March 2019

Beneath Earth's Crust, Hot Rocks Creep as Oceanic Plates Plunge Toward the Core

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<tr><td class="tr-caption" style="text-align: center;">Cross-sections of Earth’s mantle down to 1,400 km depth showing changes in its flow as ancient ocean beds fall into Earth’s deep interior. Credit: Ana M. G. Ferreira et al.</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">As ancient ocean floors plunge over 1,000 km into the Earth's deep interior, they cause hot rock in the lower mantle to flow much more dynamically than previously thought, finds a new UCL-led study.</span><br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The discovery answers long-standing questions on the nature and mechanisms of mantle flow in the inaccessible part of deep Earth. This is key to understanding how quickly Earth is cooling, and the dynamic evolution of our planet and others in the solar system.<br />
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"We often picture the Earth's mantle as a liquid that flows but it isn't -- it's a solid that moves very slowly over time. Traditionally, it's been thought that the flow of rock in Earth's lower mantle is sluggish until you hit the planet's core, with most dynamic action happening in the upper mantle which only goes to a depth of 660 km. We've shown this isn't the case after all in large regions deep beneath the South Pacific Rim and South America," explained lead author, Dr Ana Ferreira (UCL Earth Sciences and Universidade de Lisboa).<br />
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"Here, the same mechanism we see causing movement and deformation in the hot, pressurised rock in the upper mantle is also occurring in the lower mantle. If this increased activity is happening uniformly over the globe, Earth could be cooling more rapidly than we previously thought," added Dr Manuele Faccenda, Universita di Padova.<br />
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The study, published today in Nature Geoscience by researchers from UCL, Universidade de Lisboa, Universita di Padova, Kangwon National University and Tel Aviv University, provides evidence of dynamic movement in the Earth's lower mantle where ancient ocean floors are plunging towards the planet's core, crossing from the upper mantle (up to ~660 km below the crust) to the lower mantle (~660 -- 1,200 km deep).<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The team found that the deformation and increased flow in the lower mantle is likely due to the movement of defects in the crystal lattice of rocks in the deep Earth, a deformation mechanism called "dislocation creep," whose presence in the deep mantle has been the subject of debate.<br />
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The researchers used big data sets collected from seismic waves formed during earthquakes to probe what's happening deep in Earth's interior. The technique is well established and comparable to how radiation is used in CAT scans to see what's happening in the body.<br />
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"In a CAT scan, narrow beams of X-rays pass through the body to detectors opposite the source, building an image. Seismic waves pass through the Earth in much the same way and are detected by seismic stations on the opposite side of the planet to the earthquake epicentre, allowing us to build a picture of the structure of Earth's interior," explained Dr Sung-Joon Chang, Kangwon National University.<br />
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By combining 43 million seismic data measurements with dynamic computer simulations using the UK's supercomputing facilities HECToR, Archer and the Italian Galileo Computing Cluster, CINECA the researchers generated images to map how the Earth's mantle flows at depths of ~1,200 km beneath our feet.<br />
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They revealed increased mantle flow beneath the Western Pacific and South America where ancient ocean floors are plunging towards Earth's core over millions of years.<br />
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This approach of combining seismic data with geodynamic computer modelling can now be used to build detailed maps of how the whole mantle flows globally to see if dislocation creep is uniform at extreme depths.<br />
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The researchers also want to model how material moves up from the Earth's core to the surface, which together with this latest study, will help scientists better understand how our planet evolved into its present state.<br />
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"How mantle flows on Earth might control why there is life on our planet but not on other planets, such as Venus, which has a similar size and location in the solar system to Earth, but likely has a very different style of mantle flow. We can understand a lot about other planets from revealing the secrets of our own," concluded Dr Ferreira.</span><br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.ucl.ac.uk/news/2019/mar/earths-deep-mantle-flows-dynamically" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.ucl.ac.uk/" rel="nofollow" target="_blank">University College London</a>.</span></i></u></div>

Beneath Earth's Crust, Hot Rocks Creep as Oceanic Plates Plunge Toward the Core

Cross-sections of Earth’s mantle down to 1,400 km depth showing changes in its flow as ancient ocean beds fall into Earth’s deep interior...

