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  • richardmitnick 10:43 am on July 7, 2019 Permalink | Reply
    Tags: "Oregon Is About to Get a Lot More Hazardous", , , Landslides and debris flows, , Tsunamis,   

    From Scientific American: “Oregon Is About to Get a Lot More Hazardous” 

    Scientific American

    From Scientific American

    June 29, 2019
    Dana Hunter

    State leadership is failing its citizens—and there will be a body count.

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    Credit: Dale Simonson (CC BY-SA 2.0)

    When you live in an area at as much geologic risk as Oregon, you would expect that government officials would maybe, possibly, take those risks seriously. But the people who currently govern Oregon seem quite determined to ignore hazards and let the state languish unprepared.

    It’s bad enough that legislators voted this month to allow “new schools, hospitals, jails, and police and fire stations” to be built in areas that will most certainly be inundated in the event of a tsunami. Both parties think it’s a good idea now; I doubt they’ll still be feeling great about locating schools right in the path of rampaging seawater when the big one hits. But short-term economic gain outweighs long-term planning, so here we are. What else can we expect from a statehouse where lawmakers who would rather flee the state than be forced to deal with climate change?

    People say they’re willing to accept the risks. However, the state government is now planning to make it far harder for residents to even know what those risks are, because Oregon’s Department of Geology and Mineral Industries (DOGAMI for short) is severely underfunded and will now lose three critically-needed experts on staff as a punishment for going over budget. As if that weren’t bad enough, the governor’s office is considering whether the agency should even continue to exist:

    “In a note on the preliminary budget proposal for the agency, the Joint Ways and Means Committee said the Governor’s office would be “evaluating if the Department should continue to exist as an independent or recommendations to abolish and move the individual programs to other entities.”

    That drastic of a move could come with big consequences,” Avy said.

    “It would be incredibly disruptive to staff and it is likely that some on-going studies would be discontinued,” he said.”Oregon would lose a valued agency and may lose talented staff in our Geological Survey and Services Program which provides a focus on geologic and mineral mapping and natural hazard identification.”

    Can we be real for a minute, here? Oregon is a geologically young state in an active subduction zone, located on an ocean that has subduction zones on both sides, which generate ocean-spanning tsunamis on a regular basis. The local subduction zone, plus Basin and Range crustal stretching and faulting, also produces active volcanoes. Many, many volcanoes. Also, too, all of this folding and faulting and uplifting and volcanoing leaves the state terribly landslide prone. This is not a place where you can safely starve your local geological survey of funds, and then shut it down when it needs extra money to identify and quantify the hazards you face.

    So if you live in Oregon, or even if you just visit, I’d strongly consider writing a polite but serious missive to Governor Kate Brown, letting her know that it would perhaps be a good idea to look further into the possible repercussions of signing that deplorable tsunami bill (I mean, at least take the schools out of the mix!), and also fully fund DOGAMI rather than further crippling it and then stripping it for parts.

    Let’s have a brief tour of Oregon’s geohazards which DOGAMI helps protect us from, then, shall we?

    Tsunamis

    The Oregon coast is extremely susceptible to tsunamis, both generated from Cascadia and from other subduction zones along the Pacific Ocean. You can see evidence of them everywhere.

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    Cascadia subduction zone. This is the site of recurring en:megathrust earthquakes at average intervals of about 500 years, including the en:Cascadia Earthquake of en:1700.

    One of the starkest reminders in recent times was the dock that was ripped from the shoreline in Misawa, Japan, in the brutal 2011 Tōhoku Earthquake. The tsunami that sheared it loose and set it afloat also washed ashore in California and Oregon, causing millions of dollars in damage; loss of life in the United States was only avoided due to ample warnings.

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    Ocean energy distribution forecast map for the 2011 Sendai earthquake from the U.S. NOAA. Note the location of Australia for scale.

    Just over a year later, the dock washed up on Agate Beach, Oregon.

    At Agate Beach, homes and businesses are built right in the path of the next Cascadia tsunami. I can’t describe to you the eerie sensation you feel turning away from that dock to see vulnerable structures that will be piles of flooded rubble after the next tsunami hits.

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    Residences and businesses on Agate Beach. Even a modest tsunami will cause untold damage to these structures. Credit: Dana Hunter

    The people here will have minutes to find high ground after the shaking stops, if that long. There is some high ground nearby, but not much, and perhaps not near enough. Roads will probably be destroyed or blocked in the quake. This is the sort of location the legislature has decided it would be fine to site schools.

    Earthquakes

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    The stump of a drowned spruce at Sunset Bay, Shore Acres, OR. Lockwood DeWitt for scale. Credit: Dana Hunter

    Sunset Bay is the site of one of Oregon’s many ghost forests. Here, a Cascadia earthquake dropped the shoreline about 1,200 years ago, suddenly drowning huge, healthy trees in salt water. At least seven spectacular earthquakes have hit the Oregon coast in the past 3,500 years. It may not sound like much, or often… but look to Japan for the reason why we should take the threat extremely seriously. And Oregon doesn’t just have to worry about Cascadia quakes: the state is full of faults, stretching from north to south and from coast to interior.

    Volcanoes

    Huge swathes of Oregon are volcanic. As in, recently volcanic. As in, will definitely erupt again quite soon.

    Mount Hood, a sibling to Mount St. Helens, is right outside of Portland and last erupted in the mid-1800s. It is hazardous as heck.

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    Mount Hood reflected in Trillium Lake, Oregon, United States

    But Hood is very, very far from the only young volcano in the state, and evidence of recent eruptions is everywhere. Belknap shield volcano and its associated volcanoes on McKenzie Pass ceased erupting only 1,500 years ago, and the forces that created it are still active today.

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    Belknap Crater, Oregon. Cascades Volcano Observatory

    Another volcanic center like it could emerge in the near future. And you see here just a tiny swath of the destruction such a volcanic center causes.

