Earthquake rattles Tamworth

Enormous volcanic eruptions with potential to end civilizations may have surprisingly short fuses, researchers have discovered. These eruptions are known as super-eruptions because they are more than 100 times the size of ordinary volcanic eruptions like Mount St. Helens.

They spew out tremendous flows of super-heated gas, ash and rock capable of blanketing entire continents and inject enough particulate into the stratosphere to throw the global climate into decade-long volcanic winters.

In fact, there is evidence that one super-eruption, which took place in Indonesia 74,000 years ago, may have come remarkably close to wiping out the entire human species.

Geologists generally believe that a super-eruption is produced by a giant pool of magma that forms a couple of miles below the surface and then simmers for 100,000 to 200,000 years before erupting. But a new study suggests that once they form, these giant magma bodies may only exist for a few thousand years, perhaps only a few hundred years, before erupting.

“Our study suggests that when these exceptionally large magma pools form they are ephemeral and cannot exist very long without erupting,” said Guilherme Gualda, the assistant professor of earth and environmental sciences at Vanderbilt University who directed the study, which appears in the May 30 issue of the journal PLoS ONE.

The study was performed on the remnants of the Bishop Tuff, the Long Valley super-eruption that occurred in east-central California 760,000 years ago. Using the latest methods for dating the process of magma formation, Gualda and his colleagues found several independent lines of evidence that indicate the magma pool formed within a few thousand years, perhaps within a few hundred years, before it erupted, covering half of the North American continent with smoldering ash.

These giant magma pools tend to be shaped like pancakes and are 10 to 25 miles in diameter and one half to three miles deep. In the beginning, the molten rock in these pools is largely free from crystals and bubbles.

After they form, however, crystals and bubbles form gradually and progressively change the magma’s physical and chemical properties, a process that halts when an eruption takes place.

As far as geologists can tell, no such giant crystal-poor magma body currently exists that is capable of producing a super-eruption. The research team believes this may be because these magma bodies exist for a relatively short time rather than persisting for hundreds of thousands of years as previously thought.

According to Gualda, the estimates for the 100,000 year-plus lifetimes of these giant magma bodies appears to be an artifact of the method that geologists have used to make them. The measurements have been made using zircon crystals.

Zircons are commonplace in volcanic rocks and they contain small amounts of radioactive uranium and thorium, which decay into lead at a set rate, allowing scientists to accurately determine when the crystals formed. They are extremely useful for many purposes because they can survive most geologic processes.

However, the fact that zircons can withstand the heat and the forces found in a magma chamber means that they are not good at recording the lifetimes of crystal-poor magma bodies.

Gualda and his colleagues took a different approach in his studies of the Bishop Tuff. They determined crystallization rates of quartz – the most abundant mineral in the deposits – to gather information about the lifespan of these giant magma bodies.

They developed four independent lines of evidence that agreed that the formation process took less than 10,000 years and most likely between 500 to 3,000 years before the eruption.

They suggest that the zircon crystal measurements record the extensive changes that take place in the crust required before the giant magma bodies can begin forming as opposed to the formation itself.

“The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem,” said Gualda.

Instead of concluding that there is virtually no risk of another super-eruption for the foreseeable future because there are no suitable magma bodies, geologists need to regularly monitor areas where super-eruptions are likely, such as Yellowstone, to provide advanced warning if such a magma body begins to form.

According to a 2005 report by the Geological Society of London, “Even science fiction cannot produce a credible mechanism for averting a super-eruption. We can, however, work to better understand the mechanisms involved in super-eruptions, with the goal of being able to predict them ahead of time and provide a warning for society. Preparedness is the key to mitigation of the disastrous effects of a super-eruption.”