'Mindblowing' Haul of Fossils Over 500M Years Old Unearthed in China

Earth History, evolution, Fossils 7:14 PM

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<tr><td class="tr-caption" style="text-align: center;">An undescribed species of Leanchoilia, an arthropod, from the Qingjiang fossil site.<br />
Photo: FU ET AL</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">Scientists have uncovered a wealth of well-preserved fossils in China from the early Cambrian Period, representing 101 species so far, over half of which have never been described before.</span><br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The most recent 12% of time on Earth is a striking anomaly when compared with the great bulk of our planet’s evolution. After 3 billion years or more of Earth as a microbial world, cells found ways to grow and assemble in their millions to build eyes, guts, muscles, nerve systems with brains, skeletons and the rest of the complex structures that form the mobile, sentient, marvellously various animals that fill our now familiar world.<br />
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The speed of this transition, seen by geologists in the sudden appearance of complex fossils such as trilobites in layers of rock, seemed so shockingly abrupt that it amazed and worried even Charles Darwin. As this flowering of complex multicellular life is used to mark the beginning of the Cambrian Period of Earth time, 541m years ago, it has long been called the “Cambrian explosion”.<br />
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We now know it was not quite so abrupt. The evolution actually took place in distinct stages over more than 30m years – the pioneering geologist Preston Cloud called it “the Cambrian eruption”.<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The period has, somewhat mysteriously, left behind more than its fair share of amazing fossil localities called “Lagerstätten”, where not only hard skeletons but soft and delicate tissues are preserved, to give a much clearer window on the totality of life than the usual fragments of shell and bone. The classic in this respect was long the Burgess Shale, high up on Mount Stephen in British Columbia, Canada, and mined for its wondrous fossils for more than a century. In the past three decades it has been joined by China’s Chengjiang deposits.<br />
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Together these have given a detailed picture from near the dawn of animal life in the marine realm (the land, then, was still largely barren): a wealth of arthropods, worms, lamp shells, sponges, chordates, and even some animals that still defy biological assignment.<br />
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Now another Cambrian Lagerstätte has turned up – and the first results, just published in Science, suggest that it may rival those of the Burgess Shale and Chengjiang. It is also in China, in Qingjiang in Hubei province, and is about the same age as the Chengjiang, some 518m years old, and so in the early part of the Cambrian Period. </span><br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">Indeed, it formed on the same general stretch of continental shelf sea as the Chengjiang fossils, about 1,000km away, and seemingly in somewhat deeper waters. What is surprising is that not only are the fossils just as exquisite, but they represent quite different animal communities. The Cambrian seas were clearly more diverse than thought, even in those early days.<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;"> Although the Qingjiang fossils do include many worms, arthropods and sponges, they also are prolific in animals possessing the most delicate and translucent of tissues, such as jellyfish, here preserved with mouths and tentacles, and their distant relatives “comb jellies”. </span><br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">These are rare in the Burgess Shale and Chengjiang deposits, but among the Qingjiang fossils there are many astounding examples, flattened on the shale surfaces and preserving fine details of these softest of anatomies.<br />
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The comb jellies may be the earliest form of animal – a title that they currently contest with the sponges. Both these kinds of animal are preserved here, in numbers and fidelity that may help resolve the dispute.<br />
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Other strange and wonderful animals appear in the Qingjiang strata, and represent curious and perhaps profound trends in evolution. There are kinorhynchs, for example – these are the “mud dragons”, animals that are today obscure because they are part of the “meiofauna”, those tiny creatures that live between grains of sediment on the sea floor.<br />
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Here, three new fossil forms have been found, some up to 4cm long, rather than the contemporary sub-millimetre size. These Cambrian giants suggest that some of today’s meiofauna started off “normally” sized, and then became miniaturised – for good.<br />
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It is a true cornucopia. How did it form? The same kind of quickfire preservation process is mooted as for the Burgess Shale and the Chengjiang fossils: the animals were caught up in mud slurries, and carried down to deep, oxygen-starved parts of the sea floor to be rapidly buried in the stifling mud. It makes sense – but then such conditions and processes persisted long after the Cambrian, and yet were rarely associated with such bonanza fossil finds. There is much that remains mysterious about the dawn of life as we know it – but the Qingjiang fossils, as we study them more, will slowly shed light on these enigmas.</span><br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The study was published in the journal <a href="http://science.sciencemag.org/content/363/6433/1338" rel="nofollow" target="_blank">Science</a>.</span></i></u><br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above post is reprinted from  <a href="https://theconversation.com/exquisite-fossil-finds-shed-new-light-on-the-cambrian-explosion-when-oceans-first-filled-with-complex-animal-life-114054" rel="nofollow" target="_blank">The Conversation.</a> </span></i></u></div>

'Mindblowing' Haul of Fossils Over 500M Years Old Unearthed in China

An undescribed species of Leanchoilia, an arthropod, from the Qingjiang fossil site. Photo: FU ET AL Scientists have uncovered a...

