The deadly 9.0 earthquake this year in Japan, an 8.8 quake in Chile last year and the 2004 Sumatra-Andaman earthquake that registered 9.0 on the moment magnitude scale have raised alarm in some science and media circles that such events may be linked.

But researchers at the University of California went back over the world's earthquake records dating back to 1900 and found over time there was no statistically significant rise in the number of big quakes 7.0 and higher.

"One has to be careful, because humans have a tendency to see patterns in random sequences," lead author Peter Shearer of the UC Berkeley Department of Statistics told AFP.

"So what we wanted to do here was apply statistical tests to see whether you could say it wasn't just a random sequence of events," said Shearer, whose study appears in the Proceedings of the National Academy of Sciences.

"Those tests showed that you can't say that it is not random; that is, there is not a statistically significant degree of the clustering of events," he said.

Even though there is "a disproportionate number of very large 8.5 earthquakes between 1950 and 1965," there were uncommonly fewer of these during a much longer period afterward from 1965 to 2004.

And although there has been a more frequent rate of 8.0 and larger quakes since 2004, with the last five years in particular at a record high, "there have been rates nearly as high in the past," said the study.

The researchers also looked for any clues from the Earth's crust that could explain why or how big quakes might be linked.

"And the conclusion was no, there isn't a likely physical cause that would link for example a large earthquake in South America to one in Japan," Shearer told AFP.

"The events are just too far away for it to be very likely that there is a physical link between them."

Taken together, the two approaches "suggest that the global risk of large earthquakes is no higher today than it has been in the past," concluded the study.

The findings are in line with a study in Nature Geoscience earlier this year that found the regional hazard of larger earthquakes is increased after a main shock, but the global hazard is not.

That study countered an earlier 2009 paper in Nature that suggested seismic waves might have an effect on distant fault lines, potentially increasing the risk of earthquakes far away.

]]> Tue, 21 FEB 2012 08:57:55 AEST Philadelphia PA (SPX) Dec 08, 2011 - Earthquakes are some of the most daunting natural disasters that scientists try to analyze. Though the earth's major fault lines are well known, there is little scientists can do to predict when an earthquake will occur or how strong it will be. And, though earthquakes involve millions of tons of rock, a team of University of Pennsylvania and Brown University researchers has helped discover an aspect of friction on the nanoscale that may lead to a better understanding of the disasters.

Robert Carpick, a professor who chairs the Department of Mechanical Engineering and Applied Mechanics in Penn's School of Engineering and Applied Science, led the research in collaboration with Terry Tullis and David Goldsby, professors of geological science at Brown.

The experimental and modeling work was conducted by first author Qunyang Li, a postdoctoral researcher in Carpick's group, who has recently been appointed an associate professor in the School of Aerospace at Tsinghua University, China.

Their work will be published in the journal Nature.

The team's research was spurred by an unusual phenomenon that has been observed in both natural and laboratory-simulated faults: materials become more resistant to sliding the longer they are in contact with one another.

This trait is actually fundamental to why earthquakes happen at all. The longer materials are in contact, the stronger the resistance between them and the more violent and unstable the subsequent sliding is. Energy is stored over the time the materials are in contact and is then catastrophically released as an earthquake.

While geologists, physicists and mechanics researchers have studied this phenomenon for decades, the mechanism behind this increase of friction over time has only been hypothesized. There are two main theories as to why this "frictional aging" occurs.

"One hypothesis is that points of contact deform and grow over time - that contact quantity increases," Carpick said. "The other is that bonding at the points of contact strengthens over time - that contact quality increases."

The difficulty in proving that either theory holds true lies in the fact that points of contact are necessarily embedded at the juncture of two materials and are therefore hard to observe. One of the original breakthrough experiments on these theories projected light through transparent materials held together to measure the growth of apparent contact points.

While this lent credence to the contact quantity theory, there was not yet a way to assess the bond strengths at those individual points of contacts or to be sure that the observations were of single points of contacts or clusters of even smaller nanoscale contacts.

It was not until Carpick and Tullis met at a conference designed to bring physicists and mechanics researchers together with geologists that they realized that the tools of the former group could resolve the latter group's contact quality theory. The solution came from moving from the massive scale of earthquakes to the smallest scales imaginable.

"We want to simplify the case," Li said. "So in our experiment we look at only one point of contact: the tip of an atomic force microscope."

An atomic force microscope is an ideal tool for investigating bonding strength where two surfaces meet. Instead of using light, atomic force microscopes measure nanoscale details using an extremely sharp probe tip that is sensitive to the push and pull of individual atoms.

The researchers simulated rock-on-rock contact with silica, a major component in most geological materials. They pressed a silica tip against a silica surface for different lengths of time and then dragged it to measure the amount of friction it experienced.

