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Tectonic Plates Reverse Their Movement Before Major Earthquakes
By Fabian Schmidt
Researchers have discovered an interesting similarity in two of the largest recent earthquakes in Japan and Chile: a strange large-scale ground movement back and forth in the months leading up to the quake.
These earthquakes are among the 10 strongest ever measured: the 2011 Tohoku-oki seaquake off the coast of Japan registered 9.0 on the moment magnitude scale, triggering the devastating tsunami that destroyed the Fukushima Nuclear Power Plant. It was the fourth-strongest quake in the last 100 years. The 2010 seaquake off the coast of the Maule region of Chile, occupies sixth place on the list.
Researchers from the Geoforschungszentrum Potsdam (GFZ) along with collaborators from Chile and the United States have now discovered astonishing similarities in the months before both quakes: multiple strange reversals of ground motion — an extremely slow "wobbling" of the continental plate, so to speak.
Lead author, geophysicist Jonathan Bedford, along with a team of geodesists, geologists and seismologists, evaluated the movements of ground stations of the Global Navigation Satellite System (GNSS).
These ground stations continuously track the distances to multiple GNSS satellites that orbit the earth in elliptical orbits. After these distances have been established, and given the estimates of the satellite positions, geodesists are able to define the motion of points on the Earth within a terrestrial reference frame.
In Japan, there is a very dense network of ground stations. Although the network in Chile was not as dense in 2010, it was sufficient to obtain the data.
Whole Continental Plate 'Wobbles'
Bedford and his colleagues analyzed how the ground stations in Japan and Chile had moved in the five years before the two quakes. They noticed that the motion of the continental plate on which the stations are located had been reversed several times in the last five months before the quake (in the case of Japan) and seven months (in the case of Chile). The researchers published their results in the scientific journal Nature.
Both plate boundaries are subduction zones. Subduction is the process of one plate diving under another. In both study regions, the oceanic plates are subducting underneath the continental plates and meet at a place called the trench, which for both cases is submerged under the ocean. Normally, the continental plate is pressed by the oceanic plate and thus pushed away from the trench. However, the geophysicists have now discovered that this movement was first reversed in the direction of the trench, then away from the trench, then back towards the trench again.
Same Movement Over Thousands of Kilometers
They call this phenomenon "wobbling," due to its appearance in the GNSS time series. The amplitude of this movement is not particularly great — it was only between 4 and 8 millimeters — but Bedford points out that this is significant compared to the relative plate motion that can be a few centimeters per year. Furthermore, the spatial extent of the signal extended thousands of kilometers along the plate boundaries.
"It is a common assumption that deeper subduction proceeds at a fairly constant speed in between large earthquakes," says Bedford. "Our study shows that this assumption is an oversimplification. In fact, its variability might be a key factor in understanding how the largest earthquakes nucleate."
With global satellite tracking now becoming better and better, and with accurate data available for the first time in decades, earthquake researchers have an ever-increasing ability to make such observations.
"We can now trace movements back decades," says Bedford. "In the next stage, we'd like to monitor the changes in near real time."
Not Suitable as an Early Warning System
Until now, seismologists have been more able to say where large earthquakes are likely to occur — less able to say when. By simply calculating the magnitude of the last large earthquake in a region and knowing the average relative plate velocity, one can estimate when that fault will be mature enough to sustain a repeat event, although there are great uncertainties in this approach. This is because sometimes a fault will rupture only over a smaller area (e.g. with a "large" magnitude 8 event) and other times it will rupture over many magnitude 8 regions all at once (e.g. in a "mega" magnitude 9 event).
Could an observed untypical plate movement therefore give us a better warning of an imminent earthquake? Not really.
"It would not be wise for a geophysicist to issue such a warning," is Bedford's sobering answer. "The observed signals of this study are not necessarily precursory movements of a major quake."
More research is necessary and as a matter of principle, people in known earthquake areas should not let their guard down.
"The general public should always be prepared," Bedford warns.
Reposted with permission from Deutsche Welle.