110-Million-year-old Bird Fossil Found With Egg Inside

evolution, Fossils 6:37 PM

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<tr><td class="tr-caption" style="text-align: center;">Photograph of the holotype of Avimaia schweitzerae.<br />
Photo Barbara Marrs</td></tr>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-family: "georgia" , "times new roman" , serif;">The 'first ever' bird fossil with an egg preserved inside the body has been discovered.</span></span></h4>
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</span> <span style="font-family: "arial" , "helvetica" , sans-serif;">A team of scientists led by Alida Bailleul and Jingmai O'Connor from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences reported the first fossil bird ever found with an egg preserved inside its body. Their findings were published on March 20 in Nature Communications.<br />
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The new specimen, representing a new species, Avimaia schweitzerae, was discovered in 110-million-year-old deposits in northwestern China. It belongs to a group called the Enantiornithes ("opposite birds"), which were abundant all around the world during the Cretaceous and co-existed with the dinosaurs.<br />
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The new fossil is incredibly well preserved, including the remains of an egg inside its abdomen. Because the specimen is crushed flat, it was only after a small fragment was extracted and analyzed under the microscope that the team realized that the unusual tissue was an egg.<br />
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Detailed analysis of the eggshell fragment revealed a number of interesting facts indicating the reproductive system of this female bird was not behaving normally: The egg shell consists of two layers instead of one as in normal healthy bird eggs, indicating the egg was retained too long inside the abdomen.<br />
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This condition often occurs in living birds as a result of stress. The unlaid egg then gets coated in a second layer (or sometimes more) of eggshell. This abnormality has also been documented in sauropod dinosaurs, as well as in many fossil and living turtles.<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">In addition, the eggshell preserved in Avimaia was extremely thin - thinner than a sheet of paper - and did not show the correct proportions of healthy eggs. (Note that avian eggshells consist of three sublayers with particular dimensions.)<br />
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These abnormalities suggest that the preserved egg may have been the cause of death of this "mother bird." Egg-binding, in which the egg becomes stuck inside the body causing death, is a serious and lethal condition that is fairly common in small birds undergoing stress.<br />
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Despite being malformed, the egg is excellently preserved, including parts of the eggshell that are rarely seen in the fossil record, such as traces of the egg membrane and the cuticle, which are mostly made of proteins and other organic materials.<br />
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Scanning electron microscopy revealed that the cuticle (the outer most protective layer of the eggshell) was made up of very small spherules of minerals. This type of cuticle morphology would be expected for birds that partially burry their eggs, as it has already been proposed to be the case for enantiornithines. Finding this morphology in Avimaia also supports the hypothesis that a cuticle with protective spherules represents the ancestral condition for avian eggs.<br />
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Female birds about to lay eggs deposit a unique bone tissue found inside the empty spaces of their skeleton, which serves as a calcium reservoir for the developing eggshell. Some researchers have argued that this tissue, called medullary bone, is present in other fossils (e.g., other fossil birds), as well as some non-avian dinosaurs and pterosaurs. However, some of these identifications were ambiguous.<br />
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Analysis of a fragment of leg bone from the new specimen revealed the presence of medullary bone. Avimaia is the only Mesozoic fossil in which additional morphological evidence of reproductive activity (i.e., the egg) supports the identification of medullary bone.<br />
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The preserved egg allows the specimen to be unequivocally identified as female, allowing scientists to test current hypotheses regarding sexual dimorphism (differences between genders).<br />
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This new specimen is arguably one of the most interesting Cretaceous fossil birds yet discovered, providing more reproductive information than any other Mesozoic fossil bird.</span><br />
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</span> <span style="font-family: "arial" , "helvetica" , sans-serif;"><i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.eurekalert.org/pub_releases/2019-03/caos-ncf031719.php" rel="nofollow" target="_blank">materials </a>provided by <a href="http://english.cas.cn/" rel="nofollow" target="_blank">Chinese Academy of Sciences Headquarters.</a></span></u></i></span></div>

110-Million-year-old Bird Fossil Found With Egg Inside

Photograph of the holotype of Avimaia schweitzerae. Photo Barbara Marrs The 'first ever' bird fossil with an egg preserved ...

