Impact of tsunami on the Columbia River

February 19, 2015

Tsunami impact map. Credit: Image courtesy of Oregon State University

Engineers at Oregon State University have completed one of the most precise evaluations yet done about the impact of a major tsunami event on the Columbia River, what forces are most important in controlling water flow and what areas might be inundated.
They found, in general, that tidal stages are far more important than river flow in determining the impact of a tsunami; that it would have its greatest effect at the highest tides of the year; and that a tsunami would be largely dissipated within about 50 miles of the river’s mouth, near Longview, Wash.

Any water level increases caused by a tsunami would be so slight as to be almost immeasurable around the Portland metropolitan area or Bonneville Dam, the study showed. But water could rise as much as 13 feet just inside the mouth of the Columbia River, and almost 7 feet within a few miles of Astoria.

“There have been previous models of Columbia River run-up as a result of a tsunami, but they had less resolution than this work,” said David Hill, an associate professor of civil engineering in the OSU College of Engineering. “We carefully considered the complex hydrodynamics, subsidence of grounds that a tsunami might cause, and the impacts during different scenarios.”

The impact of tsunamis on rivers is difficult to predict, researchers say, because many variables are involved that can either dampen or magnify their effect. Such factors can include the width and shape of river mouths, bays, river flow, tidal effects, and other forces.

But the major tsunami in Japan in 2011, which was caused by geologic forces similar to those facing the Pacific Northwest, also included significant inland reach and damage on local rivers. As a result, researchers are paying increased attention to the risks facing residents along such rivers.

The OSU research has been published in the Journal of Waterway, Port, Coastal and Ocean Engineering, by Hill and OSU graduate student Kirk Kalmbacher. It’s based on a major earthquake on the Cascadia Subduction Zone and a resulting tsunami, with simulations done at different rivers flows; and high, low, flood and ebb tides.

Of some interest is that the lowest elevation of a tsunami wave generally occurs at a high tide, but its overall flooding impact is the greatest because the tide levels are already so high. Because of complex hydrodynamic interactions, the study also found that only on a flood tide would water actually wash up and over the southern spit of the Columbia River mouth, with some local flooding based on that.

Tides, overall, had much more impact on the reach of a tsunami than did the amount of water flowing in the river.

“We were a little surprised that the river’s water flow didn’t really matter that much,” Hill said. “The maximum reach of a tsunami on the Columbia will be based on the tidal level at the time, and of course the magnitude of the earthquake causing the event.”

Based on a maximum 9.0 magnitude earthquake and associated tsunami, at the highest tide of the year, the research concluded:

Just offshore, the tsunami would raise water levels about 11.5 to 13 feet.
Just inside the mouth of the Columbia River, the water would rise about 13 feet.
At river mile 6, approaching Hammond, Ore., the river would rise about 10 feet.
At river mile 25, near Welch Island, the river would rise about 1.6 feet.
At river mile 50, near Longview, Wash., there would be no measurable rise in the river.

Maps have been developed as a result of this research that make more precise estimates of the areas which might face tsunami-induced flooding. They should aid land owners and land use planners, Hill said, in making improved preparations for an event that researchers now say is inevitable in the region’s future. Experts believe this region faces subduction zone earthquakes every 300-600 years, and the last one occurred in January, 1700.

There are some noted differences in the projections on these newer maps and older ones, Hill said.

Note: The above story is based on materials provided by Oregon State University.

Animals tend to evolve toward larger size over time, Stanford study finds

February 19, 2015

Prof. Jonathan Payne (right) and Noel Heim, a postdoctoral researcher in Payne’s lab, stand next to stacks of the Treatise on Invertebrate Paleontology, which they recently used to provide fresh evidence of Cope’s rule. Credit: Courtesy of Noel Heim

Does evolution follow certain rules? If, in the words of the famed evolutionary biologist Stephen Jay Gould, one could “rewind the tape of life,” would certain biological trends reemerge? Asked another way: can evolution be predicted?

New research suggests that, for at least one important biological trait-body size-the answer is yes.
In one of the most comprehensive studies of body size evolution ever conducted, Stanford scientists have found fresh support for Cope’s rule, a theory in biology that states that animal lineages tend to evolve toward larger sizes over time.

“We’ve known for some time now that the largest organisms alive today are larger than the largest organisms that were alive when life originated or even when animals first evolved,” said Jonathan Payne, a paleobiologist at Stanford’s School of Earth, Energy & Environmental Sciences.

What was unclear, however, was whether the average size of animals has been changing over time and, if so, whether that reflects a trend, or directionality, in body size evolution. “It’s not something that you can know by just studying living organisms or extrapolating from what you see over short time scales. If you do that, you will absolutely be wrong about the rate, and possibly also the direction,” Payne said.

The study, published in the Feb. 20 issue of the journal Science, reveals that over the past 542 million years, the mean sized of marine animals has increased 150-fold. “That’s the size difference between a sea urchin that is about 2 inches long versus one that is nearly a foot long,” Heim said. “This may not seem like a lot, but it represents a big jump.”

The research also found that the increase in body size that has occurred since animals first appeared in the fossil record around 550 million years ago is not due to all animal lineages steadily growing bigger, but rather to the diversification of groups of organisms that were already larger than other groups early in the history of animal evolution.

“That’s also something we didn’t know before,” Payne said. “For reasons that we don’t completely understand, the classes with large body size appear to be the ones that over time have become differentially more diverse.”

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A universal trend?

Named after paleontologist Edward Cope, Cope’s rule was formulated in the late 19th century after paleontologists noticed that the body sizes of terrestrial mammals such as horses generally increased over time.

Scientists have attempted to test Cope’s rule in other animal groups, but the conclusions have been mixed. Corals and dinosaurs seem to follow Cope’s rule, for example, but birds and insects do not. As a result, some scientists have wondered whether the pattern observed in land mammals is a real evolutionary phenomenon or merely a statistical one resulting from random, non-selective evolution, also known as neutral drift. “It’s possible that as evolution proceeds, there really is no preference for being larger or smaller,” said Noel Heim, a postdoctoral researcher in Payne’s lab. “What appears to be an increase in average body size may be due to neutral drift.”

To test whether Cope’s rule applies to marine animals as a whole, Payne and a team that included undergraduates and high school interns compiled a dataset including more than 17,000 groups, or genera, of marine animals spanning five major phyla-Arthropods, Brachiopods, Chordates, Echinoderms, and Mollusks-and the past 542 million years. “Our study is the most comprehensive test of Cope’s rule ever conducted,” Heim said. “Nearly 75 percent of all of marine genera in the fossil record and nearly 60 percent of all the animal genera that ever lived are included in our dataset.”

To compile such a vast dataset, the team relied heavily on the Treatise on Invertebrate Paleontology, a 50-volume book set that includes detailed information about every invertebrate animal genus with a fossil record known to science. Using photographs and detailed illustrations of fossils in the Treatise, the team was able to calculate and analyze body size and volume for 17,208 marine genera.

A pattern soon became apparent: not all classes-groups of related species and genera-of animals trended toward larger size, but those that were bigger tended to become more diverse over time. The team suspects this is due to advantages associated with a larger size, such as the ability to move faster, burrow more deeply and efficiently in sediment, or capture larger prey.

“It’s really a story of the survival and diversification of big things relative to small things,” Heim said.

Virtual evolution

To investigate what might drive these trends toward larger body sizes, the team entered their measurement data into a computer model designed to simulate body size evolution. Beginning with the smaller species from each phylum, the model simulated how their body sizes might change as they evolved into new species. “As time marches forward, each species is assigned some probability of producing a new species, of remaining the same, or of going extinct, at which point it drops out of the race,” Heim said.

When a new virtual species was created, the model assigned the new creature a body size that could be bigger or smaller than its ancestor. The scientists ran multiple simulations, each with different assumptions. One scenario, for instance, assumed a neutral drift model of evolution, in which body size fluctuates randomly without affecting the survival of the species. Another assumed natural selection, or “active evolution,” of body size, in which having a larger body size confers certain survival advantages and is thus more likely to propagate through the generations.

The team found that the neutral drift simulation could not explain the body size trends observed in the fossil record. “The degree of increase in both mean and maximum body size just aren’t well explained by neutral drift,” Heim said. “It appears that you actually need some active evolutionary process that promotes larger sizes.”

