

    After making observations and measuring geological structures, we come up with a set of hypotheses to explain the orientation of layering. As I noted above, all across the Coastal Plain the strata are nearly horizontal – why are the strata at Cornwallis Cave inclined?

    One hypothesis is that the layers of broken shells accumulated in a horizontal position and were later tilted by tectonic activity. A competing hypothesis posits that the strata were deposited on an incline and never tilted. In certain depositional settings, such as on large dunes or submarine shoals, layers may be deposited at angles upwards of 30˚. At the base of the dune or shoal, these cross-beds become less steeply inclined and pass into a nearly horizontal orientation.

    How, in the field, do we evaluate these two hypotheses?

    We look at the outcrop once more. A close examination of the outcrop reveals fossil burrows (Ophiomorpha) in a nearly vertical orientation. These burrows disrupt the inclined layering, and their vertical attitude indicates that the strata were deposited on a slope. If the layers had been tilted after deposition, we’d expect the Ophiomorpha burrows to not be vertical.

    The inclined strata at Cornwallis Cave are part of a cross-bedded carbonate sequence that was deposited on the northwest edge of a submarine shoal or bar. Here in the shallow water, great quantities of shelly sediment were thrashed about and broken by waves with the sandy bits and pieces flushed over the shoal and down the steep leeward slope into deeper water.

    6
    Cross sectional interpretation of depositional environments associated with a submarine shoal during the deposition of the Yorktown Formation (modified from Johnson and others, 1998).

    The strata exposed at Cornwallis Cave are part of the Yorktown Formation, a widespread Pliocene marine deposit that underlies most of the Virginia Coastal Plain. The Yorktown Formation was deposited between 4 and 5 million years, when the ancient Atlantic Ocean’s waters reached as far west as Richmond (well, the area that would eventually become Richmond). These were subtropical seas with a plethora of organisms flourishing in its warm shallow waters.

    7
    Paleogeography of eastern Virginia during the Pliocene.

    I now have a 12-year time series from our yearly trips to Cornwallis Cave. The photos illustrate that the outcrop is suffering from a number of ailments, the most obvious are the festoons of English Ivy (Hedera helix) that seemingly cascade down the cliff face. In this setting, English Ivy is an invasive species and it’s hastening the weathering and disintegration of the outcrop.

    8
    Top – A 2014 image of Cornwallis Cave. Note the invasive English Ivy (Hedera helix) cascading down the cliff face. Bottom Left – English Ivy consumes Ben Weinmann in 2015. Bottom Right – The interior of Cornwallis Cave in 2019, note the Bud Ice beer can for scale and the inclined strata.

    Perhaps, General Cornwallis is exacting his revenge – English Ivy is destroying an important natural and historic American landmark at the very site where the United States won its independence. How cheeky!

    Something should be done to remediate this abomination. A first order fix would be to turn some patriotic goats loose on the English Ivy and other encroaching vegetation. After the goat platoon finishes its job, it’d be reasonable to gently power wash the cliff to remove the clingy bits of ivy rootlets and the myriad of microbial mats that currently coat the outcrop.

    The National Park Service maintains the Yorktown Battlefield as part of the Colonial National Historical Park, and is rightly concerned about deteriorating conditions on the inside of Cornwallis Cave (which is not accessible to the public). They should also be concerned about the exterior. Were this a historic building entrusted to the Park Service every effort would be made to preserve the structure for future generations, yet Cornwallis Cave suffers from benign neglect.

    The exposures at Cornwallis Cave are an important and accessible piece of America’s geological heritage, one that’s also intertwined with the final chapter of the American Revolution and our awful Civil War. That is certainly worth preserving.

    A few years hence, it’d be awesome to showcase photos of a crisp and clean Cornwallis Cave in all its geological splendor. We’d be keen to work with the Park Service on the preservation effort.

    The last stop on our geological siege of Yorktown takes us to the 2nd French Siege Line where we delve into a bit of interdisciplinary learning. Just as we’ve done since the first Earth Structure & Dynamics field trip to Yorktown in 2007, long before the COLL curriculum or interdisciplinarity became cool at W&M, students put themselves into character as a young staff officer serving the French field commander the Marquis de Lafayette.