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By Gwen Ranniger
In the midst of a pandemic, sales of cleaning products have skyrocketed, and many feel a need to clean more often. Knowing what to look for when purchasing cleaning supplies can help prevent unwanted and dangerous toxics from entering your home.
1. Fragrance – Avoid It<p>One of the fastest ways to narrow down your product options is immediately eliminating any product that promotes a fragrance, or parfum. That scent of "fresh breeze" or lemon might initially smell good, but the fragrance does not last. What does last? The concoction of various undisclosed and unregulated chemicals that created that fragrance.</p><p>Many fragrances contain phthalates, which are linked to many health risks including reproductive problems and cancer.</p>
2. With Bleach? Do Without<p>Going scent-free should have narrowed down your options substantially – now, check the front of the remaining packaging. Any that include ammonia or chlorine bleach ought to go, as these substances are irritating and corrosive to your body. While bleach is commonly known as a powerful disinfectant, there are safer alternatives that you can use in your home, such as sodium borate or hydrogen peroxide.</p><p>While you're at it, check if there are any warnings on the label – "flammable," "use in ventilated area," etc. – if the product is hazardous, that's a red flag and should be avoided.</p>
3. Check the Back Label<p>Flip to the back of the remaining contenders and check out that ingredient list. Less is more, here. Opt for a shorter ingredient list with words you recognize and/or can pronounce.</p><p>You may notice many products do not have ingredient lists – while this doesn't necessarily mean they contain toxic ingredients, transparency is key. Feel free to look up a list online, or stick to products that are open about their ingredients.</p>
4. Ingredients to Avoid<p>We already mentioned that cleaners containing fragrance or parfum, and bleach or ammonia should be avoided, but there are other ingredients to look out for as well.</p><ul><li>Quaternary ammonium "quats" – lung irritants that contribute to asthma and other breathing problems. Also linger on surfaces long after they've been cleaned.</li><li>Parabens – Known hormone disruptor; can contribute to ailments such as cancer</li><li>Triclosan – triclosan and other antibacterial chemicals are registered with the EPA as pesticides. Triclosan is a known hormone disruptor and can also impact your immune system.</li><li>Formaldehyde – Causes irritation of eyes, nose, and throat; studies suggest formaldehyde exposure is linked with certain varieties of cancer. Can be found in products or become a byproduct of chemical reactions in the air.</li></ul>
Cleaning Products and Toxics: The Bottom Line<p>Do your research. There are many cleaning products available, but taking these steps will drastically reduce your options and help keep your home toxic-free. Protecting your home from bacteria and viruses is important, but make sure you do so in a way that doesn't introduce other health risks into the home.</p><p><em>Reposted with permission from </em><em><a href="https://www.ehn.org/how-to-shop-for-cleaning-products-while-avoiding-toxics-2648130273.html" target="_blank">Environmental Health News</a>. </em><a href="https://www.ecowatch.com/r/entryeditor/2649054624#/" target="_self"></a></p>
JasonOndreicka / iStock / Getty Images
Twenty-five years ago, a food called Tofurky made its debut on grocery store shelves. Since then, the tofu-based roast has become a beloved part of many vegetarians' holiday feasts.
By Jessica Corbett
A leading environmental advocacy group marked Native American Heritage Month on Wednesday by urging President-elect Joe Biden, Vice President-elect Kamala Kamala Harris, and the entire incoming administration "to honor Indigenous sovereignty and immediately halt the Keystone XL, Dakota Access, and Line 3 pipelines."
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Returning the ‘Three Sisters’ – Corn, Beans and Squash – to Native American Farms Nourishes People, Land and Cultures
By Christina Gish Hill
Historians know that turkey and corn were part of the first Thanksgiving, when Wampanoag peoples shared a harvest meal with the pilgrims of Plymouth plantation in Massachusetts. And traditional Native American farming practices tell us that squash and beans likely were part of that 1621 dinner too.