The team believes that the vast database they compiled will be useful for studying other questions related to body size, such as whether or not organisms near the equator are, on average, bigger or smaller than those living at higher latitudes.

The findings could also prompt other scientists to investigate whether there is a trend in the evolution of other traits. “The discovery that body size often does evolve in a directional way makes it at least worth asking whether we’re going to find directionality in other traits if we measure them carefully and systematically,” Payne said.

Reference:
Noel A. Heim, Matthew L. Knope,†, Ellen K. Schaal,‡, Steve C. Wang, Jonathan L. Payne. Cope’s rule in the evolution of marine animals. Science, 2015 DOI: 10.1126/science.1260065

Note: The above story is based on materials provided by Stanford School of Engineering.

Does dark matter cause mass extinctions and geologic upheavals?

February 19, 2015

NGC 4565, an edge-on spiral galaxy. The stars, dust and gas are concentrated into a thin disc, much like the one in our Milky Way galaxy. Credit: Jschulman555

Research by New York University Biology Professor Michael Rampino concludes that Earth’s infrequent but predictable path around and through our Galaxy’s disc may have a direct and significant effect on geological and biological phenomena occurring on Earth. In a new paper in Monthly Notices of the Royal Astronomical Society, he concludes that movement through dark matter may perturb the orbits of comets and lead to additional heating in Earth’s core, both of which could be connected with mass extinction events.
The Galactic disc is the region of the Milky Way Galaxy where our solar system resides. It is crowded with stars and clouds of gas and dust, and also a concentration of elusive dark matter — small subatomic particles that can be detected only by their gravitational effects.

Previous studies have shown that Earth rotates around the disc-shaped Galaxy once every 250 million years. But Earth’s path around the Galaxy is wavy, with the Sun and planets weaving through the crowded disc approximately every 30 million years. Analyzing the pattern of Earth’s passes through the Galactic disc, Rampino notes that these disc passages seem to correlate with times of comet impacts and mass extinctions of life. The famous comet strike 66 million ago that led to the extinction of the dinosaurs is just one example.

What causes this correlation between Earth’s passes through the Galactic disc, and the impacts and extinctions that seem to follow?

While traveling through the disc, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from Earth in the outer Solar System, Rampino observes. This means that comets that would normally travel at great distances from Earth instead take unusual paths, causing some of them to collide with the planet.

But even more remarkably, with each dip through the disc, the dark matter can apparently accumulate within Earth’s core. Eventually, the dark matter particles annihilate each other, producing considerable heat. The heat created by the annihilation of dark matter in Earth’s core could trigger events such as volcanic eruptions, mountain building, magnetic field reversals, and changes in sea level, which also show peaks every 30 million years. Rampino therefore suggests that astrophysical phenomena derived from Earth’s winding path through the Galactic disc, and the consequent accumulation of dark matter in the planet’s interior, can result in dramatic changes in Earth’s geological and biological activity.

His model of dark matter interactions with Earth as it cycles through the Galaxy could have a broad impact on our understanding of the geological and biological development of Earth, as well as other planets within the Galaxy.

Rampino said: “We are fortunate enough to live on a planet that is ideal for the development of complex life. But the history of Earth is punctuated by large scale extinction events, some of which we struggle to explain. It may be that dark matter — the nature of which is still unclear but which makes up around a quarter of the universe — holds the answer. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth.”

In the future, he suggests, geologists might incorporate these astrophysical findings in order to better understand events that are now thought to result purely from causes inherent to Earth. This model, Rampino adds, likewise provides new knowledge of the possible distribution and behavior of dark matter within the Galaxy.

Reference:
Michael R. Rampino. Disc dark matter in the Galaxy and potential cycles of extraterrestrial impacts, mass extinctions and geological events. Monthly Notices of the Royal Astronomical Society, 2015 DOI: 10.1093/mnras/stu2708

Note : The above story is based on materials provided by Royal Astronomical Society (RAS).

Secret of extinct British marine reptile uncovered

February 19, 2015

A new type of ichthyosaur, an extinct marine reptile which was alive at the same time as the dinosaurs, has been identified from a fossil found on Dorset’s Jurassic coast.

The fossil had been in the collections of Doncaster Museum and Art Gallery for more than 30 years until Dean Lomax (25) palaeontologist and Honorary Scientist at The University of Manchester, uncovered its hidden secrets.

Dean first examined the fossil in 2008 when he noticed several abnormalities in the bone structure which made him think he had something previously unidentified. Working with Professor Judy Massare of Brockport College, New York, he spent over five years travelling the world to check his findings and a paper explaining the discovery is published today in the Journal of Vertebrate Paleontology.

Dean said: “After examining the specimen extensively, both Professor Massare and I identified several unusual features of the limb bones (humerus and femur) that were completely different to any other ichthyosaur known. That became very exciting. After examining perhaps over a thousand specimens we found four others with the same features as the Doncaster fossil.”

Similar-shaped to dolphins and sharks, ichthyosaurs, which are often misidentified as ‘swimming dinosaurs’, swam the seas of the earth for millions of years during the Triassic, Jurassic and Cretaceous periods, before being wiped out. The Doncaster fossil is between 189 and 182 million years old, from a time in the early Jurassic period called the Pliensbachian. It is the world’s most complete ichthyosaur of this age.

“The recognition of this new species is very important for our understanding of ichthyosaur species diversity during the early Jurassic, especially from this time interval, ” Dean added.

The research also looked at the size and age of the new species, and enabled a look at sexual differences (males and females). This included comparison with other groups of reptiles (living and extinct), whose limb bones are different between males and females, something that had never before been applied to ichthyosaurs. The limb bones of the Doncaster specimen were professionally prepared and removed, funded by the Esmée Fairbairn Foundation, as part of a grant awarded to Doncaster Museum Service.

The new species has been named Ichthyosaurus anningae in honour of the British collector, and woman in science, Mary Anning, who first collected ichthyosaurs in the early 1800’s. It is the first new Ichthyosaurus identified for almost 130 years.

Dean added: “Mary worked tirelessly to bring the ichthyosaurs, among other fossils, to the attention of the scientific world. Mary and her brother, Joseph, discovered the first ichthyosaur specimen to be scientifically recognised, collected at Lyme Regis around 1811.”

“It is an honour to name a new species, but to name it after somebody who is intertwined with such an important role in helping to sculpt the science of palaeontology, especially in Britain, is something that I’m very proud of. In fact, one of the specimens in our study was even found by Mary herself! Science is awesome.”

“This discovery shows that new species, and not only ichthyosaurs, are awaiting discovery in museum collections. Not all new discoveries are made in the field.”

Note : The above story is based on materials provided by University of Manchester.

Rust preserves fossils from early Earth

February 19, 2015

Since life originated on Earth between 3.8 and 3.9 Ga ago, microorganisms have significantly shaped and influenced the chemistry of Earth’s surface and subsurface environments. Reconstructing the evolution of early microbial life depends mainly on finding organic and mineral remnants of microbial activity preserved in the rock record.

Even when microfossils are found, there are often controversies about their biological origin, since parameters that lead to a good preservation of microfossils are not well constrained. In a study published in Nature Communications, researchers from the University of Tübingen, Dr. Aude Picard (now at Harvard University in Cambridge, MA), Dr. Martin Obst, Professor Andreas Kappler, and Gregor Schmid, in collaboration with Dr. Luca Quaroni from the Paul Scherrer Institute in Villigen, Switzerland, show that microbial structures that are embedded in iron minerals are preserved under pressure and temperature conditions that occur during rock formation.

Some microaerophilic Fe(II)-oxidizing bacteria produce organo-mineral structures, so-called twisted stalks, in the presence of high iron and low oxygen concentrations. Nowadays such environments are limited to a few places on Earth, such as caves, mines, deep-sea hydrothermal vents and some lake and marine sediments. But in the past, when the oceans were rich in iron and oxygen started to accumulate in the atmosphere, these microorganisms would have thrived. If found in rocks having experienced a diagenetic history, these structures could help identify the presence of low oxygen concentrations in ancient iron-rich environments.