    9
    A wet day on the 2nd French Siege Line (2018).

    10
    Marquis de Lafayette orders to his staff officers. Note the novel use of an American five dollar bill to measure the map scale!

    Lafayette asks the officer for the range and bearing to British Redoubt #9, so as to better train the battery of French cannons on the enemy’s position. Once again we employ our compass and some geometric know-how to provide the solution for Lafayette. The fall of British Redoubts #9 and #10 to French and American infantry on October 14th 1781 was the master stroke of the battle, as the Allied forces could then shell Yorktown at will. Soon after the redoubts were captured, Cornwallis asked for surrender terms.

    Our yearly siege of Yorktown is all about doing geology outside the classroom, but with a historic twist. For me it’s a late winter adventure that I look forward to because it builds community and we put into practice what we’ve worked to learn in the lab.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The College of William & Mary (also known as William & Mary, W&M, and officially The College of William and Mary in Virginia) is a public research university in Williamsburg, Virginia. Founded in 1693 by letters patent issued by King William III and Queen Mary II, it is the second-oldest institution of higher education in the United States, after Harvard University.

    William & Mary educated American Presidents Thomas Jefferson (third), James Monroe (fifth), and John Tyler (tenth) as well as other key figures important to the development of the nation, including the fourth U.S. Supreme Court Chief Justice John Marshall of Virginia, Speaker of the House of Representatives Henry Clay of Kentucky, sixteen members of the Continental Congress, and four signers of the Declaration of Independence, earning it the nickname “the Alma Mater of the Nation.” A young George Washington (1732–1799) also received his surveyor’s license through the college. W&M students founded the Phi Beta Kappa academic honor society in 1776, and W&M was the first school of higher education in the United States to install an honor code of conduct for students. The establishment of graduate programs in law and medicine in 1779 makes it one of the earliest higher level universities in the United States.

    In addition to its undergraduate program, W&M is home to several graduate programs (including computer science, public policy, physics, and colonial history) and four professional schools (law, business, education, and marine science). In his 1985 book Public Ivies: A Guide to America’s Best Public Undergraduate Colleges and Universities, Richard Moll categorized William & Mary as one of eight “Public Ivies”.

     
  • richardmitnick 4:00 pm on February 27, 2019 Permalink | Reply
    Tags: , , Geology, , Stanford’s School of Earth and Energy & Environmental Sciences (Stanford Earth), ,   

    From Stanford University: “Volcanoes, archaeology and the secrets of Roman concrete” 

    Stanford University Name
    From Stanford University

    February 26, 2019
    Josie Garthwaite

    Geophysical processes have shaped Pozzuoli, Italy, like few other places in the world. Stanford students applied modern tools to understand those links and what it means to live with natural hazards as both threat and inspiration.

    1
    Students gather atop Mount Vesuvius in southern Italy and listen as geophysicist Tiziana Vanorio discusses how volcanic activity has shaped the surrounding region. (Image credit: Kurt Hickman)

    High above Italy’s Tyrrhenian Sea, off the north coast of Sicily, 13 students sit atop Stromboli Volcano as it erupts. Ash falls on their shoulders and ping-ping-pings their helmets. The ground beneath their feet trembles.

    3
    The Island of Stromboli, Shot 2004 Sep 28 by Steven W. Dengler.

    “It’s one thing to read and talk about seismic and volcanic hazard; it’s another thing to experience it,” said geophysicist Tiziana Vanorio, an assistant professor in Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “I wanted to share this with them.”

    The journey to Stromboli had begun the day before in Vanorio’s hometown, Pozzuoli, a colorful port city founded by the Greeks and later occupied by the Romans, at the center of a volcanic caldera, or depression, known as Campi Flegrei. Vanorio, the 13 students and two teaching associates boarded a hydrofoil in Naples and sailed south across the deep blue water of the Tyrrhenian for nearly four quiet hours before catching sight of smoke, steam and gases puffing from Stromboli’s cone.

    2
    During their two-week trip, students visited two volcanoes in Italy and local towns shaped by their proximity. (Image credit: Yvonne Tang)

    Reaching the top would prove more arduous – a five-hour climb up steep slopes of ash and rock. Sedimentologist Nora Nieminski, a postdoctoral researcher at Stanford Earth and a guest instructor on the trip, sprinted ahead to shoot drone footage that she would later help the students manipulate to create 3D models of the volcano. But the rest of the group walked without hurry. Halfway to the top, they stopped to rest near a dark scar on the volcano’s northern flank known as the Sciara del Fuoco, where the volcano has collapsed on itself.