Abundant Harvests<p>Historically, Native people throughout the Americas bred indigenous plant varieties specific to the growing conditions of their homelands. They selected seeds for many different traits, such as <a href="https://emergencemagazine.org/story/corn-tastes-better/" target="_blank" rel="noopener noreferrer">flavor, texture and color</a>.</p><p>Native growers knew that planting corn, beans, squash and sunflowers together produced mutual benefits. Corn stalks created a trellis for beans to climb, and beans' twining vines secured the corn in high winds. They also certainly observed that corn and bean plants growing together tended to be healthier than when raised separately. Today we know the reason: Bacteria living on bean plant roots pull nitrogen – an essential plant nutrient – from the air and <a href="http://www.tilthalliance.org/learn/resources-1/almanac/october/octobermngg" target="_blank" rel="noopener noreferrer">convert it to a form that both beans and corn can use</a>.</p><p>Squash plants contributed by shading the ground with their broad leaves, preventing weeds from growing and retaining water in the soil. Heritage squash varieties also had spines that discouraged deer and raccoons from visiting the garden for a snack. And sunflowers planted around the edges of the garden created a natural fence, protecting other plants from wind and animals and attracting pollinators.</p><p>Interplanting these agricultural sisters produced bountiful harvests that sustained large Native communities and <a href="http://dx.doi.org/10.1353/eam.2015.0016" target="_blank">spurred fruitful trade economies</a>. The first Europeans who reached the Americas were shocked at the abundant food crops they found. My research is exploring how, 200 years ago, Native American agriculturalists around the Great Lakes and along the Missouri and Red rivers fed fur traders with their diverse vegetable products.</p>
Displaced From the Land<p>As Euro-Americans settled permanently on the most fertile North American lands and acquired seeds that Native growers had carefully bred, they imposed policies that <a href="https://doi.org/10.1086/ahr/87.2.550" target="_blank">made Native farming practices impossible</a>. In 1830 President Andrew Jackson signed the <a href="https://guides.loc.gov/indian-removal-act" target="_blank">Indian Removal Act</a>, which made it official U.S. policy to force Native peoples from their home locations, pushing them onto subpar lands.</p><p>On reservations, U.S. government officials discouraged Native women from cultivating anything larger than small garden plots and pressured Native men to practice Euro-American style monoculture. Allotment policies assigned small plots to nuclear families, further limiting Native Americans' access to land and preventing them from using communal farming practices.</p><p>Native children were forced to attend boarding schools, where they had no opportunity to <a href="https://doi.org/10.5749/jamerindieduc.57.1.0145" target="_blank">learn Native agriculture techniques or preservation and preparation of Indigenous foods</a>. Instead they were forced to eat Western foods, turning their palates away from their traditional preferences. Taken together, these policies <a href="https://kansaspress.ku.edu/978-0-7006-0802-7.html" target="_blank" rel="noopener noreferrer">almost entirely eradicated three sisters agriculture</a> from Native communities in the Midwest by the 1930s.</p>
Reviving Native Agriculture<p>Today Native people all over the U.S. are working diligently to <a href="https://www.oupress.com/books/15107980/indigenous-food-sovereignty-in-the-united-sta" target="_blank" rel="noopener noreferrer">reclaim Indigenous varieties of corn, beans, squash, sunflowers and other crops</a>. This effort is important for many reasons.</p><p>Improving Native people's access to healthy, culturally appropriate foods will help lower rates of <a href="https://www.cdc.gov/vitalsigns/aian-diabetes/index.html" target="_blank">diabetes</a> and <a href="https://www.apa.org/pi/oema/resources/ethnicity-health/native-american/obesity" target="_blank">obesity</a>, which affect Native Americans at disproportionately high rates. Sharing traditional knowledge about agriculture is a way for elders to pass cultural information along to younger generations. Indigenous growing techniques also protect the lands that Native nations now inhabit, and can potentially benefit the wider ecosystems around them.</p>
By Jake Johnson
Amid reports that oil industry-friendly former Energy Secretary Ernest Moniz remains under consideration to return to his old post in the incoming Biden administration, a diverse coalition of environmental groups is mobilizing for an "all-out push" to keep Moniz away from the White House and demand a cabinet willing to boldly confront the corporations responsible for the climate emergency.