For this study, Dr. Aude Picard and colleagues Dr. Martin Obst and Gregor Schmid went sampling microbial mats in the historical Segen Gottes silver mine (Black Forest, SW Germany) that contained twisted stalks and submitted them to pressure and temperature conditions that are typically encountered during rock formation, e.g. up to 250°C and 140 MPa. Twisted stalks were then observed using microscopic and spectroscopic techniques, 1) to determine whether structures are preserved and 2) to characterize their mineral and organic composition and 3) to provide spectroscopic signatures that could be useful for microfossil search in the rock record.

Using confocal laser microscopy and electron microscopy, coupled with the use of advanced synchrotron techniques at the Swiss Light Source, in Villigen (Switzerland), and at the Canadian Light Source in Saskatoon, Canada, the team was able to show that not only the morphology of microbial twisted structures is preserved after long incubations under diagenetic conditions, but also organic remnants can be detected in the mineralized twisted structures. During this study they demonstrated the important role that iron plays in the preservation of these structures submitted to extreme conditions. They finally provide experimental signatures that could be of use when studying rock samples. These new findings will help to better identify microfossils in the rock record, especially at a critical time on Earth when oxygen started to be an important component of the atmosphere.

Refernce:
Picard A., Kappler A., Schmid G., Quaroni L., Obst M. (2015) Experimental diagenesis of organo-mineral structures formed by microaerophilic Fe(II)-oxidizing bacteria. Nature Communications, DOI: 10.1038/ncomms7277.

Note : The above story is based on materials provided by University of Tübingen.

Solving carbon mysteries of the deep ocean

February 19, 2015

Based on mathematical modeling of dissolved organic carbon, researchers are beginning to see the outlines of a new deep sea carbon cycle — one in which dissolved carbon is continually added and removed by a number of diverse processes. Credit: Dan Repeta/WHOI

Understanding how oceans absorb and cycle carbon is crucial to understanding its role in climate change. For approximately 50 years, scientists have known there exists a large pool of dissolved carbon in the deep ocean, but they didn’t know much about it—such as the carbon’s age (how long it’s been in organic form), where it came from, how it got there, and how long it’s been there, or how these factors influence its role in the carbon cycle.
Now, new research from scientists at MIT and Woods Hole Oceanographic Institute (WHOI) provides deeper insights into this reservoir and reveals a dynamic deep-ocean carbon cycle mediated by the microbes that call this dark, cold environment home. The work, published in Proceedings of the National Academy of Sciences, suggests the deep ocean plays a significant role in the global carbon cycle, and has implications for our understanding of climate change, microbial ecology, and carbon sequestration.

For years, scientists thought that carbon of varying ages made up the deep-ocean reservoir and fueled the carbon cycle, but nobody could prove it. “I’ve been trying for over 20 years,” said Daniel Repeta, a senior scientist in marine chemistry and geochemistry at WHOI and co-author of the study. “Back then we didn’t have a good way to go in and pull that carbon apart to see the pieces individually. We would get half-answers that suggested this was happening, but the answer wasn’t clear enough,” he says. With the help of Daniel Rothman, a professor of geophysics in MIT’s Department of Earth, Atmospheric, and Planetary Sciences (EAPS), and Chris Follett, a postdoctoral associate in Mick Follows’ group and formerly of Rothman’s group, Repeta would soon find the answers he was looking for.

Follett thought a next-generation method called a step-wise oxidation test might be able to reveal the age distribution of the carbon pool. The team exposed water samples taken from the Pacific Ocean to ultraviolet radiation, which converts organic carbon to carbon dioxide. The gas was then collected and measured for radiocarbon, which Follett used to estimate the carbon isotopes’ ages and cycling rate. “At a minimum there are two widely separated components—one extremely young and one extremely old, and this young component is fueling the larger flux through the dissolved carbon pool,” he says.

In other words, the youngest source of dissolved organic carbon in the deep ocean originates from the surface, where phytoplankton and other marine life fix carbon from the atmosphere. Eventually these organisms die and sink down the water column, where they dissolve and are consumed by microbes. Because it takes 1,000 years for the ocean’s surface waters to replace bottom waters, scientists thought the few-centuries-old carbon, some of which is anthropogenic, couldn’t possibly contribute to the deep ocean pool. That’s no longer the case.

The researchers found that as particulate organic carbon sinks through the water column and dissolves, some of it is sequestered in the reservoir and respired by microbes. The results suggest a more active carbon cycle in the deep ocean bolstered by bacteria that utilize the reservoir as a food source. “We previously thought of the deep ocean as a lifeless and very slow system,” Repeta says. “But those processes are happening much faster than we thought.” If this microbial pump is in fact more robust, then it gives more credence to the idea of using the mechanism to sequester carbon in the deep ocean—a concept some scientists have been working on in recent years.

While some carbon in the reservoir may cycle faster, older carbon cycles much slower. This is because older sources such as hydrothermal vents, methane seeps, and ocean sediment produce carbon that isn’t easily consumed. However, these sources are often disregarded in analyses of the marine carbon cycle because they are considered too small in magnitude to be significant. But when Follett accounted for them in calculating the reservoir’s turnover, or the time it takes for carbon to completely cycle, what he found was astounding. The turnover time of the older portion of the reservoir is 30,000 years—30 times longer than it takes for the ocean itself to cycle—which indicates these sources may be relevant. “To find something that is more consistent with the biochemical story was fun and surprising,” says Follett. “A lot of people have proposed these ideas over the years, but they haven’t had the evidence to back them up. It was nice to come in and give them the evidence they needed to support these ideas.”

So what do these findings mean for the climate system? In the short term, not much. But on a longer time-scale, one that spans thousands of years, it could affect projections of the amount of atmospheric and sequestered carbon. “It potentially has a very important influence on climate through its role in sequestration of carbon away from the atmosphere,” says Mick Follows, an EAPS associate professor in the Program of Atmospheres, Oceans, and Climate, who was not involved in the study. “If some radical change occurred that changed the nature of that pool, then it could have an effect on climate through greenhouse gas’ influence on the atmosphere.” Such changes might include, for example, deep-ocean temperature fluctuations affecting microbial activity, or a shifting surface ocean environment that could affect plankton and other organisms from which dissolved organic carbon originates.

“One of the things I’ve taken away from the work is that in a way, they’ve transformed a view of how people are thinking that pool is turning over in the deep ocean and what the sources of that are,” says Follows. “It seems like a very profound change in our understanding of how the system works relative to ingrained perspectives.”

Reference:
“Hidden cycle of dissolved organic carbon in the deep ocean.” PNAS 2014 111 (47) 16706-16711; published ahead of print November 10, 2014, DOI: 10.1073/pnas.1407445111

Note : The above story is based on materials provided by Massachusetts Institute of Technology.

Rare Antarctic sub-glacial eruption

February 19, 2015

Frozen Spring. Credit: Ali Dean/Australian Antarctic Division

Australian scientists are hoping a rare sub-glacial water eruption near Australia’s Casey station, will reveal why meltwater is present, and the extent of a river and dam system flowing deep under the Law Dome ice cap.
In only the second reported incident of its type in Antarctica a Jökulhlaup, or sudden outburst of basal melt water from beneath the ice cap, erupted near Robinsons Ridge, 15 kilometres south of Casey.

Associate Professor Ian Goodwin from Macquarie University observed the first recorded Antarctic Jökulhlaup, also near Casey station, in 1985-86, and located a large subglacial lake near the ice margin.

The new eruption was first noticed by Casey expeditioners over the 2014 winter, who were puzzled by springs of flowing water erupting from the surface of the ice.

“The expeditioners saw the melt water rising to the surface and dispersing over the surrounding ice sheet, before refreezing,” Professor Goodwin said.

“The refrozen Jökulhlaup water is very prominent because of its striking olive-green colour, which contrasts sharply with the surrounding blue glacial ice and white snow.

“This is a very exciting and rare opportunity to find out more about the conditions under Law Dome from this sub-glacial water which is potentially tens of thousands of years old.”

Samples of the frozen Jökalhlaup water are currently being collected by scientists from the CSIRO and the Australian Nuclear Science and Technology Organisation.

The ice will then be analysed in new ice laboratory facilities at Macquarie University, Curtin University and the Antarctic Climate and Ecosystems CRC.