    Dionne Thomas, ’20, a student on the trip who is majoring in chemical engineering, remembers smelling dirt and ash, seeing the Tyrrhenian Sea reflecting the sky’s late-afternoon wash of orange and blue, and counting down the minutes between small bursts of lava from a caldera upslope. While she noticed the weight of exhaustion from the long climb, she said, “I felt really strong.”

    Thomas and the 12 other students on the trip visited Stromboli as part of a three-week seminar in southern Italy focused on volcanoes, archaeology and the science of Roman concrete – an exceptionally durable material that may hold insights for future materials that are more sustainable or even suitable for building habitats on Mars.

    Offered through Stanford’s Bing Overseas Studies Program, the seminar is an opportunity to draw visceral connections between science and history, and to gain a better understanding of Earth along the way.

    Nature’s laboratory

    The Neapolitan Province in southern Italy is an ideal place to dive into the science of natural hazards and how they have played into daily life and innovation over thousands of years. Densely populated and peppered with dozens of volcanoes, the region ranks as one of the most hazardous on Earth. The ruins of a Roman harbor and an emperor’s villa can be found offshore, sunken like Atlantis as a result of unrest in Earth’s crust. “Not many places on Earth experience this kind of seismicity and volcanism, while being an ancient town and functioning as a modern society,” Vanorio said. “That’s the beauty of the place.”

    Underlying the seminar’s excursions and daily lessons in geophysics, the properties of Roman concrete and 3D modeling from drone images was a larger exercise in finding connections between different fields of study. It’s no accident that students chosen to participate in the seminar represented a wide range of majors, including computer science, physics, classics, chemical engineering and political science.

    3
    The ancient Italian city of Pozzuoli was shaped by volcanic activity. (Image credit: Kurt Hickman)

    “There are still scientific questions that we don’t know how to answer,” said Vanorio, who discovered natural processes deep in the subsurface of Campi Flegrei that mirror those in Roman concrete, and has used historical texts to shed light on strengths and the characteristics of both volcanic and engineered materials. “The more we leverage knowledge across different disciplines, the more we can address and solve those problems.”

    For Amara McCune, BS ’18, who joined a previous seminar in the region led by Vanorio in 2016, the intermingling of geophysics with dives into the region’s culture proved a powerful mix. “The unique combination of learning about Pompeii, volcanic uplift and Rome while being on-site, hearing from local guides and having archaeological and geological experts point out features of a location made for an incredibly rich learning experience,” she said.

    ______________________________________________________________________
    Materials inspired by nature
    4
    Romans used concrete made with volcanic ash to build long-lasting structures like the amphitheater in Pozzuoli, Italy. (Image credit: Nora Nieminski)

    Nearly all concrete today is based on a recipe developed in the early 1800s, which requires a process that’s heavily carbon-intensive. But ancient Romans invented a different recipe for concrete structures that have survived for millennia. Research now suggests this ancient material and the volcanoes that made its key components may hold clues for more sustainable building materials.
    ______________________________________________________________________

    Now pursuing a PhD in physics, McCune said the seminar in southern Italy helped to broaden her thinking about how she might apply her degree. “It made me more open to different fields and eager to learn the history and intricacies of the natural world around us,” she said.

    During the most recent trip, darkness fell as the group, giddy in anticipation of the volcano’s powerful eruptions, settled in around Stromboli’s rim. “It explodes violently and without warning – these big, loud bang explosions followed by incandescent ash flying into the air,” explained Dulcie Head, a teaching assistant on the trip and a PhD student in geophysics.

    By this time, the students could see the ash swirling around them as more than volcanic dirt. They knew that similar ash had been a key ingredient in construction of the amphitheater, harbor and ancient marketplace in Pozzuoli, and even the Pantheon in Rome, with its massive, unreinforced dome – the largest in the ancient world.

    “Pozzuoli is possibly the place where Romans, by looking at nature, were inspired to make an iconic material,” Vanorio said. They developed a recipe for concrete that lasts for thousands of years using volcanic ash, lime, tiny volcanic rocks and water, while modern concrete often crumbles within 50 years.