Hundreds of Methane Vents Discovered Off Washington's Coast

Environment, Geology, Researches, USA 6:40 PM

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<tr><td class="tr-caption" style="text-align: center;">Red stars show locations of methane bubble plumes off Washington's coast. The light gray is the shallow continental shelf, less than 160 meters (175 yards) deep. The blue is the deeper margin and abyssal plain, deeper than 2.8 kilometers (1.7 miles). Credit: Paul Johnson/University of Washington</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">Off the coast of Washington, columns of bubbles rise from the seafloor, as if evidence of a sleeping dragon lying below. But these bubbles are methane that is squeezed out of sediment and rises up through the water. The locations where they emerge provide important clues to what will happen during a major offshore earthquake.</span><br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The study, from the University of Washington and Oregon State University, was recently published in the Journal of Geophysical Research: Solid Earth.<br />
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The first large-scale analysis of these gas emissions along Washington's coast finds more than 1,700 bubble plumes, primarily clustered in a north-south band about 30 miles (50 kilometers) from the coast. Analysis of the underlying geology suggests why the bubbles emerge here: The gas and fluid rise through faults generated by the motion of geologic plates that produce major offshore earthquakes in the Pacific Northwest.<br />
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"We found the first methane vents on the Washington margin in 2009, and we thought we were lucky to find them, but since then, the number has just grown exponentially," said lead author Paul Johnson, a UW professor of oceanography.<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">"These vents are a little ephemeral," Johnson added. "Sometimes they turn off-and-on with the tides, and they can move around a little bit on the seafloor. But they tend to occur in clusters within a radius of about three football fields. Sometimes you'll go out there and you'll see one active vent and you'll go back to the same location and it's gone. They're not reliable, like the geysers at Yellowstone."<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The authors analyzed data from multiple research cruises over the past decade that use modern sonar technology to map the seafloor and also create sonar images of gas bubbles within the overlying water. Their new results show more than 1,778 methane bubble plumes issuing from the waters off Washington state, grouped into 491 clusters.<br />
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"If you were able to walk on the seafloor from Vancouver Island to the Columbia River, you would never be out of sight of a bubble plume," Johnson said.<br />
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The sediments off the Washington coast are formed as the Juan de Fuca oceanic plate plunges under the North American continental plate, scraping material off the ocean crust. These sediments are then heated, deformed and compressed against the rigid North American plate. The compression forces out both fluid and methane gas, which emerges as bubble streams from the seafloor.<br />
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The bubble columns are located most frequently at the boundary between the flat continental shelf and the steeply sloped section where the seafloor drops to the abyssal depths of the open ocean. This abrupt change in slope is also a tectonic boundary between the oceanic and continental plates.<br />
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"Although there are some methane plumes from all depths on the margin, the vast majority of the newly observed methane plume sites are located at the seaward side of the continental shelf, at about 160 meters water depth," Johnson said.<br />
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A previous study from the UW had suggested that warming seawater might be releasing frozen methane in this region, but further analysis showed the methane bubbles off the Pacific Northwest coast arise from sites that have been present for hundreds of years, and are not related to global warming, Johnson said.<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Instead, these gas emissions are a long-lived natural feature, and their prevalence contributes to the continental shelf area being such productive fishing grounds. Methane from beneath the seafloor provides food for bacteria, which then produce large quantities of bacterial film. This biological material then feeds an entire ecological chain of life that enhances fish populations in those waters.<br />
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"If you look online at where the satellite transponders show where the fishing fleet is, you can see clusters of fishing boats around these methane plume hotspots," Johnson said.<br />
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To understand why the methane bubbles occur here, the authors used archive geologic surveys conducted by the oil and gas companies in the 1970s and 1980s. The surveys, now publicly accessible, show fault zones in the sediment where the gas and fluid migrate upward until emerging from the seafloor.<br />
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"Seismic surveys over the areas with methane emission indicate that the continental shelf edge gets thrust westward during a large megathrust, or magnitude-9, earthquake," Johnson said. "Faults at this tectonic boundary provide the permeable pathways for methane gas and warm fluid to escape from deep within the sediments."<br />
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The location of these faults could potentially provide new understanding of the earthquake hazard from the Cascadia Subduction Zone, which last ruptured more than 300 years ago. If the seafloor movement during a subduction-zone earthquake occurs closer to shore, and a major component of this motion occurs within the shallower water, this would generate a smaller tsunami than if the seafloor motion were entirely in deep water.<br />
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"If our hypothesis turns out to be true, then that has major implications for how this subduction zone works," Johnson said.</span><br />
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<br />
<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://www.washington.edu/news/2019/03/21/hundreds-of-bubble-streams-link-biology-seismology-off-washingtons-coast/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.washington.edu/" rel="nofollow" target="_blank">University of Washington</a>.</span></u></i></span></div>