“There have been advances in technology and techniques since the last known eruption 30 years ago, which will allow us to measure the hydro chemistry in much more detail from these samples,” Professor Goodwin said.

“We will measure the major ionic chemistry and isotopes to find out how the bottom of the ice sheet is melted, how far the water has travelled, and an insight into the stability of the ice sheet.

“We are also attempting to estimate the age of the water,” he said.

“Additionally, if the researchers can get a sample close to the water when it’s erupting, they will take refrozen samples to measure the methane and greenhouse gas content in the sub glacial meltwater.”

Program leader with the Australian Antarctic Division, Dr Tas van Ommen, said previous aerial radar work through the ICECAP project will help the researchers pinpoint the origin of the water.

“The ICECAP work used ice-penetrating radar to map the conditions at the base of the ice sheet in East Antarctica, and this can help identify which areas are more likely to produce basal melting and water,” Dr van Ommen said.

“Putting the whole picture together, with data from ICECAP, deep ice core temperature measurements on Law Dome and samples from the Jökalhlaup, will help us understand the past and present behaviour of the ice cap, and how it might evolve in the future,” he said.

Previously, scientists thought the Law Dome ice cap was frozen to the bedrock. However, the outburst of the frozen spring in 1985 showed water is produced underneath some parts of the ice cap, at least episodically.

“Our observations of the Jökulhlaup confirmed Law Dome had high geo-thermal heat emanating from the Earth’s crust which was melting the bottom of the ice cap,” Professor Goodwin said.

“This water then flowed in river systems under the ice sheet out into the ocean, or in this case, where the rivers are dammed by frozen ice, the water flows up to the surface through weaknesses in the ice sheet,” he said.

The samples from the Jökalhlaup will be flown back to Hobart later this month and analysis of the ice is expected to take several months.

Note : The above story is based on materials provided by Macquarie University.

Amu Darya River

February 19, 2015

The Amu Darya is a major river in Central Asia. It is formed by the junction of the Vakhsh and Panj rivers and flows into the Aral Sea. In ancient times, the river was regarded as the boundary between Greater Iran and Turan.

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Names

In classical antiquity, the river was known as the Ōxus in Latin and Ὦξος Oxos in Greek—a clear derivative of Vakhsh — the name of the largest tributary of the river. In Vedic Sanskrit, the river is also referred to as Vaksu (वक्षु). The Avestan texts too refer to the River as Yaksha-arte.

In ancient Afghanistan, the river was also called Gozan, descriptions of which can be found in the book “The Kingdom of Afghanistan: a historical sketch By George Passman Tate”. In Middle Persian sources of the Sassanid period the river is known as Wehrōd (lit. “good river”).

The name Amu is said to have come from the medieval city of Āmul, (later, Chahar Joy/Charjunow, and now known as Türkmenabat), in modern Turkmenistan, with Darya being the Persian word for “river”.

Medieval Arabic and Muslim sources call the river Jayhoun (جيحون) which is derived from Gihon, the biblical name for one of the four rivers of the Garden of Eden.

Watershed

About 1,385,045 square kilometres (534,769 sq mi) of land is drained by the Amu Darya into the Aral Sea endorheic basin. This includes most of Tajikistan, the southwest corner of Kyrgyzstan, the northeast corner of Afghanistan, a long narrow portion of eastern Turkmenistan and about half of Uzbekistan. Part of the Amu Darya’s drainage divide in Tajikistan forms that country’s border with China (in the east) and Pakistan (to the south). About 61% of the drainage lies within Tajikistan, Uzbekistan and Turkmenistan, while 39% is in Afghanistan. Of the area drained by the Amu Darya, only about 200,000 square kilometres (77,000 sq mi) actively contribute water to the river. This is because many of the river’s major tributaries (especially the Zeravshan River) have been diverted, and much of the river’s drainage is dominated by outlying desert and steppe.

The abundant water flowing in the Amu Darya comes almost entirely from glaciers in the Pamir Mountains and Tian Shan, which, standing above the surrounding arid plain, collect atmospheric moisture which otherwise would probably escape somewhere else. Without its mountain water sources, the Amu Darya would not contain any water—would not exist—because it rarely rains in the lowlands through which most of the river flows. Throughout most of the steppe, the annual rainfall is about 300 millimetres (12 in).

Note : The above story is based on materials provided by Wikipedia.

ArcGIS 10.2.2

February 18, 2015

Esri’s ArcGIS is a geographic information system (GIS) for working with maps and geographic information. It is used for: creating and using maps; compiling geographic data; analyzing mapped information; sharing and discovering geographic information; using maps and geographic information in a range of applications; and managing geographic information in a database.

The system provides an infrastructure for making maps and geographic information available throughout an organization, across a community, and openly on the Web.

ArcGIS includes the following Windows desktop software:

ArcReader, which allows one to view and query maps created with the other ArcGIS products;
ArcGIS for Desktop, which is licensed under three functionality levels:
ArcGIS for Desktop Basic (formerly known as ArcView), which allows one to view spatial data, create layered maps, and perform basic spatial analysis;
ArcGIS for Desktop Standard (formerly known as ArcEditor), which in addition to the functionality of ArcView, includes more advanced tools for manipulation of shapefiles and geodatabases; or
ArcGIS for Desktop Advanced (formerly known as ArcInfo), which includes capabilities for data manipulation, editing, and analysis.

There are also server-based ArcGIS products, as well as ArcGIS products for PDAs. Extensions can be purchased separately to increase the functionality of ArcGIS.

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Key Features

Conduct Spatial Analysis

Hundreds of tools for performing spatial analysis are included in ArcGIS for Desktop. These tools allow you to turn data into actionable information and automate many of your GIS tasks.

Manage Your Data More Efficiently

With support for more than 70 data formats, you can easily integrate all types of data for visualization and analysis. An extensive set of geographic, tabular, and metadata management, creation, and organization tools are available.

Explore a World of Content

ArcGIS Online is now a part of an ArcGIS for Desktop license. Take advantage of ArcGIS Online to browse the world’s most extensive online geographic resource and discover maps and data about thousands of topics. Combine content any way you want and see it on a map.

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Plants survive better through mass extinctions than animals

February 18, 2015

Dr. Daniele Silvestro, University of Gothenburg finding fossils. Credit: Image courtesy of University of Gothenburg

At least 5 mass extinction events have profoundly changed the history of life on Earth. But a new study led by researchers at the University of Gothenburg shows that plants have been very resilient to those events.
For over 400 million years, plants have played an essential role in almost all terrestrial environments and covered most of the world’s surface. During this long history, many smaller and a few major periods of extinction severely affected Earth’s ecosystems and its biodiversity.

In the upcoming issue of the journal New Phytologist, the team reports their results based on more than 20,000 plant fossils with the aim to understand the effects of such dramatic events on plant diversity. Their findings show that mass extinction events had very different impacts among plant groups. Negative rates of diversification in plants (meaning that more species died out than new species were formed) were never sustained through long time periods. This indicates that, in general, plants have been particularly good at surviving and recovering through tough periods.

“In the plant kingdom, mass extinction events can be seen as opportunities for turnover leading to renewed biodiversity,” says leading author Daniele Silvestro.

Most striking were the results for the Cretaceous-Paleogene mass extinction, caused by the impact of an asteroid off the Mexican coast some 66 million years ago. This event had a great impact on the configuration of terrestrial habitats and led to the extinction of all dinosaurs except birds, but surprisingly it had only limited effects on plant diversity.

Some important plant groups, such as the gymnosperms (including pines, spruce and firs) lost a great deal of their diversity through extinction. On the other hand, flowering plants (angiosperms) did not suffer from increased extinction, and shortly after the impact they underwent a new rapid increase in their diversity. These evolutionary dynamics contributed to make flowering plants dominate today’s global diversity above all other plant groups.

“Mass extinctions are often thought as a bad thing, but they have been crucial in changing the world into how we know it today,” says senior author Alexandre Antonelli.

If that asteroid had not struck the Earth, chances are that large dinosaurs would still be hunting around, mammals would be small and hiding in caves, and humans might never have evolved.