They repeated these experiments with surfaces made out of different materials: diamond and graphite. Critically, both diamond and graphite are chemically inert. As they don't easily form chemical bonds with silica, any frictional aging that occurred with them would necessarily be due to changing contact area and not increased bond strength.

The results showed a stark difference in the frictional aging between the materials.

"We saw a huge amount of aging with silica on silica. But with silica on diamond or graphite, even though the tip is experiencing about the same stress levels, we see almost no aging," Li said.

"If the increasing contact area was responsible for the increase in frictional aging, you would see similar amounts in these cases. You might even see more aging with diamond because it is stiffer, leading to a slightly higher stress level in the silica, and this would cause more deformation on the tip."

The frictional aging seen in the silica-on-silica experiment was so intense that the researchers had another mystery on their hands: how to reconcile strong aging on the nanoscale with the weaker level seen on the macroscale where earthquakes actually occur.

The solution to that puzzle stems from the fact that not all contact points are created equal. Two different contact points on the same surface that are close to one another will sense each other's presence.

This "elastic coupling," as it is known, means that only a few of the contact points within an area will be resisting the sliding motion at their full capacity; some will have started to slide earlier, and others will slide later. It is too difficult to make them all slide at once.

So, the overall level of resistance relies not only on the maximum resistance any contact point can provide, but also on the small fraction of contact points able to provide this resistance.

"When you take a lot of contact points,"Carpick said, "all of them could have this large amount of aging. But when you try to shear them, you see only a small fraction reach that very high value of friction at any given time. So, you need a very large effect on the level of a single contact point to get even a very modest effect on the macroscopic scale."

While showing that nansocale experiment can provide useful data for these kinds of applications was in itself an important finding for the research team, the ability to reconcile the laboratory data with geologists' observations will have a lasting effect on the field.

"If we can understand the fundamental physics," Tullis said, "then theories and equations based on that physics would have the capability of being extrapolated beyond the laboratory scale. Therefore we could use them with more confidence in all the earthquake modeling that's already being done."

"We're not ruling out the quantity argument, we're just ruling in the quality argument," Carpick said.

"Future research will go to higher stress levels, where maybe contact quantity could start to come into play. We'd also like to look at different temperatures, which matter in the geological context, and do experiments where we can actually watch the contact in real time, using an electron microscope."

]]> Tue, 21 FEB 2012 08:57:55 AEST Berlin, Germany (SPX) Dec 06, 2011 - Geophysicists from Potsdam have established a mode of action that can explain the irregular distribution of strong earthquakes at the San Andreas Fault in California.

As the science magazine Nature reports in its latest issue, the scientists examined the electrical conductivity of the rocks at great depths, which is closely related to the water content within the rocks.

From the pattern of electrical conductivity and seismic activity they were able to deduce that rock water acts as a lubricant.

Los Angeles moves toward San Francisco at a pace of about six centimeters per year, because the Pacific plate with Los Angeles is moving northward, parallel to the North American plate which hosts San Francisco.

But this is only the average value. In some areas, movement along the fault is almost continuous, while other segments are locked until they shift abruptly several meters against each other releasing energy in strong earthquakes. After the San Francisco earthquake of 1906, the plates had moved by six meters.

The San Andreas Fault acts like a seam of the earth, ranging through the entire crust and reaching into the mantle.

Geophysicists from the GFZ German Research Centre for Geosciences have succeeded in imaging this interface to great depths and to establish a connection between processes at depth and events at surface.

"When examining the image of the electrical conductivity, it becomes clear that rock water from depths of the upper mantle, i.e. between 20 to 40 km, can penetrate the shallow areas of the creeping section of the fault, while these fluids are detained in other areas beneath an impermeable layer", says Dr. Oliver Ritter of the GFZ. "A sliding of the plates is supported, where fluids can rise."

These results suggest that significant differences exist in the mechanical and material properties along the fault at depth. The so-called tremor signals, for instance, appear to be linked to areas underneath the San Andreas Fault, where fluids are trapped.

Tremors are low-frequency vibrations that are not associated with rupture processes as they are typical of normal earthquakes. These observations support the idea that fluids play an important role in the onset of earthquakes.

M. Becken et al., "Correlation between deep fluids, tremor and creep along the central San Andreas fault", Nature No. 480, Dec. 2011, pp. 87-90.

]]> Tue, 21 FEB 2012 08:57:55 AEST Melbourne, Australia (SPX) Nov 30, 2011 - Scientists are a step closer to predicting when and where earthquakes will occur after taking a fresh look at the formation of the Andes, which began 45 million years ago.