    Atop Stromboli, which scientists carefully monitor for safety, the students also had enough Earth science churning through their heads to see the volcano itself as a natural laboratory. “This volcano is literally producing new rocks as we’re sitting here. It’s throwing them at us,” Head explained. “It’s exciting to see such an active process, where a natural event also produces new materials.”

    The group bounced and slid down a path on the volcano’s slopes wearing gas masks to protect their lungs from ash and sand kicked up by their feet. Back at their hotel at the foot of the island, they peeled off their masks and washed away Stromboli’s detritus. Later, the group learned how to calculate the trajectory and velocity of the volcano’s arcing ash projectiles with particle-tracking software.

    “This was one way for us to use time-lapse images,” Vanorio said. “I wanted students from Earth science, from the classics, and engineers to learn how to use this tool because we are finding ourselves using these kinds of images more and more – often captured by drone – whether it’s to analyze inaccessible outcrops of rocks or map vast ancient sites or a building.”

    What could have seemed like abstract calculations took on greater resonance in light of the group’s up-close encounter with the eruption. “I’ll never forget the bright sparks of the eruption against the dark night,” said Sylvia Choo, ’20, who is majoring in classics and biology. “It was incredible to experience the great force of nature.”

    Ancient city

    Some 150 miles across the cool Tyrrhenian, within the Campi Flegrei or “Burning Fields” caldera, lies downtown Pozzuoli. In this city best known to many Italians as the birthplace of Sophia Loren, the ruins of a Roman marketplace are a hub for cross-disciplinary connections.

    Pozzuoli sits on a restless, Manhattan-sized swath of coast where the rotten-egg smell of sulfur laces the air. Solfatara crater, home of Vulcan, the Roman god of fire, gurgles on the edge of town. And just offshore, sculptures, thermal baths, a villa, bright tiled mosaics and other archaeological ruins rest more than 30 feet below sea level, victims of the caldera’s subsidence.

    5
    Parts of Pozzuoli’s ancient architecture contain records of long-term subsidence and brief periods of uplift. Rapid uplift during the 1980s left the town’s harbor too shallow for docking. (Image credit: Kurt Hickman)

    6
    Students swam through a sunken Roman resort town in the underwater archaeological park of Baiae off the coast of Pozzuoli. (Image credit: Kurt Hickman)

    Near Pozzuoli’s modern-day waterfront, three columns stand amid the ruins of the old marketplace, or Macellum. The students knew from their studies on campus in the spring that the marble trio held a 2000-year record of long-term subsidence and brief periods of uplift. So as the columns came into view when the group first walked down from their villa residence, several students exclaimed, “Oh, there they are!”

    Gathering close to the columns for a lecture from Vanorio while Nieminski’s drone buzzed overhead, they could see bands of tiny holes bored by so-called “stone-eater” mussels – marine mollusks that drilled up and down the columns as the rise and fall of the caldera changed how much of the structures extended above the waterline. “They literally made a mark on history,” Choo said.

    Using skills developed in on-campus seminars led by Nieminski, the students were able to analyze history at the Macellum and other sites with a lighter touch. They built 3D models of the marketplace from Nieminski’s drone imagery and manipulated them with software to take measurements and answer scientific questions of their own devising.

    Thomas, for example, examined the different materials in the columns to understand how weathering and water pressure from below played out over time. The project, she said, allowed her to weave together knowledge from chemical engineering, physics and math, as well as the geophysics lessons from the seminar. “After this seminar, I am even more convinced that many fields can overlap,” she said.

    Restless Earth

    Ups and downs are part of the fabric of life in Pozzuoli. In the early 1980s, the ground rose more than 6 feet in just two years, an alarming rate of uplift that reshaped the town, leaving the harbor too shallow for docking and forcing the relocation of schools and shops.

    The rising seabed also triggered enough earthquakes to prompt evacuation of nearly 40,000 people – including Vanorio, then a teenager – for two years beginning in 1982. “Everyone was worried,” she said. “People were expecting an eruption, and we were really concerned about the seismic hazard. The houses were not retrofitted seismically.”