“By studying such extreme events we are trying to learn which groups of organisms and features are more sensitive to changes, so that we can apply this knowledge to protect biodiversity in the face of on-going climate change and human deterioration of natural ecosystems,” concludes Antonelli.

Reference:
Daniele Silvestro, Borja Cascales-Miñana, Christine D. Bacon, Alexandre Antonelli. Revisiting the origin and diversification of vascular plants through a comprehensive Bayesian analysis of the fossil record. New Phytologist, 2015; DOI: 10.1111/nph.13247

Note: The above story is based on materials provided by University of Gothenburg.

Recent research provides new data on chemical gardens, whose formation is a mystery for science

February 18, 2015

This is an image of chemical gardens. Credit: UGR

Recent research which has counted with the participation of the University of Granada Andalusian Institute of Earth Sciences has yielded new data on chemical gardens, mysterious formations produced when certain solid salts (copper sulfate, cobalt chloride) are added to an aqueous solution of sodium silicate.
Self-contained chemical gardens are formed through the self-assembly of mineral precipitates generated during certain chemical reactions, and they produce coloured forms that resemble vegetable structures. The first researcher who watched them was Johann Rudolf Glauber in 1646, and since then their formation has been a veritable mystery for the scientific community.

Besides their popularity in chemistry experiments for massive audiences, self-contained chemical gardens present analogies with a variety of natural systems, such as the ice channels formed underneath sea ice or the hydrothermal chimneys at the bottom of the oceans where it is believed that life on earth could have originated.

Their growth patterns are being studied today fundamentally to produce new self-structuring materials, or to understand their role in the origin of life, thanks to the energy they can store.

To produce a chemical garden in the lab, one typically introduces a metallic salt in an alkaline solution within a container. This leads to the growth of a series of irregular, tubular, multi-coloured structures thanks to the combined action of different physical processes (osmotic pressure, gravity effects, reactions and diffusion)

The fact that these different processes interact in a complex way without any sort of control whatsoever provokes the irregularity, and above all the impossibility of reproducing the obtained three-dimensional forms obtained in this process. This precludes detailed understanding of the growth mechanisms of these structures.

An almost bi-dimensional confined environment

In this context, researchers from the Non-linear Physical Chemistry Unity at the Free University of Brussels, and from the University of Granada Andalusian Institute of Earth Sciences have demonstrated that it is possible to obtain an important collection of reproducible structures by having the chemical gardens grow in a confined, almost bi-dimensional environment, by injecting a reagent inside another one between two horizontal plaques.

The horizontal confinement of the reactor reduces the effects of gravity, while the injection of one reagent within another reduces the effects of osmotic pressure. Besides, the control of the initial concentrations of the reagents, and of the flow of injection allows for the study of the relative importance of chemical processes and transport within the selection of the shape in the precipitate.

Published in the journal PNAS, this study has enabled researchers to obtain in a controlled and reproducible way a large variety of motives, such as flowers, filaments or spirals, thus facilitating a better comprehension of the mechanisms that produce their formation.

For instance, the authors of this study have exploited standard methods for the analysis of bi-dimensional motifs with the aim of elucidating the grown mechanism for the spirals, with the support of an elemental geometric models.

These results provide a new methodology for the analysis of growth in an non-equilibrium situation, aimed at obtaining a better control of the physical and chemical properties of self-assembled solid materials.

Reference:
Florence Haudin, Julyan H. E. Cartwright, Fabian Brau, and A. De Wit
Spiral precipitation patterns in confined chemical gardens
PNAS 2014; published ahead of print November 10, 2014, doi:10.1073/pnas.1409552111

Note : The above story is based on materials provided by University of Granada.

Humans altering Adriatic ecosystems more than nature, study shows

February 18, 2015

The study area (a) and simplified stratigraphic cross section (b) of the uppermost deposits of the Po coastal plain. The stratigraphic intervals assigned to marine isotope stages (MIS) 1 and 5e indicate the Holocene and Late Pleistocene sequences, respectively.

The ecosystems of the Adriatic Sea have weathered natural climate shifts for 125,000 years, but humans could be rapidly altering this historically stable biodiversity hot spot, a University of Florida study says.

The study details a major shift in bottom-dwelling species in Italy’s Po Basin, a region south of Venice known for its ecologically and commercially important shellfish as well as its tourism industry.

“The fossil record suggests that human activities can alter even those ecosystems that have been immune to major changes naturally occurring on our planet,” said the study’s lead author, Michal Kowalewski, the Thompson Chair of Invertebrate Paleontology at the Florida Museum of Natural History on the UF campus.

“We may be witnessing a permanent shift,” Kowalewski said. “This restructuring could have lasting consequences for regional biodiversity, including the overall health of the broader marine ecosystems of the Adriatic.”

Mollusks preserve well in the fossil record and tend to be sensitive to human-caused environmental change, making them a good indicator of marine ecosystem health. The study, appearing online this week in the Proceedings of the Royal Society B, documents rapidly changing marine communities in the northern Adriatic, one of Europe’s most highly developed industrial and agricultural areas. Researchers tracked changes in shellfish communities by examining a collection of more than 100,000 fossil specimens from geological cores drilled in the region. They then compared the fossil data with surveys of present-day marine ecosystems conducted in the last four decades of the 20th century. The fossil record shows 125,000 years ago the Adriatic region’s climate and sea level were similar to today. However, the authors found significant ecosystem changes in the most recent centuries, including a decline in seven out of the 10 historically dominant mollusk species.

The findings echo those of previous studies on Caribbean reef communities.

“The changes found by the study researchers are alarming, but there’s reason to believe that other areas have been even more profoundly affected by the effects of pollution, habitat disturbance, lack of oxygen and climate change,” said Steven Holland, a University of Georgia paleontologist not involved in the study. “This is a clear fingerprint of the effects of humans.”

Reference:
M. Kowalewski, J. M. Wittmer, T. A. Dexter, A. Amorosi, D. Scarponi. Differential responses of marine communities to natural and anthropogenic changes. Proceedings of the Royal Society B: Biological Sciences, 2015; 282 (1803): 20142990 DOI: 10.1098/rspb.2014.2990

Note: The above story is based on materials provided by University of Florida. The original article was written by Stephenie Livingston.

Mapping seascapes in the deep ocean

February 18, 2015

3D Seascape. Credit: Image courtesy of National Oceanography Centre

Researchers at the National Oceanography Centre (NOC) have developed a new, automated method for classifying hundreds of kilometres of the deep sea floor, in a way that is more cost efficient, quicker and more objective than previously possible.

Currently there is very little information about the geographic distribution of life on the sea floor. This is largely because of the practical difficulty in accessing creatures which live at such a great depth in the ocean. However, this research soon to be published in the journal Marine Geology, reveals a new method of estimating this distribution using a combination of: submarine mapping technology, statistics and a ‘landscape’ ecology technique called ‘Niche Theory’, which is generally used on land.

The Niche Theory states that biodiversity is driven by spatial variability in environmental conditions, i.e. the greater the range of habitats, the greater the biodiversity. The lead author of this study, Khaira Ismail from the University of Southampton, has used this concept to create broad-scale, full coverage maps of the sea floor. The objective of these maps is to estimate the location of biodiversity hotspots, by identifying areas where the deep-sea landscapes are relatively more varied.

Dr Veerle Huvenne, from the NOC, said “by informing us of where to look and where to plan more detailed surveys, this new method will help to make our deep-sea research more targeted and efficient, by advancing our understanding of life in the deep ocean, which at the moment is still very limited.”

These maps cover areas approximately 200km across, and have pixel sizes around 25m. They are created using information on the topography and sediment type of the sea floor, collected from a multi-beam echo sounder and a side scan sonar, respectively. The resulting map is then analysed in order to break down the sea floor into a series of zones, using statistical analysis to identify distinct ‘geomorphological terrains’ in an objective and repeatable way.

Khaira said “using statistical methods to identify these ‘terrain zones’ allows us to be more objective than if we were picking them out by hand. This objectivity means that the results are consistent and repeatable, which allows different areas of the sea floor to be compared more easily.”

This research forms part of the €1.4M European Research Council funded CODEMAP project, and was applied in the Lisbon-Setúbal and Cascais Canyons, off the Portuguese coast. These submarine canyons were classified into six marine ‘seascapes’, based on their geomorphological features.