Hundreds of Methane Vents Discovered Off Washington's Coast

Red stars show locations of methane bubble plumes off Washington's coast. The light gray is the shallow continental shelf, less than ...

520-Million-Year-Old Sea Monster Had 18 Mouth Tentacles

Earth History, Fossils 6:12 PM

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<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-BY1DRZOUfa8/XJZKAI-HgTI/AAAAAAAAQ3k/hQ8Exlnyzpc4mQ9b05HRUc8jX6o_bWefgCLcBGAs/s1600/518-million-year-old-daihua-fossil%2B%25281%2529.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="520-Million-Year-Old Sea Monster Had 18 Mouth Tentacles" border="0" data-original-height="824" data-original-width="1206" height="436" src="https://4.bp.blogspot.com/-BY1DRZOUfa8/XJZKAI-HgTI/AAAAAAAAQ3k/hQ8Exlnyzpc4mQ9b05HRUc8jX6o_bWefgCLcBGAs/s640/518-million-year-old-daihua-fossil%2B%25281%2529.jpeg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A detailed fossil of the newly identified Daihua sanqiong.<br />
Credit: Yang Zhao</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">One of the ocean's little known carnivores has been allocated a new place in the evolutionary tree of life after scientists discovered its unmistakable resemblance with other sea-floor dwelling creatures.</span><br />
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Comb jellies occupy a pivotal place in the history of animal evolution with some arguing that they were among the first animals to evolve. Now an international team of palaeontologists have found fossil evidence that proves comb jellies are related to ancestors that sat on the sea floor with polyp-like tentacles.<br />
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As reported today in Current Biology, researchers from the University of Bristol, Yunnan University in China and London's Natural History Museum, compared a 520 million-year-old fossil with fossils of a similar skeletal structure and found that all evolved from the same ancestors.<br />
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The fossil, set in a yellow and olive coloured mudstone and resembling a flower, was found in outcrops south of Kunming in the Yunnan Province, South China by Professor Hou Xianguang, co-author of the study.<br />
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Several amazingly preserved fossils have been unearthed from outcrops scattered among rice fields and farmlands in this part of tropical China in the last three decades.<br />
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It has been named Daihua after the Dai tribe in Yunnan and the Mandarin word for flower 'Hua', a cup-shaped organism with 18 tentacles surrounding its mouth. On the tentacles are fine feather-like branches with rows of large ciliary hairs preserved.<br />
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"When I first saw the fossil, I immediately noticed some features I had seen in comb jellies," said Dr Jakob Vinther, a molecular palaeobiologist from the University of Bristol. "You could see these repeated dark stains along each tentacle that resembles how comb jelly combs fossilise. The fossil also preserves rows of cilia, which can be seen because they are huge. Across the Tree of Life, such large ciliary structures are only found in comb jellies."<br />
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In today's oceans, comb jellies are swimming carnivores. Some of them have become invasive pests. They swim using bands of iridescent, rainbow coloured comb rows along their body composed of densely packed cellular protrusions, known as cilia. Their hair-like structures are the largest seen anywhere in the tree of life.<br />
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The researchers noticed that Daihua resembled another fossil, a famous weird wonder from the Burgess Shale (508 million years old) called Dinomischus. This stalked creature also had 18 tentacles and an organic skeleton and was previously assigned to a group called entoprocts.<br />
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"We also realised that a fossil, Xianguangia, that we always thought was a sea anemone is actually part of the comb jelly branch," said co-author Prof Cong Peiyun.<br />
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This emerging pattern led researchers to see a perfect transition from their fossils all the way up to comb jellies.<br />
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"It was probably one of the most exhilarating moments of my life," said Dr Vinther. "We pulled out a zoology textbook and tried to wrap our head around the various differences and similarities, and then, bam! -- here is another fossil that fills this gap."<br />
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The study shows how comb jellies evolved from ancestors with an organic skeleton, which some still possessed and swam with during the Cambrian. Their combs evolved from tentacles in polyp-like ancestors that were attached to the seafloor. Their mouths then expanded into balloon-like spheres while their original body reduced in size so that the tentacles that used to surround the mouth now emerges from the back-end of the animal.<br />
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"With such body transformations, I think we have some of the answers to understand why comb jellies are so hard to figure out. It explains why they have lost so many genes and possess a morphology that we see in other animals," added co-author Dr Luke Parry.<br />
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Until around 150 years ago, zoologists had considered comb jellies and cnidarians to be related. This theory was challenged more recently by new genetic information suggesting comb jellies could be a distant relative to all living animals below the very simple looking sponges.<br />
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The authors of this new study believe their findings make a strong case for repositioning the comb jelly back alongside corals, sea anemones and jellyfish.<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://www.bristol.ac.uk/news/2019/march/comb-jellies.html" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.bristol.ac.uk/" rel="nofollow" target="_blank">University of Bristol</a>.</span></i></u></div>