    You know what you really don’t want to be caught unawares by? A volcano. And even once they’ve stopped erupting, the buggers can be dangerous. Sector collapses, lahars, and other woes plague old volcanoes. You need people who can keep a sharp eye on them. And I’m sorry, but the USGS can’t be everywhere at once. Local volcano monitoring is important!

    Landslides and debris flows

    If you’re an Oregon resident, you’ll probably remember how bloody long it took to finish the Eddyville Bypass due to the massive landslide that got reactivated during construction. Steep terrain plus plenty of rain equals lots of rock and soil going where we’d prefer it didn’t.

    Debris flows and landslides regularly take out Oregon roads, including this stretch on a drainage by Mount Hood.

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    Construction equipment copes with damage caused by massive debris flows coming down from Mount Hood. Credit: Dana Hunter

    We know from the Oso mudslide just how deadly these mass movements can be. Having experts out there who understand how to map the geology of an area and identify problem areas is critically important, especially in places where a lot of people want to live, work, and play.

    Contact the governor’s office and let her know if you don’t think it’s worth letting a budget shortfall torpedo the agency that should be doing the most to identify these hazards and help us mitigate them.

    See the full article here .


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  • richardmitnick 2:33 pm on October 10, 2017 Permalink | Reply
    Tags: , , , Ritter Island, Tsunamis, Volcanic islands are the source of some of the world’s largest landslides,   

    From Eos: “An 1888 Volcanic Collapse Becomes a Benchmark for Tsunami Models” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    10.10.17
    Aaron Micallef
    Sebastian F. L. Watt
    Christian Berndt
    Morelia Urlaub
    Sascha Brune
    Ingo Klaucke
    Christoph Böttner
    Jens Karstens
    Judith Elger

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    Scientists aboard the R/V Sonne (shown here) profiled the seafloor and subsurface structures near Ritter Island, north of New Guinea, in 2016. A large portion of this volcanic island collapsed and slid into the sea in 1888, making it an ideal case study for modeling volcanic collapse landslides and the tsunamis they generate. Credit: Christian Berndt

    Early one March morning in 1888, a 4-cubic-kilometer chunk of the Ritter Island volcano collapsed into the Bismarck Sea northeast of New Guinea. This volume of land was about twice that of the Mount St. Helens landslide in 1980, and it is the largest historically recorded tsunami-causing volcanic sector collapse.

    The ensuing landslide triggered a tsunami tens of meters high. The waves were still 8 meters high when they reached parts of the island of New Guinea that are several hundreds of kilometers away, according to observers who witnessed the event [Ward and Day, 2003].

    Volcanic islands are the source of some of the world’s largest landslides. These landslides have the potential to generate large tsunamis. Scientists have debated the magnitude of these tsunamis, but much uncertainty remains over landslide dynamics and how far a tsunami can travel across an ocean basin while remaining large enough to cause damage.

    Studies of Ritter Island’s landslide and ensuing tsunami could significantly reduce that uncertainty. During a 6-week-long expedition in November and December 2016 aboard the German R/V Sonne, we mapped the Ritter Island collapse scar and deposit using hull-mounted multibeam sonar systems, which produced high-resolution bathymetry (Figure 1) and acoustic backscatter data.

    We are using data from this expedition, alongside a range of direct observations and samples, to generate a detailed interpretation of the Ritter Island landslide. With these robust field data, we set the stage for testing coupled landslide-tsunami models.

    An Ideal Study Site

    Ritter Island’s historic landslide, along with a heightened awareness of tsunami hazards following several recent devastating events, has caused some to wonder if other volcanic islands could experience flank or total collapse and, if so, how far tsunamis could reach. One hypothetical scenario that captured the attention of the popular media in 2004 involves a potential collapse of the Cumbre Vieja volcano on the southern half of the island of La Palma, one of the Canary Islands off the northwest coast of Africa.

    Such a collapse could trigger a tsunami that races across the Atlantic Ocean. However, recent tsunami models span an order of magnitude in their predictions of far-field wave heights for the La Palma collapse scenario.

    Resolving such discrepancies in our understanding of landslide and tsunami processes requires a field data set in which both phenomena can be observed to test current models. The sector collapse of Ritter Island, Papua New Guinea, in 1888 meets both these criteria.

    The landslide generated a tsunami that devastated shorelines as far as 600 kilometers away [Day et al., 2015]. An important factor is that there are eyewitness observations of the tsunami height, arrival time, and frequency at a range of locations around the Bismarck Sea [Day et al., 2015]. The event can thus be used as a benchmark for testing models of landslide-generated tsunamis if the volume, distribution, and dynamics of the landslide mass can be reconstructed.

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    Fig. 1. (a) Three-dimensional view of the Bismarck Sea between Umboi and Sakar islands compiled using data from the SO-252 multibeam echo sounder, bathymetric data from the General Bathymetric Chart of the Oceans (GEBCO), and altimetry from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite. The gray transparent cone represents Ritter Island before the 1888 event. Black lines and the red box indicate 2-D and 3-D seismic reflection data, respectively, acquired during the SO-252 expedition. The white arrows here and below indicate the direction of material mobilization during the 1888 event. (b) Three-dimensional reflection seismic data (from the area in the red box above) showing the Ritter Island deposit, remnant block, and parasitic volcanic cone. No image credit.

    Geological Setting

    Ritter Island is located north of Australia in the Bismarck Sea about 80 kilometers north of New Guinea and some 20 kilometers off the western end of New Britain. Situated between the islands of Umboi and Sakar (Figure 1), it forms part of the Bismarck Volcanic Arc, which results from the northward subduction of the Solomon Plate underneath the Bismarck Plate [Baldwin et al., 2012]. Today, Ritter Island is a narrow, crescent-shaped island, around 1.2 kilometers long and 200 meters wide, reaching an elevation of approximately 140 meters above sea level.