Future work will use submarine robot cameras to take photos and videos of life in the deep-sea areas that have been subjected to this mapping technique. This will allow researchers to start to identify new deep sea habitats.

Reference:
Khaira Ismail, Veerle A.I. Huvenne, Douglas G. Masson. Objective automated classification technique for marine landscape mapping in submarine canyons. Marine Geology, 2015; 362: 17 DOI: 10.1016/j.margeo.2015.01.006

Note : The above story is based on materials provided by National Oceanography Centre.

Petroleum Traps

February 17, 2015

Two types of petroleum traps are; structural and stratigraphic. Structural traps are formed by deformation of reservoir rock, such as by folding or faulting. Stratigraphic traps are formed by deposition of reservoir rock, such as river channel or reef, or by erosion of reservoir rock, such as an angular unconformity

Table of Contents

Structural Trap

Structural trap is a type of geological trap that forms as a result of changes in the structure of the subsurface, due to tectonic, diapiric, gravitational and compactional processes. These changes block the upward migration of hydrocarbons and can lead to the formation of a petroleum reservoir.

Structural traps are the most important type of trap as they represent the majority of the world’s discovered petroleum resources. The three basic forms of structural traps are the anticline trap, the fault trap and the salt dome trap.

Anticlinal trap Photo Copyright © MagentaGreen

Anticlinal (fold) Trap

An anticline is an area of the subsurface where the strata have been pushed into forming a domed shape. If there is a layer of impermeable rock present in this dome shape, then hydrocarbons can accumulate at the crest until the anticline is filled to the spill point – the highest point where hydrocarbons can escape the anticline. This type of trap is by far the most significant to the hydrocarbon industry. Anticline traps are usually long oval domes of land that can often be seen by looking at a geological map or by flying over the land.

Fault Trap

This trap is formed by the movement of permeable and impermeable layers of rock along a fault line. The permeable reservoir rock faults such that it is now adjacent to an impermeable rock, preventing hydrocarbons from further migration. In some cases, there can be an impermeable substance smeared along the fault line (such as clay) that also acts to prevent migration. This is known as clay smear.

Salt dome Trap

Masses of salt are pushed up through clastic rocks due to their greater buoyancy, eventually breaking through and rising towards the surface (see salt dome). This salt is impermeable and when it crosses a layer of permeable rock, in which hydrocarbons are migrating, it blocks the pathway in much the same manner as a fault trap. This is one of the reasons why there is significant focus on subsalt imaging, despite the many technical challenges that accompany it.

Stratigraphic Traps

Stratigraphic traps are formed as a result of lateral and vertical variations in the thickness, texture, porosity or lithology of the reservoir rock. Examples of this type of trap are an unconformity trap, a lens trap and a reef trap.

Two main groups can be recognized :

Primary
stratigraphic traps result from variations in facies that developed during sedimentation. These include features such as lenses, pinch-outs, and appropriate facies changes.

Secondary
stratigraphic traps result from variations that developed after sedimentation, mainly because of diagenesis. These include variations due to porosity enhancement by dissolution or loss by cementation.

Paleogeomorphic traps are controlled by buried landscape. Some are associated with prominences (hills); others with depressions (valleys). Many are also partly controlled by unconformities so are also termed unconformity traps .

Video:

Formation of Hydrocarbon Trap

Reference:
Petroleum Traps , KING ABDULAZIZ UNIVERSITY : GEOL 463.3—RWR-5
Traps , West Virginia University : Structure traps.pdf
Structural trap : From Wikipedia
Stratigraphic Traps : Paleontological Research Institution and its Museum of the Earth
Schlumberger : Structural trap , Stratigraphic trap

Ancient rocks show life could have flourished on Earth 3.2 billion years ago

February 17, 2015

The oldest samples are sedimentary rocks that formed 3.2 billion years ago in northwestern Australia. They contain chemical evidence for nitrogen fixation by microbes. Credit: R. Buick / UW

A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth. But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes — essential to viruses, bacteria and all other organisms — life on the early Earth would have been scarce.
The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet’s oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.

“People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn’t until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse,” said co-author Roger Buick, a UW professor of Earth and space sciences. “Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”

The results were published Feb. 16 in Nature.

The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.

Even the oldest samples, 3.2 billion years old — three-quarters of the way back to the birth of the planet — showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life.

“Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating,” said lead author Eva Stüeken, who did the work as part of her UW doctoral research. “It suggests that these really complicated enzymes apparently formed really early, so maybe it’s not so difficult for these enzymes to evolve.”

Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.

“This is hard evidence that pushes it back a further billion years,” Buick said. Fixing nitrogen means breaking a tenacious triple bond that holds nitrogen atoms in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of nitrogen-fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth — before the atmosphere contained oxygen to weather rocks — is more mysterious.

The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of oxygen that reacted with the rock to release molybdenum to the water.

“We’ll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited,” Buick said. “Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago.”

Future work will look at what else could have limited the growth of life on the early Earth. Stüeken has begun a UW postdoctoral position funded by NASA to look at trace metals such as zinc, copper and cobalt to see if one of them controlled the growth of ancient life.

Reference:
Eva E. Stüeken, Roger Buick, Bradley M. Guy, Matthew C. Koehler. Isotopic evidence for biological nitrogen fixation by molybdenum-nitrogenase from 3.2 Gyr. Nature, 2015; DOI: 10.1038/nature14180

Note : The above story is based on materials provided by University of Washington. The original article was written by Hannah Hickey.

Earthquakes in Australia are a rare but real hazard

February 17, 2015

Buckled railway lines caused by the 1968 earthquake near Meckering in Western Australia. Credit: Alice Snooke/Geosciences Australia

Australia is generally regarded as a flat and seismically inert continent that is safe from any serious earthquake hazard. While this is generally true, we do occasionally experience moderate earthquakes, with a magnitude greater than 5.

This fact was witnessed first hand by the residents in Bundaberg and Brisbane, who at 2am (AEDT) yesterday morning felt a magnitude 5.2 earthquake and several smaller aftershocks.
While this earthquake was thankfully small, the world has witnessed several destructive earthquakes in the recent past. This highlights the fact that natural disasters are indiscriminate to political boundaries, while emergency responses are now globally coordinated.

In 2004, the magnitude 9.2 Great Sumatra earthquake – the second largest in recorded history – resulted in a tsunami that killed over 200,000 people.

In 2011, around 230,000 people died following a magnitude 7.0 earthquake in Haiti.

In the same year, magnitude 9.0 Tōhoku earthquake off the east coast of Japan spawned a tsunami, which resulted in around 19,000 deaths and massive infrastructure damage.

A magnitude 8.8 earthquake in Chile in 2010 was fortunate to account for only 500 lives. However, in 2008, the magnitude 8.0 Sichuan earthquake in China killed as many as 87,000 people, leaving up to five million homeless.

The stark variation in casualties reflect not only the magnitude, location and depth of the earthquake, but the population density and strength of infrastructure foundations.

Many people also don’t realise that the moment magnitude scale, or “Richter scale”, is a logarithmic measure of shaking amplitude. This means a magnitude 5 earthquake has a shaking amplitude ten times that of a magnitude 4. This converts to 32 times more energy released for a one-fold increase in moment magnitude, and approximately a 1,000-fold increase for a difference of 2.

To put this in perspective, the 7.2 event in Meereberrie was 1,000 times more powerful than the 5.2 event experienced in Bundaberg yesterday, while the 9.2 Great Sumatran earthquake was 1 million times more powerful.

Table of Contents

Beneath terra Australis

The earthquake could have caused damage up to 15km away, and could have been felt by people up to 187km away from the epicentre near Eidsvold. Credit: Geosciences Australia

Earthquakes in Australia have also resulted in significant damage and loss of life. This was certainly the case with the magnitude 5.6 Newcastle earthquake in 1989, which killed 13 people and resulted in a $4 billion damage bill.

Adelaide is the most earthquake prone capital in Australia. It experienced a magnitude 5.4 earthquake in 1954 that caused over A$1 billion of damage in today’s money.

The largest earthquake recorded in Australia was a magnitude 7.2 in Meeberrie in 1941, some 500 km away from Perth. Apart from cracking all the walls of the Meeberrie homestead and some minor damage in Perth, there was no significant damage from this event simply due to the lack of any nearby population centre.