    But as seminar students learned through lectures and readings this summer, the episode tipped off Stanford scientists to an unusual toughness in the rock here. Other volcanic calderas, like Yellowstone or the Long Valley, located east of Yosemite National Park, tend to release the energy accumulated from uplift fairly soon through earthquakes. “Those calderas experience uplift and then almost immediately, seismic activity starts,” Vanorio explained. “The rocks deform and then they fracture.”

    In Pozzuoli, earthquakes didn’t begin until the Campi Flegrei caldera had deformed by nearly 3 feet. “The question from a rock physics point of view has been, what kind of rocks in the subsurface are able to accommodate such large strain without immediately cracking?” The rock capping this caldera, it turns out, contains fibrous minerals mirroring those in Roman concrete that allow it to stretch and bend before failing under stress.

    At the marketplace, Vanorio also pointed out that the durability of Roman concrete can be seen in sections of the ancient walls where the bricks made of tuff – a kind of volcanic rock – eroded away long ago, but the mortar made with volcanic ash and lime still remains. “At the end of the day, these ancient sites are made of Earth materials that degrade and change over time,” Vanorio said. “We can use rock physics to understand those materials and learn to preserve them better.”

    See the full article here .


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    Please help promote STEM in your local schools.

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    Stanford University campus. No image credit

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 3:23 pm on February 27, 2019 Permalink | Reply
    Tags: A one-stop link allowing earth scientists to access all the data they need to tackle big questions such as patterns of biodiversity over geologic time and the distribution of metal deposits also the w, , British Geological Survey, Geology, , , This network of earth science databases called Deep-time Digital Earth (DDE)   

    From Science Magazine: “Earth scientists plan to meld massive databases into a ‘geological Google’’ 

    AAAS
    From Science Magazine

    Feb. 26, 2019
    Dennis Normile

    1
    Deep-time Digital Earth aims to liberate data from collections such as the British Geological Survey’s. British Geological Survey.

    The British Geological Survey (BGS) has amassed one of the world’s premier collections of geologic samples. Housed in three enormous warehouses in Nottingham, U.K., it contains about 3 million fossils gathered over more than 150 years at thousands of sites across the country. But this data trove “was not really very useful to anybody,” says Michael Stephenson, a BGS paleontologist. Notes about the samples and their associated rocks “were sitting in boxes on bits of paper.” Now, that could change, thanks to a nascent international effort to meld earth science databases into what Stephenson and other backers are describing as a “geological Google.”

    This network of earth science databases, called Deep-time Digital Earth (DDE), would be a one-stop link allowing earth scientists to access all the data they need to tackle big questions, such as patterns of biodiversity over geologic time, the distribution of metal deposits, and the workings of Africa’s complex groundwater networks. It’s not the first such effort, but it has a key advantage, says Isabel Montañez, a geochemist at University of California, Davis, who is not involved in the project: funding and infrastructure support from the Chinese government. That backing “will be critical to [DDE’s] success given the scope of the proposed work,” she says.

    In December 2018, DDE won the backing of the executive committee of the International Union of Geological Sciences, which said ready access to the collected geodata could offer “insights into the distribution and value of earth’s resources and materials, as well as hazards—while also providing a glimpse of the Earth’s geological future.” At a meeting this week in Beijing, 80 scientists from 40 geoscience organizations including BGS and the Russian Geological Research Institute are discussing how to get DDE up and running by the time of the International Geological Congress in New Delhi in March 2020.

    DDE grew out of a Chinese data digitization scheme called the Geobiodiversity Database (GBDB), initiated in 2006 by Chinese paleontologist Fan Junxuan of Nanjing University. China had long-running efforts in earth sciences, but the data were scattered among numerous collections and institutions. Fan, who was then at the Chinese Academy of Sciences’s Nanjing Institute of Geology and Paleontology, organized GBDB around the stacks of geologic strata called sections and the rocks and fossils in each stratum.

    Norman MacLeod, a paleobiologist at the Natural History Museum in London who is advising DDE, says GBDB has succeeded where similar efforts have stumbled. In the past, he says, volunteer earth scientists tried to do nearly everything themselves, including informatics and data management. GBDB instead pays nonspecialists to input reams of data gleaned from earth science journals covering Chinese findings. Then, paleontologists and stratigraphers review the data for accuracy and consistency, and information technology specialists curate the database and create software to search and analyze the data. Consistent funding also contributed to GBDB’s success, MacLeod says. Although it started small, Fan says GBDB now runs on “several million” yuan per year.