    This island is all that remains of a larger, steep-sided conical island that was around 750 meters high before it collapsed in 1888 [Day et al., 2015]. During the 19th century, Ritter Island was known among navigators in the region as a highly active volcano, characterized by frequent Strombolian activity [Johnson, 2013].

    There is evidence for several submarine eruptions since 1888 that have constructed a cone with a current summit around 200 m beneath sea level. The remnant of the island above the waterline is dominated by interbedded sequences of basaltic scoria and thin lava flows that are consistent with low-level Strombolian activity.

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    This arc is all that remains of the Ritter Island volcanic cone. Underwater deposits show clear evidence of the landslide triggered by the collapsing cone, and eyewitness accounts described the resulting tsunami. Credit: Christian Berndt.

    Contemporary observations of the tsunami triggered by the 1888 event suggest a single wave train, which is consistent with one main phase of landslide movement and tsunami generation [Day et al., 2015]. The landslide deposit is young enough to be preserved at the seafloor without significant overlying sedimentary cover, so it can be examined today to understand the emplacement dynamics of a large volcanic island landslide.

    Volcanic island landslides with volumes of 1 to 10 cubic kilometers, such as the Ritter Island landslide, have a global recurrence interval of 100 to 200 years [Day et al., 2015]. Therefore, a similar event is likely to occur in the next 100 years, in contrast to the extremely large ocean island collapses (e.g., Canary Islands and Lesser Antilles) that have recurrence intervals of tens of thousands of years or more.

    Collecting the Field Data Set

    During our 2016 expedition, we used a Parasound subbottom profiler with 10-centimeter resolution, as well as 2-D multichannel seismic data and P-Cable 3-D reflection seismic data acquisition systems to image the collapse deposit with 5-m vertical and horizontal resolution (Figure 1). Additional observations and samples collected across the deposit and island flanks, using towed video cameras and sediment samplers, provide ground truthing of the geophysical data and allow us to construct a detailed interpretation of landslide emplacement processes.

    The acquired data show the three-dimensional structure of the Ritter Island landslide deposit and enabled us to reconstruct the kinematics of the emplacement process. The new data set will be used to do the following:

    quantify the overall volume of the material that has been mobilized
    decipher the nature and extent of landslide disintegration
    determine the location, distribution, and size of transported blocks
    identify the nature and origin of different regions of the landslide deposit
    understand the relationship between landslides and the eruption history of Ritter Island and surrounding volcanoes

    These are key parameters for determining the landslide failure and emplacement process and the dynamics of the 1888 tsunami. An initial assessment of the data indicates that the flanks of Ritter Island below sea level expose clastic sequences similar to those in the scar above the water, with an increase in more massive lava units in the lowermost part of the edifice. The landslide cuts deeply into the island structure, and the scar exposures suggest an edifice that is dominated by loosely compacted layers of volcanic rock fragments.

    The landslide mass split and flowed around a remnant block of the island and dispersed within the channel between Umboi and Sakar (Figure 1), where it formed a deposit that is relatively flat at the margins and has irregular channelization in the central part. Parts of the landslide deposit traveled through a constriction between Umboi and Sakar and incorporated underlying seafloor sediment.

    A Framework for Future Models

    Our observations indicate that minor changes in slope gradient can strongly affect landslide dynamics. The deposition of the Ritter landslide entailed a progressive, multiphase, brittle to plastic failure that mobilized material over a considerable distance. The distal deposit, near the leading edge of the landslide, incorporates a major proportion of underlying seafloor sediment.

    Seismic profiles through the distal deposit indicate that the 1888 landslide was only the latest of a series of large-volume volcanic landslides from the surrounding islands. Some blocks piercing the seafloor are, in fact, rooted within older and much larger landslide deposits.

    How large a tsunami a volcanic collapse landslide of a given size will generate and how far the tsunami will travel before it dissipates remain open questions. The information we gathered on this expedition will provide the framework for coupled landslide-tsunami models, which are required to assess the destructive potential of sector collapse–related tsunamis.
    Acknowledgments

    This work reflects the joint effort of the SO252 expedition’s shipboard scientific party. We thank Simon Day, Eli Silver, and Russell Perembo for sharing data and helping with the survey planning. We thank the master and crew of R/V Sonne and our technicians for support during the cruise. Data collection was funded through the BMBF project Ritter Island 03G0252A. A.M. acknowledges funding from the European Research Council under the European Union’s Horizon 2020 Programme (MARCAN, grant agreement 677898).

    References

    Baldwin, S. L., P. G. Fitzgerald, and L. E. Webb (2012), Tectonics of the New Guinea region, Annu. Rev. Earth Planet. Sci., 40, 495–520, https://doi.org/10.1146/annurev-earth-040809-152540.

    Day, S., et al. (2015), Submarine landslide deposits of the historical lateral collapse of Ritter Island, Papua New Guinea, Mar. Pet. Geol., 67, 419–438, https://doi.org/10.1016/j.marpetgeo.2015.05.017.

    Johnson, R. (2013), Fire Mountains of the Islands: A History of Volcanic Eruptions and Disaster Management in Papua New Guinea and the Solomon Islands, ANU Press, Acton, Australia, https://doi.org/10.26530/OAPEN_462202.

    Ward, S. N., and S. Day (2003), Ritter Island volcano—Lateral collapse and the tsunami of 1888, Geophys. J. Int., 154, 891–902, https://doi.org/10.1046/j.1365-246X.2003.02016.x.