The earthquakes in Australia are a particularly mysterious type, referred to as “intra-plate” earthquakes. These occur within the interior of tectonic plates rather than at plate boundaries – such as Japan, Indonesia, New Zealand, Chile and the Himalaya – where most of the worlds earthquakes occur.

Unlike earthquakes at plate boundaries, the mechanisms driving intraplate earthquakes are poorly understood. Plate boundaries are either convergent (colliding), divergent (separating) or transform (sliding past one another), and together these account for about 90% of the worlds seismicity.

The question of what drives intraplate deformation far from the influence of plate boundaries has global significance, as they often occur in regions that are not well prepared for such events.

To understand intraplate deformation we must have accurate data relating to the current orientation of the Australian stress field. This can only be determined by monitoring borehole breakouts or from earthquakes larger than magnitude 5. Until recently there has been very little detailed mapping of neotectonic features in Australia.

Earthquake activity in our region since 1973, showing small clusters of seismically active regions near Perth, Adelaide and the east coast. Credit: Solomon Buckman, Author provided

Geoscience Australia initiated a trenching program several years ago, which revealed several young fault systems 100 km north of Adelaide. These indicate that the area may well have experienced earthquakes larger than the 1954 earthquake in the not so distant past.

Very little is known about the nature and recurrence intervals of these faults. This is largely due to the fact that the fault traces are usually covered by a thin veneer of soil and sediment that effectively conceals them from view.

New optically stimulated luminescence (OSL) dating techniques applied to the buried sediment that accumulates at the toe of a fault scarp are shedding light on the timing of pre-historic earthquakes and revealing that the Mount Lofty and Flinders ranges in South Australia are quite young geomorphic features and not necessarily the denuded core of an ancient mountain range as once thought.

Plate margins near Australia. The black dots are earthquake epicentres and the red triangles are volcanoes. Credit: USGS

Hit predictions

Although we will never be able to “predict” when an earthquake will occur with enough precision to practically evacuate cities or towns, the study of ancient earthquakes (paleoseismology) is an essential tool in extending our knowledge of pre-historic (1973) earthquakes in areas where recurrence intervals along major faults may be in the order of tens of thousands of years.

The issue of uncertainty in earthquake predictions was brought to the fore recently when six Italian seismologists were convicted of manslaughter for giving inaccurate advice before an earthquake that struck the town of L’Aquila in April 2009, killing more than 300 people.

Much to the relief of the world’s geological community, they were acquitted in November 2014 after an appeal, but it highlights the importance of communicating complex natural phenomena to the general public.

While the earthquake in Queensland this week thankfully caused little damage, we still need a longer term perspective in terms of earthquake mitigation, and also in terms of determining the fundamental driving mechanisms of intra-plate tectonism.

We need to talk to communities about the risk of earthquake activities, even in apparently stable regions like Australia. This is because even we are not immune to the tectonic forces that are driving our continent northward at the incredible velocity of about 6 cm per year – making Australia the fastest moving continent.

Emergency earthquake responses are also now a globally coordinated activity involving numerous countries and organisations. That means we all have an important role to play.

Note : The above story is based on materials provided by The Conversation
This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).

Carbonates make diamonds grow in the Earth’s mantle

February 16, 2015

Short-lived splendour: Diamonds are caught up in a cycle of growth and decay in the Earth’s interior. (Photo: paloetic/flickr)

Lava that is almost as free-flowing as water and, when it cools down, as pale as limestone: the Ol Doinyo Lengai in northern Tanzania is the only active volcano in the world that produces so-called carbonatite lava. Unlike conventional lava, the majority of this lava consists not of molten silicates but of molten carbonates. Volcanoes of this kind are found along rift valleys where the continental plates gradually break apart and new oceans are formed.

Table of Contents

Diamond from lime and iron

These carbonate melts, among other things, form when limestones enter the Earth’s mantle. This occurs as a result of subduction, when old oceanic crust plunges down below an adjoining crustal plate. By means of high-pressure experiments in the laboratory, postdoc Arno Rohrbach and ETH Zurich Professor Max Schmidt from the Institute of Geochemistry and Petrology of ETH Zurich studied how the oxidised carbon contained in the carbonates behaves in the Earth’s mantle, and in so doing they made an exciting discovery: at a depth of more than 200 kilometres, the submerged carbonates of the oceanic crust reach their melting point, which is 300 to 400 degrees lower than that of silicates. A carbonatite melt is formed and migrates from the subducted oceanic crust into the surrounding mantle, where it causes partial melting therein. However, because the Earth’s mantle is strongly chemically reducing and contains elemental metallic iron, the CO2 in the carbonatite melt reacts with the elemental iron. This causes diamonds to form.

Earlier studies have already shown that carbonates in the Earth’s mantle cause the surrounding mantle to melt at relatively lower temperatures at pressure in excess of 2.5 gigapascals, but these studies focused exclusively on the oxidised state of the carbonates. However, the ETH Zurich researchers write in their study, which was recently published on-line in “Nature”, that in order to understand what happens in the significantly reduced deeper mantle of the Earth it is necessary to consider the redox equilibrium between oxidised carbonates and the reduced metal-containing deeper mantle.

“Minerals in the Earth’s mantle such as garnet and perovskite preferentially incorporate trivalent iron during their formation”, says Max Schmidt. Part of the otherwise doubly positively charged iron is oxidised for this purpose, while another part that is half the amount of the trivalent iron is simultaneously reduced to elemental iron. Because metallic iron and carbon dioxide are incompatible, the iron metal is oxidised and the carbon dioxide is reduced to pure carbon. Thus, diamonds crystallise out of the carbonate melt at a pressure of more than 10 gigapascals and temperatures of 1400 to 1700 degrees Celsius, consequently the carbonate melt solidifies. Thereafter only triply and doubly positively charged iron together with the diamonds remain in these mantle domains in the transition zone between the upper and lower mantle at a depth between about 410 and 660 kilometres.

The carbon cycle in the Earth’s interior is more complex

However, as a result of convection in the Earth’s mantle over hundreds of millions of years, the “agglomerates” of diamonds, which cover a distance of between one and ten centimetres per year, can be transported into the lower mantle down to a depth well in excess of 2000 kilometres, and can rise up again from there. During the uprise, the diamonds remain stable until they pass back through the transition zone from the lower to the upper mantle of the Earth, in which both the chemical equilibrium and the pressure and temperature conditions change again: here the minerals containing trivalent iron – perovskite and garnet – become unstable and release trivalent iron which then reacts with the diamonds. The carbon is re-oxidised in this process, the diamonds are destroyed and the trivalent iron is reduced to divalent iron. Carbonate melts can form again due to the presence of carbon dioxide, and the divalent iron is incorporated into the minerals olivine and pyroxene, which make up the majority of the upper mantle.

This enabled the researchers to show not only how and where carbonatite melts are formed in the Earth’s mantle. They also demonstrated how the carbon cycle from the Earth’s surface down to its interior functions: from carbon dioxide transported with carbonates into the interior, reduced to pure carbon and finally oxidised back to carbon dioxide as it rises. The resulting carbonatite melt, most of which is normally dissolved in a silicate melt at crustal pressures, ultimately brings the carbon dioxide back to the surface of the Earth through active volcanoes such as the Ol Doinyo Lengai.

Reference:
Rohrbach A &Schmidt M: Redox freezing and melting in the Earth’s deep mantle, Nature (2011), DOI:10.1038/nature09899, published online 23 March 2011

Note : The above story is based on materials provided by ETH Zurich.

Archaeocyatha

February 16, 2015

Archeocyathids from the Poleta formation, eastern California

Archaeocyatha or archaeocyathids (“ancient cups”) are extinct, sessile, reef-building marine organisms of warm tropical and subtropical waters that lived during the early (lower) Cambrian period. It is believed that the centre of the Archaeocyatha origin is in East Siberia, where they are first known from the beginning of the Tommotian Age of the Cambrian, 525 million years ago (mya). In other regions of the world, they appeared much later, during the Atdabanian, and quickly diversified into over a hundred families. They became the planet’s very first reef-building animals and are an index fossil for the Lower Cambrian worldwide.