    Earth scientists outside China began to use GBDB, and it became the official database of the International Commission on Stratigraphy in 2012. BGS decided to partner with GBDB to lift its data “from the page and into cyberspace,” as Stephenson puts it. He and other European and Chinese scientists then began to wonder whether the informatics tools developed for GBDB could help create a broader union of databases. “Our idea is to take these big databases and make them use the same standards and references so a researcher could quickly link them to do big science that hasn’t been done before,” he says.

    The Beijing meeting aims to finalize an organizational structure for DDE. Chinese funding agencies are putting up $75 million over 10 years to get the effort off the ground, Fan says. That level of support sets DDE apart from other cyberinfrastructure efforts “that are smaller in scope and less well funded,” Montañez says. Fan hopes DDE will also attract international support. He envisions nationally supported DDE Centers of Excellence that would develop databases and analytical tools for particular interests. Suzhou, China, has already agreed to host the first of them, which will also house the DDE secretariat.

    DDE backers say they want to cooperate with other geodatabase programs, such as BGS’s OneGeology project, which seeks to make geologic maps of the world available online. But Mohan Ramamurthy, project director of the U.S. National Science Foundation–funded EarthCube project, sees little scope for collaboration with his effort, which focuses on current issues such as climate change and biosphere-geosphere interactions. “The two programs have very different objectives with little overlap,” he says.

    Fan also hopes individual institutions will contribute, by sharing data, developing analytical tools, and encouraging their scientists to participate. Once earth scientists are freed of the drudgery of combing scattered collections, he says, they will have time for more important challenges, such as answering “questions about the evolution of life, materials, geography, and climate in deep time.”

    See the full article here .


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  • richardmitnick 9:58 am on February 26, 2019 Permalink | Reply
    Tags: "Seismic warning to India: A shock strikes just north of Delhi", , , , , Geology, , ,   

    From temblor: “Seismic warning to India: A shock strikes just north of Delhi” 

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    From temblor

    February 25, 2019
    By Aron Mirwald, M.Sc.
    Ross Stein, Ph.D., Temblor, Inc.

    On 20 February 2019, a magnitude 4 earthquake struck 50 km (30 mi) north from the megacity, Delhi. A magnitude 4 earthquake is not large. If it occurs nearby, it can be felt, and may generate some damage, but it is almost never fatal. This earthquake was no exception: shaking has been reported to be weak to moderate. So, what is interesting about it? Actually, there is a lot to be learned from small, seemingly unimportant events like this. Let us use this earthquake as a means to explore the seismic risk in India.

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    This portion of a new map from the GEM Foundation shows the expected cost of earthquake damage relative to the cost of construction, averaged over time, everywhere on Earth. The Himalayan Foothill Thrust region lights up in a band of yellow-orange high risk. The risk is the product of a very high seismic hazard and an extremely high population density. Pakistan and Nepal are also seen to be at very high risk, followed by greater Kabul in Afghanistan.

    Crushing into Eurasia

    We know from GPS observations that the Indian plate is moving 16-18 millimeters per year towards the Eurasian plate (Bilham & Ambraseys, 2005). It is pushed, rather forcefully, below the Eurasian plate. This movement has resulted in the creation of the beautiful Himalayas. But it has also resulted in a thrust-zone, where many great earthquakes occur. In this zone, the two plates are interlocked most of the time. Since the plate is pushing from behind, the stress builds up until it is strong enough to overcome fault friction. Then, very large earthquakes can occur.

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    India has been in a slow-motion crash into Asia for 40 million years, as attested to by 500 years of historical reports of great earthquakes, with events striking principally along India’s northern frontier. Some 400 million people live in the Ganges Plain (bright white area), just south of the frontier, in India and Bangladesh. Graphic by Volkan Sevilgen.

    At the thrust-zone between the Indian and Eurasian plate, at least three earthquakes with a magnitude larger than 8 have occurred in medieval times (Bilham, 2009). The recurrence time of this kind of earthquakes is unknown, but it is speculated that earthquakes of similar magnitude are overdue (Bilham & Ambraseys, 2005).