    Author Information

    Aaron Micallef, Marine Geology and Seafloor Surveying group, University of Malta, Msida; Sebastian F. L. Watt, School of Geography, Earth and Environmental Sciences, University of Birmingham, U.K.; Christian Berndt (email: cberndt@geomar.de) and Morelia Urlaub, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany; Sascha Brune, GFZ German Research Centre for Geosciences, Potsdam; and Ingo Klaucke, Christoph Böttner, Jens Karstens, and Judith Elger, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany
    Citation: Micallef, A., S. F. L. Watt, C. Berndt, M. Urlaub, S.Brune, I. Klaucke, C. Böttner, J. Karstens, and J. Elger (2017), An 1888 volcanic collapse becomes a benchmark for tsunami models, Eos, 98, https://doi.org/10.1029/2017EO083743. Published on 10 October 2017.

    See the full article here .

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

     
  • richardmitnick 5:10 am on November 23, 2016 Permalink | Reply
    Tags: , , , Tsunamis   

    From COSMOS: “Gravity shifts could sound early earthquake alarm” 

    Cosmos Magazine bloc

    COSMOS

    23 November 2016
    No writer credit found

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    The 2011 Tohoku-Oki earthquake generated tsunamis that devastated large swathes of Japan, including the Fukushima Nuclear Power Plant. A new earthquake detection technique might help give residents a few minutes’ extra warning. XINHUA / Gamma-Rapho / Getty Images

    As deep rock shuffles around, an area’s gravitational pull changes too. Detecting these blips could provide precious minutes when it comes to tsunami warnings.

    Earthquakes can shuffle around huge chunks of the deep Earth. But picking up these signs by measuring the associated transient gravity change might help provide early warnings, new research shows.

    Jean-Paul Montagner from the Paris Institute of Earth Physics in France and colleagues examined data collected during the devastating 2011 Tohoku-Oki earthquake off the coast of Japan, and detected a distinct gravity signal that arose before the arrival of the seismic waves. They published their work in Nature Communications.

    And while the technology to employ their system is not yet set up, they say the technique may herald new developments in early warning systems for earthquake hazards such as tsunamis.

    Earthquakes are notoriously hard to predict. When a fault line ruptures, seismic waves travel through and around the Earth and these are usually the first sign that at earthquake has hit.

    And even though these waves travel quickly – the fastest, P-wave or primary waves, can barrel through the Earth at 13 kilometres per second – they still mean precious seconds or minutes before the waves arrive at a seismic station.

    Montagner and his crew thought there could be a way to detect an earthquake before the waves appeared.

    Seismologists have known for more than a decade that there are static gravity changes following a rupture. This happens because as a fault line moves around, mass is redistributed below the surface. This means some areas suddenly become less dense while others pack on mass – and so their gravitational pull changes too.

    Such changes are measured with gravimeters. The problem is there’s background noise when it comes to gravity changes – the dynamic Earth constantly shifts and wriggles. Could the sudden gravity signal associated with an earthquake be teased out from the underlying noise?

    To find out, the researchers needed to examine a large earthquake that happened close enough to a sensitive gravimeter, so small changes in the gravity field could be picked up, but far enough away so the P-waves didn’t immediately reach seismic sensors.

    They found an ideal example in the 11 March Tohoku-Oki earthquake that led to the Fukushima Nuclear Power Plant disaster.

    Some 500 kilometres from the earthquake’s epicentre was a gravimeter at the Kamioka Observatory. The observatory was surrounded by five seismic stations. P-waves from the earthquake took around 65 seconds to reach the stations.

    Montagner and his colleagues first “calibrated” their statistical technique with 60 days of background gravity measurements – from 1 March 2011 to 5.46am on 11 March (21 seconds before the earthquake rumbled), then from 12 March to 30 April.

    They compared this background with measurements taken during the earthquake and shortly thereafter, and found a distinct blip at the time of the earthquake. It was small, but strong enough to be distinguished from the background with 99% confidence.

    So can this prediction technique be implemented today? Unfortunately not – it would require building a substantial network of exceptionally sensitive gravimeters which don’t yet exist. But, the researchers write, they could have the potential to let seismologists estimate earthquake magnitude quickly – a process that currently takes up to several minutes.

    See the full article here .

    You, too, can help with earthquake knowledge and research.

    QCN bloc

    Quake-Catcher Network

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

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

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

    BOINCLarge

    BOINC WallPaper

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

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

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

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

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

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

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

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

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  • richardmitnick 7:19 am on July 18, 2016 Permalink | Reply
    Tags: , , , Tsunamis,   

    From UCSD via Science: “These disaster machines could help humanity prepare for cataclysms” 

    AAAS

    AAAS

    UC San Diego bloc

    Jul. 14, 2016
    Warren Cornwall

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    The “Wall of Wind” at Florida International University in Miami can blow as fiercely as a category-5 hurricane. Robert Sullivan

    For the past year, Tara Hutchinson has been trying to figure out what will happen to a tall building made from thin steel beams when “the big one” hits.

    To do that, she has erected a six-story tower that rises like a lime-green finger from atop a shrub-covered hill on the outskirts of San Diego, California. Hundreds of strain gauges and accelerometers fill the building, so sensitive they can detect wind gusts pressing against the walls. Now, Hutchinson just needs an earthquake.

    In most of the world, this would be a problem. Even here, where a major fault runs right through downtown, the last quake of any note struck 6 years ago and was centered in nearby Mexico. But Hutchinson, a structural engineering professor at the University of California (UC), San Diego, doesn’t need plate tectonics to cooperate. This summer she has an appointment at one of the world’s biggest earthquake machines.

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    6 Story CFS Load Bearing Project Downtown Los Angeles – Wilshire Vermont (Topping out Roof). http://nheri.ucsd.edu/projects/2016-light-gauge-cold-steel-buildings/

    This device—a sort of bull ride for buildings—is one in a network built around the United States over the past 15 years to advance natural disaster science with more realistic and sophisticated tests. Costing more than $280 million, the National Science Foundation (NSF) initiative has enabled scientists to better imitate some of the most powerful and destructive forces on Earth, including earthquakes, tsunamis, and landslides.