Vanderbilt doctoral student Ayla S. Pamukcu, Mark S. Ghiorso of OFM Research, and Alfred T. Anderson Jr.,Stephen R. Sutton and Mark L. Rivers from the University of Chicago participated in the study, which was supported by grants from the National Science Foundation

In the depths of the earth, it is anything but peaceful: large quantities of liquids carve their way through the rock as fluids, causing magma to form. A research team led by the University of Munster, has shown that the fluids flow a lot faster through solid rock than previously assumed. In the Chinese Tian Shan Mountains, fluids pushed their way to the earth’s mantle from great depths in just 200 years rather than in the course of tens or even hundreds of thousands of years.

The researchers from Munster, Kiel, Bochum, Erlangen, Bethlehem (USA) and Lausanne (Switzerland) present their findings, based on an innovative combination of fieldwork, geochemical analysis and numerical calculations, in the current issue of the journal Nature Geoscience. The RUB geoscientists are experts in determining time scales using numerical models.

How the “Ring of Fire” is formed
When tectonic plates move towards each other and push over each other at the edges, so-called subduction zones are formed. The descending plate is heated and continuously releases the water stored in its rocks as fluid.

The fluid penetrates the earth’s mantle, which is located above the descending plate. The fluids thus lower the melting point of the mantle rocks, and the liquid rock formed rises to the volcanoes as magma.

This magma feeds the many volcanoes throughout the world that occur along the convergent plate boundaries and form the “Ring of Fire”, a volcanic belt that encircles the Pacific Ocean. The fluids are commonly assumed to flow through the rock in a defined flow system. Geologists call these structures veins.

Only two hundred years
During field work in the Chinese part of the Tian Shan Mountains (Celestial Mountains), the research team found structures in the rocks they were studying which can be ascribed to massive fluid flows at great depth.

“Our investigation has shown that a great deal of fluid must have flowed through a rock vein at about 70 km depth and that this fluid has obviously already covered a distance of several hundred meters or more – the transport of such large quantities of fluid over such a great distance has not been demonstrated by anyone before us” explains Timm John from the Institute for Mineralogy, University of Munster.

“And the most exciting thing is that this amount of fluid flowed through the rock in what is for geological processes a very short time, only about two hundred years”, adds Nikolaus Gussone of the same institute.

Like in a reservoir
The release of fluids from minerals in the descending plates is a large-scale and continuous process that takes place at depths up to two-hundred kilometres and takes millions of years. During this time, the fluids first accumulate.

As the researchers have now shown for the first time, the released fluids then flowed through the plate on their way to the mantle in pulses in a relatively short time along defined flow paths. “It’s like a reservoir that continuously fills and then empties in a surge through defined channels” Timm John points out.

“The fluid release is focused in space and time, and is much faster than expected – almost like a jet through solid rock”.

The researchers hope to be able to show the spatial and temporal correlations between such fluid pulses and volcanic activity in future studies. It is also possible that such focused fluid releases are associated with the occurrence of earthquake events in subduction zones. To be able to demonstrate such relations, however, intensive research is still needed.

RUB experts for time scales
The RUB’s petrologists were involved in modelling the chemical data. This enabled the research team to determine the time it took the fluids to make their way to the mantle.

Determining the time scales of various geological processes is a particular expertise of Bochum’s petrologists. Among other things, they use minerals and rocks with zones that exhibit a different chemical composition.

T. John et al. (2012): Volcanic arcs fed by rapid pulsed fluid flow through subducting slabs. Nature Geoscience, doi: 10.1038/NGEO1482

Shopping trolleys flung in Perth tornado

The current theory of continental drift provides a good model for understanding terrestrial processes through history. However, while plate tectonics is able to successfully shed light on processes up to 3 billion years ago, the theory isn’t sufficient in explaining the dynamics of the earth and crust formation before that point and through to the earliest formation of planet, some 4.6 billion years ago.

This is the conclusion of Tomas Naaeraa of the Nordic Center for Earth Evolution at the Natural History Museum of Denmark, a part of the University of Copenhagen. His new doctoral dissertation has just been published by the esteemed international scientific journal, Nature.

“Using radiometric dating, one can observe that the Earth’s oldest continents were created in geodynamic environments which were markedly different than current environments characterised by plate tectonics.