520-Million-Year-Old Sea Monster Had 18 Mouth Tentacles

A detailed fossil of the newly identified Daihua sanqiong. Credit: Yang Zhao One of the ocean's little known carnivores has been ...

Meteor Blast Over Bering Sea Was 10 Times Size of Hiroshima

Meteorite, News 6:58 PM

Meteor Blast Over Bering Sea Was 10 Times Size of Hiroshima

A dashcam image of the Chelyabinsk meteor. The meteor last December exploded over a more remote location. Photograph: AP A meteor ...

Researchers Unravel Mysteries of Earth's Inner Core

earth, Tectonic 7:26 PM

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Researchers from The Australian National University (ANU) are unlocking some of the secrets of the Earth's inner core by adapting and further developing a technique used in hospitals around the world.<br />
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Tomography is the imaging process used in x-rays and ultrasounds, and involves waves passing through the body, before bouncing off body tissue and back to a receiver.<br />
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ANU researcher Professor Hrvoje Tkalčić said it's also turned out to be a useful way for seismologists to "see" inside the Earth—with a couple of key differences.<br />
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"This is one of the first attempts at tomography of the Earth's inner core."<br />
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"In medicine they have an infinite number of sources and receivers they can place around the body, depending on the problem area. Earth scientists have to rely on natural sources—or earthquakes—and seismometers, and we don't have full control over their location."<br />
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"One of the key things we can measure is the travel time of waves through the planet, from the time a large earthquake happens to when it gets recorded by the instrument on the other side of the globe."<br />
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This travel time, and how much the waves attenuate—or lose energy—can provide crucial information about the material they're passing through, in the same way x-rays can pick up abnormal structures in the human body.<br />
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The ANU team used a ground breaking method to improve the accuracy of their results, employing a complex computer algorithm.<br />
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"We used what's called a "trans-dimensional" algorithm. This means the dimension of our problem is changing as we are solving it, or in other words the number of unknowns in our problem is itself an unknown," Dr. Tanja Pejić said.<br />
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"This is a highly computationally complex problem, with individual computations taking weeks to solve on the RSES's Terrawulf computer cluster. The answer is a whole ensemble of solutions, and averaging through it gives us a statistically more likely solution."<br />
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The study focused on imaging the top layer of the Earth's inner core, an area seen by some scientists as a 'final frontier' of global seismology.<br />
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"For the past few decades scientists have been locked in a debate about the inner core's formation, dynamics, and growth," Dr. Pejić said.<br />
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"Our paper shows that the eastern hemisphere is highly attenuative for seismic waves, but also that the western hemisphere—instead of being less attenuative—can be further divided into two regions. One region is potentially even more attenuative than all of the eastern hemisphere, and the other region is less attenuative."<br />
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Professor Tkalčić said these findings could provide new evidence about the connection between the inner core and other parts of the earth.<br />
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"We can learn from these tomographic images something about the dynamics of the entire system, the entire core and its connection to the lower mantle and the surface of the Earth."<br />
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"Even though this is a snapshot of the current view of the Earth, it could help us better understand the formation process of the solid inner core, and even planetary formation in general."<br />
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"We are slowly getting there."<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://science.anu.edu.au/research/research-stories/anu-researchers-unravel-mysteries-earths-inner-core" rel="nofollow" target="_blank">materials </a>provided by <a href="http://www.anu.edu.au/" rel="nofollow" target="_blank">The Australian National University.</a></span></i></u></div>

Researchers Unravel Mysteries of Earth's Inner Core

Researchers from The Australian National University (ANU) are unlocking some of the secrets of the Earth's inner core by adapting a...