    The work has led to new building standards and better ways to build or retrofit everything from wharves to older concrete buildings. Scientists have gained insights into how quakes damage pipes in walls and ceilings and how to help quake-proof highway ramps, tall steel buildings, parking garages, wooden homes, and brick walls, to name a few.

    That expansion continues today. In a new $62 million, 5-year program, the network of doomsday machines is expanding to simulate hurricanes and tornadoes and is joining forces with computer modeling to study how things too big for a physical test, such as nuclear reactors or an entire city, will weather what Mother Nature throws at them.

    Scaling down disasters

    Credit California’s Northridge earthquake for helping set this in motion. The 1994 quake, centered near Los Angeles, killed 72 and cost an estimated $25 billion in damages. In its aftermath, a report commissioned by Congress warned that the country needed a more systematic approach to studying how to reduce damage from earthquakes. NSF responded with the $82 million Network for Earthquake Engineering Simulation. The money funded a construction spree at 14 sites around the country. Another $200 million paid for operating the sites through 2014. That included UC San Diego, which unveiled the world’s largest outdoor shake table in 2004.

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    A building awaits its ordeal on the shake table at the University of California, San Diego. Erik Jepsen/UC San Diego

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    Researchers at Oregon State University, Corvallis, unleash tsunamis in a wave basin. © Aurora Photos/Alamy Stock Photo

    Descriptions of these disaster labs are often couched in superlatives: the biggest, the longest, the most powerful. In addition to the San Diego facility, the projects funded under the original program and its successor, the Natural Hazards Engineering Research Infrastructure (NHERI), include North America’s largest wave flume for studying tsunamis at Oregon State University, Corvallis; the world’s largest university-based hurricane simulator at Florida International University in Miami; and, at UC Davis, the world’s biggest centrifuge for making scale models mimic the stresses on tons of buildings, rock, and dirt—crucial information for assessing how structures will weather earthquakes and landslides.

    More than bragging rights is at stake. When it comes to learning how buildings cope with the forces generated in a natural disaster, size often does matter. For example, the way soil particles stick together, an important factor in landslide risks, depends on how much mass is pushing down on them. Similarly, it’s nearly impossible to build accurate, tiny versions of rebar: steel rods embedded in concrete structures that are critical to building performance. Similar difficulties arise with measuring how hurricane-force winds interact with a building.

    “You can’t take a real building and scale it down to one-tenth and put it in a wind tunnel. The physics doesn’t work,” says Forrest Masters, a wind engineer at the University of Florida in Gainesville who directs his university’s share of NHERI. That includes a machine capable of subjecting 5-meter-tall walls to the air pressures found in a 320-kilometer-per-hour hurricane, and a wind tunnel whose floor can be modified to see how different terrain influences the way wind interacts with structures.

    Computer models too can fall short in accurately reproducing all the forces at play as, say, a bridge twists and sways in an earthquake. So many different pieces in the bridge are pulled in so many directions at once that it can fail in unpredictable ways, causing models to misrepresent reality. In 2010, a contest at the San Diego shake table pitted 41 teams of experts running models against a real-life test of a 7-meter-tall bridge column topped with 236 metric tons of concrete blocks. The computer results were all over the place, says Stephen Mahin, a structural engineer at UC Berkeley who helped orchestrate the event. On average, they underestimated how much the column would sway by 25%. “You can’t quite trust the computer results yet,” Mahin says.

    One morning in mid-May, Hutchinson inspects her building in the final stages of preparation for the test. She points to tiny gaps that have sprung open where metal ceiling joists meet the wall in a first-floor room. That happened during a minor, preliminary shake her team delivered to the building a day earlier. It’s the kind of thing that could make a difference in how load is shared between pieces of the building, and how much damage the building suffers in the next temblor. And it wouldn’t show up in a computer model.

    “You’re not going to account for every screw,” she says. “Look at how subtle this damage is.”

    Shake, rattle, and roll

    Devising a machine that can pack the same wallop as a magnitude-8.0 earthquake or a category-5 hurricane isn’t easy, or cheap. A look under the hood of San Diego’s shake table illustrates the kind of mechanical muscle needed. Joel Conte, an engineering professor who oversees the shake table operations, leads the way into a cavernous under-ground room filled with machinery. A 20,000- liter metal tank holds the hydraulic fluid that drives the entire system. Two pumps slurp the fluid from there into a bank of 50 slender black cylinders reminiscent of street light poles at pressures reaching 34,000 kilopascals (5000 pounds per square inch). That high pressure is crucial, generating enough force to swiftly move an entire building.

    Conte turns down a passageway, tracing the path of the fluid through steel pipes 30 centimeters across, and into a room dominated by a mass of steel resembling the hull of a flat-bottomed boat. This is the epicenter. A metal plate 5 centimeters thick, 12 meters long, and nearly 8 meters wide sits overhead, bolted to the steel underbelly. At either end, an actuator that looks something like a car’s shock absorber, but is as thick as a man’s torso, extends from this structure to the concrete wall. When the commands come from computers in a nearby building, the actuators will jerk to life, the hydraulic fluid driving them back and forth. The plate, pushed and pulled between them, will slide across metal sheets polished mirror-smooth at speeds of up to 1.8 meters per second. Voilà! Instant quake.

    “The real world, you cannot count on it,” Conte says. “You cannot say, ‘Oh, I’m going to sit and wait for the next earthquake in front of this big building, and I’m going to invest a lot in sensors.’ You may have to wait 30, 40, 50 years. So you produce an earthquake.”

    Since its construction for $10 million, the shake table has tested a four-story concrete parking garage, a wind turbine, and a five-story concrete building complete with elevator and stairs, among other things. The tests have shown that special inserts can increase resilience by allowing a building to move over its foundation and that modular concrete floors can behave erratically unless they have additional reinforcement. They have also revealed how tall, wood-framed buildings fail and how reinforcements can strengthen old brick buildings.