    But, if we take a closer look at last week’s earthquake, it did not occur at the thrust-zone, but further in the south. Actually, there are many earthquakes known to occur far away from the thrust-zone. This could be easily explained, if the Indian plate itself was deformed substantially. But, we know that the rate of deformation along the continent is very low, around 5 millimeters per year (Bilham, 2004). This is too low to explain frequent seismicity.

    The Indian plate is buckling

    The explanation is simple, yet fascinating. The downward bend of the Indian plate beneath the Himalayas has resulted in a ‘flexure’, or bending, of the plate. We can see this in the cross—section south of the thrust-zone. There is first an upward bulge of approximately 450 meters, followed by a smaller depression (Bilham, 2004). Now, we can imagine the plate to be like a wooden stick: it bends before it breaks.

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    In this cross-section, North is to the right, and South to the left. The buckling of the Indian plate leads to a bulge south of Delhi, along with shallow tensional quakes, as struck last week. The great earthquakes strike along the thrust fault at right (purple), as well as other sites of concentrated buckling (Bilham, 2009).

    The first part that breaks is usually a weak spot. In tectonic plates such weak spots are often faults, planes where the rock has failed previously due to an earthquake. Weak planes, that were previously stable, will be pushed towards the thrust-zone, and move through the bulge, where the change of flexural stresses can trigger failure and consequently earthquakes.

    Seismic Risk in India

    Now we can put the picture together: Seismic risk in India can be attributed to earthquakes at the thrust-zone below the Himalayas, and to seismicity within the continent due to flexural stresses.

    Delhi, as an example of a vulnerable metropolis, has a history of being affected by both (Iyengar, 2000). There are around 20 seismically active faults in the vicinity of Delhi capable of generating earthquakes. The Mahendraghar–Dehradhun fault, for instance, could produce an earthquake of magnitude 7 (Iyengar & Gosh, 2004). One problem is, that the fast urbanization in Delhi is leading to a rising number of buildings that are helpless even in the face of moderate sized earthquakes (Mittal et. al., 2012).

    India is one of the countries with the most earthquake-related deaths. Just in the past century, over 100.000 people have died due to earthquakes in the country (Bilham, 2009). This number is unlikely to decrease in the future: Its population is growing, and the consequential increase of fatalities is foreseeable (Bilham, 2009).

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    India lies in the cluster of countries in the upper right, which have suffered the largest number of large earthquakes and fatalities since the turn of the 19thth century (Bilham, 2009)

    Hope for the best, prepare for the worst

    In their hazard assessment, Nath and Thingbaijam (2012) conclude that the Bureau of Indian Standards underestimates the seismic risk in India and recommend updating the National Building Code. But there is another problem. According to Bilham (2009), constructers often ignore existing building codes. Among the reasons he lists are ignorance of the seismic risk and the engineering solutions to it, people trying to save money, and corruption. He suggests that this could be solved by education. If everybody knew about the fatal consequences of not including earthquake resistant structures, it would occur less frequently.

    Often, action is only taken after the disaster, but that is too late for many. So, this comparatively small earthquake near the megacity should be a reminder to put more effort to raise awareness of the earthquake risk.

    References

    Bilham, Roger. The seismic future of cities. Bulletin of Earthquake Engineering, 2009, 7. Jg., Nr. 4, S. 839.
    Bilham, Roger, et al. Earthquakes in India and the Himalaya: tectonics, geodesy and history. Annals of GEOPHYSICS, 2004.
    Bilham, Roger; AMBRASEYS, Nicholas. Apparent Himalayan slip deficit from the summation of seismic moments for Himalayan earthquakes, 1500–2000. Current science, 2005, S. 1658-1663.
    GEM Global Seismic Risk Map (Silva et al., 2018), https://maps.openquake.org/map/global-seismic-risk-map/
    Iyengar, R. N. Seismic status of Delhi megacity. Current Science, 2000, 78. Jg., Nr. 5, S. 568-574.
    Iyengar, R. N.; GHOSH, Susanta. Microzonation of earthquake hazard in greater Delhi area. Current Science, 2004, 87. Jg., Nr. 9, S. 1193-1202.
    Mittal, Himanshu, et al. Stochastic finite modeling of ground motion for March 5, 2012, Mw 4.6 earthquake and scenario greater magnitude earthquake in the proximity of Delhi. Natural Hazards, 2016, 82. Jg., Nr. 2, S. 1123-1146.
    Nath, S. K.; Thingbaijam, K. K. S. Probabilistic seismic hazard assessment of India. Seismological Research Letters, 2012, 83. Jg., Nr. 1, S. 135-149.