Therefore, plate tectonics as we know it today is not a good model for understanding the processes at play during the earliest episodes of the Earths’s history, those beyond 3 billion years ago.

There was another crust dynamic and crust formation that occurred under other processes,” explains Tomas Naeraa, who has been a PhD student at the Natural History Museum of Denmark and the Geological Survey of Denmark and Greenland – GEUS.

Plate tectonics is a theory of continental drift and sea floor spreading. A wide range of phenomena from volcanism, earthquakes and undersea earthquakes (and pursuant tsunamis) to variations in climate and species development on Earth can be explained by the plate tectonics model, globally recognized during the 1960′s. Tomas Naeraa can now demonstrate that the half-century old model no longer suffices.

“Plate tectonics theory can be applied to about 3 billion years of the Earth’s history. However, the Earth is older, up to 4.567 billion years old. We can now demonstrate that there has been a significant shift in the Earth’s dynamics.

Thus, the Earth, under the first third of its history, developed under conditions other than what can be explained using the plate tectonics model,” explains Tomas Naeraa. Tomas is currently employed as a project researcher at GEUS.

Central research topic for 30 years
Since 2006, the 40-year-old Tomas Naeraa has conducted studies of rocks sourced in the 3.85 billion year-old bedrock of the Nuuk region in West Greenland. Using isotopes of the element hafnium (Hf), he has managed to shed light upon a research topic that has puzzled geologists around the world for 30 years.

Naeraa’s instructor, Professor Minik Rosing of the Natural History Museum of Denmark considers Naeraa’s dissertation a seminal work: “We have come to understand the context of the Earth’s and continent’s origins in an entirely new way. Climate and nutrient cycles which nourish all terrestrial organisms are driven by plate tectonics.

So, if the Earth’s crust formation was controlled and initiated by other factors, we need to find out what controlled climate and the environments in which life began and evolved 4 billion years ago.

This fundamental understanding can be of great significance for the understanding of future climate change,” says Minik Rosing, who adds that: “An enormous job waits ahead, and Naeraas’ dissertation is an epochal step.”

Tomas Naeraas’ dissertation, “Hafnium isotope evidence for a transition of continental growth 3.2 Gyr ago” was published in Nature May 31.

Thunderstorms have a significant effect on the formation of ozone. Nitrogen oxide is produced as a result of lightning; this in turn yields ozone at altitudes of 10 kilometres. Strong updraughts in thunderstorms also transport emissions from the ground into the upper atmosphere. But how significant is this effect – compared to aviation, for example?

Researchers at the German Aerospace Center, in collaboration with the US National Center for Atmospheric Research (NCAR), NASA and other partners, are studying such questions. To this end, they will be conducting measurement flights in the United States until mid-June. The researchers are looking to increase the existing body of data and gain a better understanding of the processes that take place in thunderstorms.

“Thunderstorms are like vacuum cleaners,” explains Heidi Huntrieser from the DLR Institute of Atmospheric Physics. The DLR project leader is supervising the measurement flights in the United States.

“Thunderstorms suck air up from the ground, sometimes at speeds surpassing 100 kilometres per hour, and carry it to an altitude of about 10 kilometres, to what is known as the ‘anvil region’. This is the mushroom-shaped layer high above the storm, where the air can only flow horizontally and hardly upwards at all.”

If polluted air, such as that from vehicle emissions on the ground, is transported to this region, the chemistry of these emissions is altered by the low temperatures, differing humidity and more intense solar radiation there; they take much longer to break down, and the production of ozone is increased. “At these altitudes, nitrogen oxide can produce up to 10 times as much ozone as on the ground,” says Huntrieser.

Huntrieser and her project partners intend to use the measurements to increase the existing data pool.

“Previous measurements lead to the conclusion that global aviation produces about one teragram of nitrogen oxide per year, but thunderstorms are responsible for about five times as much. All nitrogen oxide sources jointly contribute about 50 teragrams of nitrogen oxide to the atmosphere each year, so thunderstorms are responsible for about 10 percent,” explains Huntrieser. A teragram is 10 to the power of 12.