    Back in his office, Conte gleefully clicks through the “best of” video highlights. A four-story wood building twists and splinters to the ground. A parking garage teeters back and forth like a rocking chair. A split screen shows two identical rooms filled with hospital beds and medical equipment. One is in a building outfitted with padded foundations that help it absorb an earthquake’s shock; the other isn’t. As the video runs, beds in the regular building suddenly lurch back and forth before toppling over. In the other, they barely move.

    In the current test, Hutchinson wants to see how a building six stories tall made from lightweight steel performs during and after an earthquake. She thinks it could do well, partly because it’s lighter than a concrete building of the same height, giving it less mass to generate damaging forces during a quake. Today, building codes allow this type of construction to be just shy of 20 meters tall. But the tallest building really put to the test was only two stories high.

    The structure, modeled after an apartment building, is destined for a multistage torture test. Hutchinson and her colleagues will first put it through a simulation of several quakes, including Northridge and a 2010 magnitude-8.8 in Chile. Then they will set fires in parts of the building to see how it holds up in a blaze triggered by quake damage. Then they will shake the building again in a mock aftershock, hard enough that it might collapse.

    The results aren’t just of academic interest. Sponsors of the test include manufacturers of the steel construction parts, the insurance industry, and state government. “There’s nothing like a full-scale test,” says Richard McCarthy, executive director for the Cali–fornia Seismic Safety Commission in Sacramento, a government commission that advises policymakers. It contributed $100,000 to the event, he says, partly with an eye toward potential changes to building codes governing construction using these materials.

    Conte is now lobbying state officials for a $14 million upgrade that would allow the machine to run even more realistic tests. Right now it can move only back and forth in two directions; new hardware would add up-and-down, side-to-side, and diagonal motions, enabling it to move in every direction—like the world’s biggest shake table, an indoor facility in Miki, Japan.

    Up next: Hybrid simulations

    Scientists are trying to go even bigger by marrying such physical tests with computer models. The resulting “hybrid” simulations can test massive structures too big to fit inside any test facility, says James Ricles, a civil engineer at Lehigh University in Bethlehem, Pennsylvania. His lab, which is part of the NSF network, tests well-understood parts of a structure with computer models but stages physical tests for parts that the models can’t handle. In a feedback loop measured in milliseconds, sensors from the physical test send data to the model, which adapts and sends new signals that tell the machines driving the physical test how to tweak their next moves.

    Ricles’s lab simulated the behavior of an elevated highway during an earthquake by physically testing the concrete columns while testing a virtual model of the bridge deck in a computer. He recently applied the same strategy to testing a design meant to allow a steel building to rock back and forth rather than bend during a quake. A four-story chunk of the building stood in the lab; the rest of it existed only in the microprocessors of a computer.

    Destruction is a definite part of the work’s appeal, says Gilberto Mosqueda, an engineering professor who runs hybrid tests at UC San Diego: “You build these models, and essentially you shake them till you break them.” But the mountains of data generated by the tests also open the way to more sophisticated numerical models that could one day do some of the work of the doomsday machines.

    Whereas the earlier NSF program focused on big testing platforms, the NHERI initiative is putting more money into the virtual side. The University of Texas, Austin, won $13.7 million to build a data repository and software platform to store information from years of field tests. In the future, engineers should be able to tap data in the digital repository to boost the accuracy of their computer models. And NSF will soon issue an $11 million award for a computational modeling and simulation center.

    “Will we get to the point where we can just model everything and have confidence? That may still be a long way off,” says Joy Pauschke, a structural engineer and director of the NSF program that funds the testing work in Arlington, Virginia. “But hopefully as we test and improve models, we start moving towards having better capabilities with the computational modeling.”

    Berkeley’s Mahin—whose 2010 contest exposed the shortcomings of models—now also foresees bright prospects for modeling. Advances in machine learning and cloud computing, he predicts, will lead to models capable of simulating not just single buildings but entire communities. Unleashing “virtual disasters” could then enable researchers and government officials to grasp the region-wide effects of a major quake or storm and decide which measures today would prevent the most damage.

    “In 20 years, you can model a whole city in a very complicated way, I think,” Mahin says. “There’s a great hope this analysis can help mitigate the damage from future natural disasters.”

    See the full article here .

    ______________________________________________________________________________________

    Earthquake and Post-Earthquake Fire Performance of Mid-Rise Light-Gauge Cold-Formed Steel Framed Buildings

    Abstract: Light-gauge cold-formed steel (CFS) framed multi-story residential housing has the potential to support societies urgent need for low cost, multi-hazard resilient housing. CFS-framed structures offer lower installation and maintenance costs, are durable, ductile, lightweight, and manufactured from recycled materials. In addition, consistency in material behavior and low material costs are added benefits compared with their wood-framing counterparts. The components of CFS-framed assemblies (studs, track, joists) can be assembled quickly and with relative ease into prefabricated panels. Notably, the ductile nature of a CFS-framed structure aligns with the performance needs in moderate to high seismic zones. Compared to other lightweight framing solutions (such as timber), CFS is non-combustible, an important basic characteristic to prohibit fire spread. Taken in totality, these many beneficial attributes lead to a highly sustainable infrastructure for housing communities.

    This research aims to evaluate the earthquake and post-earthquake fire performance of mid-rise CFS-building systems through full-scale earthquake and live thermal testing of a 6-story wall-braced system. Through partnership with cold-form steel and other materials suppliers, design engineers, and insurance entities, a unique experimental program is underway. Central to this effort is the construction of a full-scale portion of a 6-story CFS-wall braced building directly on the UCSD Large High Performance Outdoor Shake Table. Wall and floor systems for the building are assembled in a panelized fashion off-site, thus the overall erection time of the building is dramatically reduced. The test building will be subjected to low amplitude white noise motions and sequentially increasing in amplitude earthquake motions. Subsequently, live thermal tests will be conducted on two floors of the building, in corridor and room like spaces strategically designed to investigate thermal patterns that develop due to reduced compartmentation ensued during the earthquake motions.