Yellowstone’s Geysers Are Getting More Active. Nobody’s Sure Why

Tectonic, USA, Yellowstone 5:53 PM

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<tr><td class="tr-caption" style="text-align: center;">Steamboat Geyser experiences a relatively minor eruption in a picture taken in Yellowstone National Park. Recently, the geyser set a record by erupting 32 times in a single year.<br /></td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">The geysers in Yellowstone National Park are as breathtakingly beautiful as they are mercurial. Old Faithful is famous in part because of its predictability, since most of these natural fonts are much more inscrutable.</span><br />
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Something odd is going on in Yellowstone National Park. Geysers that would once erupt every half century are now spouting steam every week.<br />
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And, late last year, one slumbering geyser — dubbed Ear Spring — vomited up 80 years worth of trash. The spring’s last big blow was in 1957. So, when it blew to a height of some 9m in September, National Parks officers spent days collecting old coins, beer cans, and even a 1930s baby dummy from its surrounds.<br />
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“An approximately 8-foot diameter area of surrounding ground is ‘breathing’ — rising and falling by about six inches every 10 minutes,” USGS researchers said.<br />
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While the eruption offered up an interesting time capsule, it’s also represents of what researchers are calling an unusual upturn in geyser activity.<br />
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The Steamboat geyser used to erupt erratically, sometimes after a duration as short as four days or as long as 50 years. Lately, it’s been sending spouts of steaming water 90m high into the air once every week.<br />
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The Yellowstone Volcano Observatory says it erupted 32 times last year.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">What’s Going on?</span></h4>
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However, USGS and park officials have stressed in recent months that there have been no signs of volcanic activity.<br />
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“Changes in Yellowstone’s hydrothermal features are common occurrences and do not reflect changes in activity of the Yellowstone volcano,” they said in a statement.<br />
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This is because the hydrothermal system — where water pools among the cracks in the rocks of the earth’s surface — is limited to mainly just the top 30m or so.<br />
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The magma that triggers volcanic activity resides several kilometres deeper.<br />
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“There has been no significant increase in seismicity nor broadscale variations in ground movement,” the USGS says.<br />
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And the geysers’ behaviour remains erratic.<br />
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“It’s a good lesson in how geysers actually work,” Michael Poland, the scientist-in-charge at Yellowstone Volcano Observatory, told National Geographic . “As soon as you start to recognise a pattern, it changes.”</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Apocalypse? Nope.</span></h4>
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With all this in mind, do we know what’s going on at Yellowstone? There’s been no change in the underlying heat source, and no major geological changes, Poland says.<br />
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However, the last few years have been exceptionally snowy, so a change in the supply of subsurface water may be a major factor. As it happens, the second-longest earthquake swarm in the park’s recorded history took place in 2017. Research tentatively suggests that the same heavy precipitation may have provided the faults involved with plenty of lubrication, allowing them to jut forward with reckless abandon.<br />
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In both cases, it’s difficult to make any definitive statements. There aren’t really any direct measurements of the subsurface water in the park, and such inferences are based on the records of surface water and precipitation. For now, Poland says, “we’re just speculating.”<br />
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What absolutely isn’t worth speculating about is the state of Yellowstone’s infamous volcanic system. Any uptick in any sort of activity at Yellowstone seems to spark fears about a catastrophic eruption of the park’s huge caldera, even though such worries are unfounded.<br />
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There has been no change to the underlying magma reservoir over the past few years, Poland emphasizes. Plus, the mischief of any of the park’s geysers—which operate at the very top of the crust—has no bearing whatsoever on that mostly solid magma cache many miles below the surface.</div>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Further reading:</span></b></div>
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<a href="https://www.nationalgeographic.com/science/2019/02/some-yellowstone-geysers-getting-more-active-but-why-geology/" rel="nofollow" target="_blank">National Geographic</a></div>
<div style="text-align: left;">
<a href="https://www.news.com.au/technology/environment/natural-wonders/yellowstones-geysers-are-getting-more-active-nobodys-sure-why/news-story/d90fcb153eb7d2260da14b02239bb773" rel="nofollow" target="_blank"> News.com.au</a></div>
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