New model simulations show that thunderstorms exert a great influence on ozone. “These were somewhat surprising results,” says Huntrieser. “Now we need more measurement data to confirm this.”

Use of three research aircraft
Three research aircraft are being used for the mission: the DLR Falcon research aircraft will take measurements at an altitude of 10 kilometres, while the American HIAPER research aircraft will take measurements at up to 15 kilometres. A DC-8, a much larger aircraft, will mainly operate at lower altitudes. “Our ambitious goal is for all the aircraft to operate simultaneously at different altitudes in the vicinity of thunderstorms. It would be a first,” says Huntrieser.

Influence exerted by different types of lightning
Besides the transportation processes from the ground to the upper atmosphere, the studies will focus on the influence exerted by different types of lightning. There are relatively short lightning bolts a few kilometres long, and some that stretch horizontally over a distance of 100 kilometres or more.

The formation of lightning also depends on the type of storm; previous measurements over Europe indicate that storms with large amounts of hail and frozen rain that occur at mid-latitudes can contain relatively more and sometimes longer lightning bolts.

By comparison, measurements in tropical storms in Brazil indicate fewer ice particles, more cloud droplets and many – but shorter – lightning bolts. Previous measurements also indicate that less nitrogen oxide per lightning bolt is produced in storms with shorter lightning bolts than in those with longer lightning bolts. Due to the varied climatic conditions in the United States, the researchers can investigate both types of storms.

Over Alabama there are storms with less ice, and over Colorado there are those with more frozen rain and hail. Oklahoma is known for its violent storms, also known as supercells, which can also trigger tornadoes.

The research flights are very challenging, but not dangerous for the occupants: “We are not flying directly into the storms. That would be much too dangerous because of the strong turbulence, risk of ice formation, lightning strike and the high wind speeds.

Our measurements are being taken in the calmer anvil region,” explains Huntrieser. The robust Falcon is ideal for this. The DLR pilots have already carried out numerous similar measurements with the research aircraft over Europe, Brazil, Australia and Africa.

The researchers are also breaking some new ground with their measurement flights. Between 12 and 48 hours after the storm has dissipated, the scientists are planning to carry out measurement flights inside the storm’s residual air mass and determine, for example, how much ozone has been produced and how the chemical composition has changed as a result of the storm.

When life began on Earth, iron may have done the job of magnesium, making life possible. On the periodic table of the elements, iron and magnesium are far apart. But new evidence discovered by the NASA Astrobiology Institute (NAI) team at the Georgia Institute of Technology suggests that three billion years ago, iron did the job magnesium does today in helping Ribonucleic acid (RNA), a molecule essential for life, assume the molecular shapes necessary for biology.

The results of the study are scheduled to be published online in the journal PLoS ONE.

There is considerable evidence that the evolution of life passed through an early stage when RNA played a more central role, doing the jobs of DNA and protein before they appeared. During that time, more than three billion years ago, the environment lacked oxygen but had lots of available iron.

“One of the greatest challenges in astrobiology is understanding how life began on Earth billions of years ago when the environment was very different than it is today,” said Carl Pilcher, director of the Astrobiology Institute at NASA’s Ames Research Center Moffett Field, Calif.

“This study shows us how conditions on early Earth may have been conducive to the development of life.”

In the new study, researchers from the Georgia Institute of Technology, Atlanta, used experiments and numerical calculations to show that under early Earth conditions, with little oxygen around, iron can substitute for magnesium in RNA, enabling it to assume the shapes it needs to catalyze life’s chemical reactions. In fact, it catalyzed those reactions better with iron than with magnesium.

“The primary motivation of this work was to understand RNA under plausible early Earth conditions.” said Loren Williams, a professor in the School of Chemistry and Biochemistry at Georgia Tech and leader of the NAI team. “Our hypothesis is that RNA evolved in the presence of iron and is optimized to work with iron.”