    5

    Investigators
    Prof. Tara Hutchinson (PI)
    Prof Gil Hegemeir (Co-PI)
    Dr. Xiang Wang (Post-Doctoral Researcher)
    Mr. Srikar Gunisetty (Graduate Student) [UC San Diego]
    Prof. Brian Meacham [WPI]
    Dr. Praveen Kamath [WPI]

    Sponsors
    Department of Housing and Urban Development, California Seismic Safety Commission, and more than 10 industry sponsors (see: http://cfs-research.ucsd.edu)

    See this full article here .

    ______________________________________________________________________________________

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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  • richardmitnick 3:10 pm on May 13, 2016 Permalink | Reply
    Tags: , , Tsunamis,   

    From U Hawaii: “Probability of Aleutians mega-earthquake estimated” 

    U Hawaii

    University of Hawaii

    May 13, 2016
    Marcie Grabowski

    1
    The map showing the Aleutians with respect to Hawaiʻi. The red and yellow arcs indicate the sections of the Aleutian subduction zones considered in the probability analysis. Stars and dates indicate epicenters of prior 20th century great earthquakes (Mw > 8). (credit: Butler et al., 2016)

    A team of researchers from the University of Hawaiʻi at Mānoa published* a study this week that estimated the probability of a magnitude 9+ earthquake in the Aleutian Islands—an event with sufficient power to create a mega-tsunami especially threatening to Hawaiʻi. In the next 50 years, they report, there is a 9 percent chance of such an event. An earlier State of Hawaiʻi report (PDF) (Table 6.12) has estimated the damage from such an event would be nearly $40 billion, with more than 300,000 people affected.

    Earth’s crust is composed of numerous rocky plates. An earthquake occurs when two sections of crust suddenly slip past one another. The surface where they slip is called the fault, and the system of faults comprises a subduction zone. Hawaiʻi is especially vulnerable to a tsunami created by an earthquake in the subduction zone of the Aleutian Islands.

    Back to basics

    “Necessity is the mother of invention,” said Rhett Butler, lead author and geophysicist at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). “Having no recorded history of mega tsunamis in Hawaiʻi, and given the tsunami threat to Hawaiʻi, we devised a model for magnitude 9 earthquake rates following upon the insightful work of David Burbidge** and others.”

    Butler and co-authors Neil Frazer (SOEST) and William Templeton (now at Portland State University) created a numerical model based only upon the basics of plate tectonics: fault length and plate convergence rate, handling uncertainties in the data with Bayesian techniques.

    Using the past to inform the future

    To validate this model, the researchers utilized recorded histories and seismic/tsunami evidence related to the 5 largest earthquakes (greater than magnitude 9) since 1900 (Tohoku, 2011; Sumatra-Andaman, 2004; Alaska, 1964; Chile, 1960 and Kamchatka, 1952).

    “These five events represent half of the seismic energy that has been released globally since 1900,” said Butler. “The events differed in details, but all of them generated great tsunamis that caused enormous destruction.”

    To further refine the probability estimates, they took into account past (prior to recorded history) tsunamis—evidence of which is preserved in geological layers in coastal sediments, volcanic tephras, and archeological sites.

    “We were surprised and pleased to see how well the model actually fit the paleotsunami data,” said Butler.

    Mitigating the risk

    Using the probability of occurrence, the researchers were able to annualize the risk. They report the chance of a magnitude 9 earthquake in the greater Aleutians is 9 percent ± 3 percent in the next 50 years. Hence the risk is 9 percent of $40 billion, or $3.6 billion. Annualized, this risk is about $72 million per year. Considering a worst-case location for Hawaiʻi limited to the Eastern Aleutian Islands, the chances are about 3.5 percent in the next 50 years, or about $30 million annualized risk. In making decisions regarding mitigation against this $30-$72 million risk, the state can now prioritize this hazard with other threats and needs.

    The team is now considering ways to extend the analysis to smaller earthquakes, magnitude 7–8, around the Pacific.

    1
    The only well-documented paleotsunami deposit in Hawaiʻi from the 16th century is on Kauaʻi. The Makauwahi sinkhole, on the side of a hardened sand dune, is viewed toward the southeast from an apparent altitude of 342 m. Inset photos show two of the wall edges, indicating the edges of the sinkhole. The east wall, left, is 7.2 m above mean sea level and about 100 m from the ocean. Note for scale the people in the right image. (photo credits: R. Butler, left, Gerard Fryer, right, GoogleMaps, background and figure from Butler et al., 2014)

    *Science paper:
    Bayesian Probabilities for Mw 9.0+ Earthquakes in the Aleutian Islands from a Regionally Scaled Global Rate

    **Science paper:
    A Probabilistic Tsunami Hazard Assessment for Western Australia

    See the full article here .

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    System Overview

    The University of Hawai‘i System includes 10 campuses and dozens of educational, training and research centers across the Hawaiian Islands. As the public system of higher education in Hawai‘i, UH offers opportunities as unique and diverse as our Island home.

    The 10 UH campuses and educational centers on six Hawaiian Islands provide unique opportunities for both learning and recreation.