Table of Contents

Preservation

The remains of Archaeocyatha are mostly preserved as carbonate structures in a limestone matrix. This means that the fossils cannot be chemically or mechanically isolated, save for some specimens that have already eroded out of their matrices, and their morphology has to be determined from thin cuts of the stone in which they were preserved.

Geological history

Today, the archaeocyathan families are recognizable by small but consistent differences in their fossilized structures: Some archaeocyathans were built like nested bowls, while others were as long as 300mm. Some archaeocyaths were solitary organisms, while others formed colonies. In the beginning of the Toyonian Age around 516 mya, the archaeocyaths went into a sharp decline. Almost all species became extinct by the Middle Cambrian, with the final-known species, Antarcticocyathus webberi, disappearing just prior to the end of the Cambrian period. Their rapid decline and disappearance coincided with a rapid diversification of the Demosponges.

The archaeocyathids were important reef-builders in the early to middle Cambrian, with reefs (and indeed any accumulation of carbonates) becoming very rare after the group’s extinction until the diversification of new taxa of coral reef-builders in the Ordovician.

Morphology

The typical archaeocyathid resembled a hollow horn coral. Each had a conical or vase-shaped porous skeleton of calcite similar to that of a sponge. The structure appeared like a pair of perforated, nested ice cream cones. Their skeletons consisted of either a single porous wall (Monocyathida), or more commonly as two concentric porous walls, an inner and outer wall separated by a space. Inside the inner wall was a cavity (like the inside of an empty ice cream cone). At the base, these pleosponges were held to the substrate by a holdfast. The body presumably occupied the space between the inner and outer shells (the intervallum).

Ecology

Flow tank experiments suggest that archaeocyathan morphology allowed them to exploit flow gradients, either by passively pumping water through the skeleton, or, as in present-day, extant sponges, by drawing water through the pores, removing nutrients, and expelling spent water and wastes through the pores into the central space.

Distribution

The archaeocyathans inhabited coastal areas of shallow seas. Their widespread distribution over almost the entire Cambrian world, as well as the taxonomic diversity of the species, might be explained by surmising that that they were planktonic during their larval stage.

Their phylogenetic affiliation has been subject to changing interpretations, yet the consensus is growing that the archaeocyath was indeed a kind of sponge, thus sometimes called a pleosponge. But some invertebrate paleontologists have placed them in an extinct, separate phylum, known appropriately as the Archaeocyatha. However, one cladistic analysis suggests that Archaeocyatha is a clade nested within the phylum Porifera (better known as the true sponges).

Note : The above story is based on materials provided by Wikipedia.

How carbonates behave in the Earth’s interior

February 16, 2015

Carbonates are the most important carbon reservoirs on the planet. But what role do they play in the Earth’s interior? How do they react to conditions in the Earth’s mantle? These are the questions being asked by a group of scientific researchers from Frankfurt, Bayreuth, Berlin/Potsdam, Freiberg and Hamburg, in a project funded by the DFG. The Research Unit brings together experts from various geoscience disciplines and cutting edge technology.

The Earth has an average radius of around 6,400 kilometers. However, the deepest borehole thus far drilled has only reached a depth of twelve kilometers. And even with huge technical advances, it is unthinkable that we will ever be able to carry out empirical research on the deepest layers, according to Björn Winkler, Professor of Crystallography at the Goethe University Frankfurt and coordinator of the new Research Unit. “We can only get an idea of the conditions in the Earth’s interior by combining experiments and model calculations”, he explains. While we already have detailed knowledge of silicates, which are a key component of the earth’s mantle, very little research on carbonates has been done to date. “The composition of the earth can be explained without carbonates – but the question is, how well?”, continues Winkler.

“Structures, Properties and Reactions of Carbonates at High Temperatures and Pressures” is the title of the project being funded by the DFG as of mid-February. “We want to understand how the Earth works,” is the way Winkler describes the primary research goal of the approximately 30 scientists and their teams. What possibilities our planet has for storing carbon, how much carbon there actually is on the earth – the entire carbon cycle is still a complete mystery.

The research group, which combines seven individual projects, is focusing its attention on the Earth’s mantle: the 2,850 kilometer thick middle layer in the internal structure of the earth. The aim is to come to a better understanding of the phase relationships, crystal chemistry and physical properties of carbonates. To that end, the plan is to simulate the conditions of the mantle transition zone and the lower earth mantle below it – namely very high temperatures and very high pressure. Each of the seven projects examines a different aspect; for example the carbonate calcite, or the combination of carbonates with iron or silicates, or the behavior of carbonates under shock.

Winkler and his team have been dealing with this issue for six years already. His colleague, Dr. Lkhamsuren Bayarjargal has already been awarded the Max-von-Laue Prize from the German Association of Crystallography for his work with high-power lasers, and has received funding from the Focus Program of the Goethe University. The nationwide collaboration among the researchers is not an entirely new phenomenon either. The DFG funding will enable them to build special equipment to simulate the conditions in the Earth’s mantle. This research apparatus includes diamond anvil cells, capable of producing pressures a million times greater than atmospheric pressure, and high-power lasers that can generate temperatures of up to 5,000 degrees Celsius. Calculations have shown that these are the conditions that prevail in the Earth’s mantle.

The tiniest amounts of a carbonate are enough for an experiment. During the experiment, the substance is exposed to the respective conditions while the researchers examine it for any changes. A variety of techniques are used for this, such as Raman spectroscopy in Frankfurt, and infrared spectroscopy in Potsdam. “If we come to the same conclusions using different methods, we will know that we have got it right,” says Prof. Winkler.

Note : The above story is based on materials provided by Goethe University.

Historic tide gauge data to shed light on ancient tsunamis

February 16, 2015

Chart from Valetta, Malta, 2nd April 1872, after undergoing conservation, showing the ‘seiching’

By restoring historic tide gauge data from Malta and making it available to the public, researchers at the National Oceanography Centre (NOC) and the UKHO hope to shed new light on past tsunamis and climate change in the Mediterranean.
A tide gauge, installed in the Maltese port of Valetta in 1871, offers the only continuous record of the sea level in the Southern Mediterranean that goes back further than fifty years. However, some of the paper records it produced have deteriorated.

The project coordinator, NOC’s Elizabeth Bradshaw said, “there are a limited number of long-term records of climate data in the world, so rescuing and recovering data is vital for answering questions on climate change and oceanography.”

This project is being run from the British Oceanographic Data Centre (BODC) which is a National Facility, within the NOC, that maintains and distributes marine data.

The Department for Business, Innovation and Skills (BIS) have provided £32,000 from its’ ‘Breakthrough Fund’1 to NOC and the UKHO in order to restore these records and make them available to the public. They hope to digitise the data via a citizen science activity, once this project is complete. Once digitised, scientists will be able to use the data to look for evidence of past tsunamis and climate change.

Professor Kevin Horsburgh, from the NOC, said “Preserving long term data records like these is essential for our understanding of sea level change. The data allows scientists to identify the mechanisms that contribute to long term variability of sea level, as well as to measure the impact of each process. These variations range from long term tidal changes through to century scale change due to climate change”

While modern tide gauges typically only calculate the sea level once every fifteen minutes, this historic analogue gauge made a continuous recording. It worked using a float on the water that, via a system of pulleys and cogs, moved a pen up and down a paper-wrapped drum in a way that reflected the changing sea level.

The British Navy installed the gauge to ensure ships got safely in and out of the harbour. In 1877 the Astronomer Royal George Airy2 used the data from this gauge to write about the particularly interesting tidal signal at Valetta. This signal is caused by the ocean water sloshing back and forth across the Mediterranean basin much as it does in a bath. The gauge remained operational until 1926.

Note : The above story is based on materials provided by National Oceanography Centre.

A universal trend?

Virtual evolution

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Watershed

Key Features

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System Requirements

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An almost bi-dimensional confined environment

Structural Trap

Anticlinal (fold) Trap

Fault Trap

Salt dome Trap

Stratigraphic Traps

Two main groups can be recognized :

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Beneath terra Australis

Hit predictions

Diamond from lime and iron

The carbon cycle in the Earth’s interior is more complex

Preservation

Geological history

Morphology

Ecology

Distribution

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