Free oxygen gas was almost nonexistent more than three billion years ago in early Earth’s atmosphere. When oxygen began entering the environment as a product of photosynthesis, it turned Earth’s available iron to rust, forming massive banded iron deposits that are still mined today.

When all that iron got tied up in those deposits, it was no longer available. The current study indicates that RNA then began using magnesium, resulting in life as we know it today.

In future studies, the researchers plan to investigate what unique functions RNA can perform with iron that are not possible with magnesium.

In addition to Williams, Georgia Tech School of Biology postdoctoral fellow Shreyas Athavale, research scientist Anton Petrov, and professors Roger Wartell and Stephen Harvey, and Georgia Tech School of Chemistry and Biochemistry postdoctoral fellow Chiaolong Hsiao and professor Nicholas Hud also contributed to this research.

This study was funded by the NASA Astrobiology Institute, a virtual institute located and managed at NASA Ames Research Center, Moffett Field, Calif.

A NASA mission to study the tiny algae vital to the ocean’s food chain has turned up a massive amount of phytoplankton where scientists least expected it — under the Arctic ice.

In a project that uses both satellites and on-site measurements to study this important food source for many of the ocean’s creatures, NASA sent a team to sample the ice pack off the Chukchi Sea along Alaska’s coast.

Researchers aboard the US Coast Guard icebreaker ship, Healy, sampled beneath the 0.8-1.3 meter (2.4-4.0 feet) thick sea ice and found phytoplankton biomass was “extremely high, about fourfold greater than in open water.”

The “massive under-ice bloom” also appeared to extend about 100 kilometers (60 miles) into the ice shelf, until “the waters literally looked like pea soup,” mission leader Kevin Arrigo told reporters.

“We were astonished. It was completely unexpected. It was literally the most intense phytoplankton bloom I have ever seen in my 25 years of doing this type of research,” said Arrigo, a scientist at Stanford University in California.

“Just like the tomatoes in your garden, these and all phytoplankton require light and they require nutrients to grow,” Arrigo explained.

“It has been presumed that there was very little light under the ice and we didn’t expect to see much.”

Known formally as “Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment,” or ICESCAPE, mission scientists went on two expeditions in June-July of 2010 and 2011.

The latest findings are published in the June 7 edition of the journal Science.

Arrigo said the discovery caused “a fundamental shift in our understanding of the Arctic ecosystem,” which was previously believed to be cold and desolate.

Before, the tiny single-celled plants were not believed to grow until the ice melted.

“If you rank all the phytoplankton blooms anywhere in the world by the amount of phytoplankton that is contained in them, the under-ice bloom that we saw during ICESCAPE would finish at the very top of the list,” he added.

“And it was growing beneath a layer of sea ice as thick as a five-year-old child is tall.”

Phytoplankton were scarcer and deeper in the open waters, and were “greatest at depths of 20 to 50 meters (66-164 feet) because of nutrient depletion near the surface,” said the study.

More research is needed to determine how these under-ice phytoplankton affect local ecosystems.

Phytoplankton blooms in the Arctic have been observed to peak as many as 50 days earlier than they did a dozen years ago, a development that could have implications for the larger food web, scientists have said.

“My concern is that if phytoplankton continue to develop and grow earlier and earlier in the year, it is going to become increasingly difficult for those animals that time their life cycle to be in the Arctic… to be there at the right time of year,” Arrigo said.

The microscopic organisms are the base of the food chain and drive the food and reproductive cycles of fish, seabirds and polar bears. How larger animals may react to phytoplankton changes remains unknown.

Phytoplankton are also important because through the process of photosynthesis they remove about half of the harmful carbon dioxide produced by the burning of fossil fuels worldwide.

Previous research has shown the microscopic organisms have been disappearing globally at a rate of one percent per year.

Since 1950, phytoplankton mass has dropped by about 40 percent, most likely due to the accelerating impact of global warming, said a 2010 study in the journal Nature.