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  • richardmitnick 10:17 am on May 10, 2016 Permalink | Reply
    Tags: , , , Slow-slip events, Tsunamis   

    From Eos: “Undersea Data Tie Slow Fault Slip to Tsunami-Causing Quakes” 

    Eos news bloc

    Eos

    6 May 2016
    JoAnna Wendel

    1
    Scientists deploy an ocean bottom seismometer and absolute pressure gauge offshore of Gisborne, New Zealand, from the R/V Tangaroa. Credit: Takeo Yagi, University of Tokyo

    Recent monitoring of the seafloor off the coast of New Zealand has revealed that episodes of slow rupture of Earth’s crust can occur in the same shallow portion of a fault zone where tsunami-generating earthquakes originate. The new finding deepens scientists’ suspicions that the type of slow-motion, or “silent,” earthquake that the researchers detected, known as a slow-slip event, may signal or even trigger the onset of tsunami-generating earthquakes.

    “There seems to be a link potentially with where these really shallow slow slip events happen and where tsunami-generating earthquakes happen,” said Laura Wallace, a research scientist at the University of Texas at Austin. Wallace is the lead author on a paper* published yesterday in Science about the new observations.

    In undersea trenches in many parts of the world, one of the Earth’s tectonic plates pushes beneath another, or subducts, in an inching, lurching process that builds up stress in the subduction zone that can catastrophically release as an earthquake, which in turn can trigger a tsunami.

    The tectonic plates of the world were mapped in 1996, USGS.
    The tectonic plates of the world were mapped in 1996, USGS

    However, in slow-slip events that are common at subduction zones, sliding of the plates at a more rapid pace than usual (although still much slower than the sudden shift of an earthquake) relieves stress in the fault zone over a period of typically days to months.

    In the new research, Wallace and her colleagues studied a subduction zone called the Hikurangi margin off the east coast of New Zealand’s North Island, where the Pacific Plate slowly slides under the Australian Plate. In 1947, two earthquakes at shallow depths within this margin sent tsunamis crashing onto New Zealand’s shore, damaging buildings and roads.

    Slowly Slipping Plate

    Scientists have long tracked tectonic plate movements at subduction zones—for example, in Japan, Costa Rica, and the U.S. Pacific Northwest—by using land-based GPS monitors on the overlying plate that can detect motions deep below. However, gathering data on plate behavior at the relatively shallow, undersea trench that lies offshore and is where the leading edge of the overlying plate meets the subducting plate has proven to be a difficult task requiring other sorts of sensors. GPS observations typically reveal slow-slip events in subduction zones at depths 25–50 kilometers deeper than the trench, Wallace said.

    Onshore near the Hikurangi margin, GPS measurements have shown that slow-slip events occur roughly every 18 months, the larger ones taking place once every 4–5 years, according to Wallace. To find out if slow slip could be observed at shallow depths and offshore near the trench, she and her team picked a yearlong window of time when they would mostly likely detect a slow-slip event. Then, in May 2014, they deployed an array of 15 ocean bottom seismometers and 24 seafloor pressure gauges on the seafloor to record possible events.

    Between May 2014 and June 2015, the pressure detectors revealed vertical movements of the ocean floor by, in essence, weighing the overlying water column: Higher pressure meant that the seafloor sank and more water pressed down, whereas a lower pressure indicated a rising seafloor, which displaced water and decreased the pressure.

    After analyzing the data, the researchers found a slow-slip event that lasted 2 weeks and moved the seafloor upward 1.5–5.5 centimeters—a vertical movement associated with 15–20 centimeters total slippage along the plate boundary. That shift equates to 3 to 4 years of normal plate movement, Wallace said.

    The newly revealed slow-slip rupture took place in the same shallow portion of the subduction zone where the 1947 tsunami-generating earthquakes had originated. If this slip had occurred suddenly, rather than over the course of 2 weeks, it would have clocked in as a magnitude 6.8 earthquake, the researchers report.

    “Our results clearly show that shallow, slow-slip event source areas are also capable of hosting seismic rupture and generating tsunamis,” said Yoshihiro Ito of Kyoto University in Japan, who coauthored the study.

    Future Earthquake Monitoring

    Earlier this year, another Science paper reported that slow-slip events often occurred before an earthquake of magnitude 5 or higher hit. In fact, a swarm of slow-slip events preceded the devastating 9.0 magnitude earthquake and tsunami that hit Japan in 2011.

    Scientists have typically detected slow slip at subduction zones at tens of kilometers beneath the trench, where temperatures reach 350°C–450°C and pressures are high, Wallace said. They suspected that slow-slip events also occurred in shallower regions of trenches, less than 10–15 kilometers deep, where pressures and temperatures are lower and tsunami-generating earthquakes originate.

    The new findings indicate that slow-slip events can, indeed, happen “over a massive range of conditions,” from warm temperatures and high pressures within the crust to shallow locations, cooler crustal temperatures, and lower pressures, Wallace continued. “This is important to know because we don’t really understand yet why these slow-slip events happen.” She added that slow-slip events might trigger earthquakes in a subduction zone by providing stress relief in one area that causes stress buildup somewhere else, leading to a sudden rupture.

    “These data should aid in better understanding these somewhat enigmatic shallow tsunami earthquakes,” said Roland Burgmann, a seismologist at University of California, Berkeley, who wasn’t involved in the research.

    Wallace and her colleagues plan to investigate the Hikurangi margin in the future by drilling into the seafloor to figure out what causes slow-slip events in the first place.

    Having now observed slow slip close to the epicenter of the 1947 earthquake underscores the need for monitoring, Wallace said, “because there’s potential for a slow-slip event to trigger an earthquake that could generate a big tsunami.”

    —JoAnna Wendel, Staff Writer

    Editor’s Note, 6 May 2015: For a detailed look at research efforts off New Zealand’s coast that led to the results described above, read the Eos.org project update.

    Citation: Wendel, J. (2016), Undersea data tie slow fault slip to tsunami-causing quakes, Eos, 97, doi:10.1029/2016EO051993. Published on 6 May 2016.

    © 2016. The authors. CC BY-NC-ND 3.0

    *Science paper:
    Slow slip near the trench at the Hikurangi subduction zone, New Zealand

    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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