    See the full article here .


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

    Please help promote STEM in your local schools.

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    Earthquake Alert

    1

    Earthquake Alert

    Earthquake Network project

    Earthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

    The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

    Get the app in the Google Play store.

    3
    Smartphone network spatial distribution (green and red dots) on December 4, 2015

    Meet The Quake-Catcher Network

    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).

    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

    ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States
    1

    The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

    Watch a video describing how ShakeAlert works in English or Spanish.

    The primary project partners include:

    United States Geological Survey
    California Governor’s Office of Emergency Services (CalOES)
    California Geological Survey
    California Institute of Technology
    University of California Berkeley
    University of Washington
    University of Oregon
    Gordon and Betty Moore Foundation

    The Earthquake Threat

    Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

    Part of the Solution

    Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

    Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

    System Goal

    The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

    Current Status

    The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

    In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

    This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

    Authorities

    The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

    For More Information

    Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
    rdegroot@usgs.gov
    626-583-7225

    Learn more about EEW Research

    ShakeAlert Fact Sheet

    ShakeAlert Implementation Plan

     
  • richardmitnick 1:25 pm on January 23, 2019 Permalink | Reply
    Tags: , Ancient Faults Amplify Intraplate Earthquakes, , , Geology, , Seismicity   

    From Eos: “Ancient Faults Amplify Intraplate Earthquakes” 

    From AGU
    Eos news bloc

    From Eos

    1.23.19
    Terri Cook

    A comparison of deformation rates from Canada’s Saint Lawrence Valley offers compelling evidence that strain in the region is concentrated along ancient structures from previous tectonic cycles.

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    A scientist sets up GPS equipment in Murray, Quebec. GPS measurements from Canada’s Saint Lawrence Valley may shed new light on the causes of poorly understood earthquakes that occur far from tectonic plate boundaries. Credit: Stephane Mazzotti

    Although earthquakes that strike in the interior of tectonic plates can inflict widespread damage, the processes that drive this type of seismicity are still poorly understood. This is partly due to the lower rates of deformation occurring in these regions compared to those at plate boundaries. Researchers have proposed that intraplate deformation is concentrated along ancient faults inherited from earlier cycles of tectonic activity. But exactly how these inherited structures influence modern seismicity remains a topic of vigorous debate.

    2
    Researchers installed GPS equipment in Havre-Saint-Pierre, Quebec, to help unravel the mechanics behind intraplate earthquakes. Credit: Stephane Mazzotti

    Now Tarayoun et al. [JGR Solid Earth] have quantified the impact of inherited structural features on the deformation occurring within eastern Canada’s Saint Lawrence Valley, a region that has experienced two full cycles of ocean basin inception and closure during the past 1.3 billion years. Using new episodic and continuous GPS data acquired from 143 stations, the team calculated surface deformation rates across the region and compared them to the rates predicted by models of glacial isostatic adjustment (GIA), the main process controlling deformation in the valley today.

    The results indicate that within the Saint Lawrence Platform—the geological province paralleling the Saint Lawrence River that is riddled with inherited, large-scale faults—the rates of deformation average 2 to 11 times higher than those measured in the surrounding provinces. And although the GPS-derived and GIA-predicted deformation rates generally agree in the surrounding provinces, the GPS-calculated rates are, on average, 14 times higher than those predicted by GIA models within the Saint Lawrence province. This result strongly suggests this zone of inherited structures concentrates modern surface deformation.

    This research offers compelling evidence that the Saint Lawrence Valley represents a zone of high intraplate deformation, controlled by forces linked to the region’s postglacial rebound and amplified by inherited structures from earlier tectonism. As the first study to quantify the impact of structural inheritance on surface deformation, this groundbreaking research will help unravel the processes that control deformation, as well as the poorly understood earthquakes that occur in the center of tectonic plates.

    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.

     
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