Published in Nature, research led by Dr Fabio Capitanio of Monash University's School of Geosciences describes a new approach to plate tectonics. It is the first model to go beyond illustrating how plates move, and explain why.

Dr Capitanio said that although the theory had been applied only to one plate boundary so far, it had broader application.

Understanding the forces driving tectonic plates will allow researchers to predict shifts and their consequences, including the formation of mountain ranges, opening and closing of oceans, and earthquakes.

Dr Capitanio said existing theories of plate tectonics had failed to explain several features of the development of the Andes, motivating him to take a different approach.

"We knew that the Andes resulted from the subduction of one plate, under another; however, a lot was unexplained. For example, the subduction began 125 million years ago, but the mountains only began to form 45 million years ago. This lag was not understood," Dr Capitanio said.

"The model we developed explains the timing of the Andes formation and unique features such as the curvature of the mountain chain."

Dr Capitanio said the traditional approach to plate tectonics, to work back from data, resulted in models with strong descriptive, but no predictive power.

"Existing models allow you to describe the movement of the plates as it is happening, but you can't say when they will stop, or whether they will speed up, and so on.

"I developed a three-dimensional, physical model - I used physics to predict the behaviour of tectonic plates. Then, I applied data tracing the Andes back 60 million years. It matched."

Collaborators on the project were Dr Claudio Faccenna of Universita Roma Tre, Dr Sergio Zlotnik of UPC-Barcelona Tech, and Dr David R Stegman of University of California San Diego. The researchers will continue to develop the model by applying it to other subduction zones

]]> Tue, 21 FEB 2012 08:57:55 AEST Blacksburg VA (SPX) Nov 25, 2011 - Researchers the world over are seeking reliable ways to predict earthquakes, focusing on identifying seismic precursors that, if detected early enough, could serve as early warnings.

New research, published this week in the journal Applied Physics Letters, suggests that ozone gas emitted from fracturing rocks could serve as an indicator of impending earthquakes. Ozone is a natural gas, a byproduct of electrical discharges into the air from several sources, such as from lightning, or, according to the new research, from rocks breaking under pressure.

Scientists in the lab of Raul A. Baragiola, a professor of engineering physics in the University of Virginia School of Engineering and Applied Science, set up experiments to measure ozone produced by crushing or drilling into different igneous and metamorphic rocks, including granite, basalt, gneiss, rhyolite and quartz. Different rocks produced different amounts of ozone, with rhyolite producing the strongest ozone emission.

Some time prior to an earthquake, pressures begin to build in underground faults. These pressures fracture rocks, and presumably, would produce detectable ozone.

To distinguish whether the ozone was coming from the rocks or from reactions in the atmosphere, the researchers conducted experiments in pure oxygen, nitrogen, helium and carbon dioxide.

They found that ozone was produced by fracturing rocks only in conditions containing oxygen atoms, such as air, carbon dioxide and pure oxygen molecules, indicating that it came from reactions in the gas. This suggests that rock fractures may be detectable by measuring ozone.

Baragiola began the study by wondering if animals, which seem - at least anecdotally - to be capable of anticipating earthquakes, may be sensitive to changing levels of ozone, and therefore able to react in advance to an earthquake.

It occurred to him that if fracturing rocks create ozone, then ozone detectors might be used as warning devices in the same way that animal behavioral changes might be indicators of seismic activity.

He said the research has several implications.

"If future research shows a positive correlation between ground-level ozone near geological faults and earthquakes, an array of interconnected ozone detectors could monitor anomalous patterns when rock fracture induces the release of ozone from underground and surface cracks," he said.

"Such an array, located away from areas with high levels of ground ozone, could be useful for giving early warning to earthquakes."

He added that detection of an increase of ground ozone might also be useful in anticipating disasters in tunnel excavation, landslides and underground mines.

Baragiola's co-authors are U.Va. research scientist Catherine Dukes and visiting student Dawn Hedges.

]]> Tue, 21 FEB 2012 08:57:55 AEST Charlottesville VA (SPX) Nov 22, 2011 - Researchers the world over are seeking reliable ways to predict earthquakes, focusing on identifying seismic precursors that, if detected early enough, could serve as early warnings. New research, published this week in the journal Applied Physics Letters, suggests that ozone gas emitted from fracturing rocks could serve as an indicator of impending earthquakes.

Ozone is a natural gas, a byproduct of electrical discharges into the air from several sources, such as from lightning, or, according to the new research, from rocks breaking under pressure.

Scientists in the lab of Raul A. Baragiola, a professor of engineering physics in the University of Virginia School of Engineering and Applied Science, set up experiments to measure ozone produced by crushing or drilling into different igneous and metamorphic rocks, including granite, basalt, gneiss, rhyolite and quartz. Different rocks produced different amounts of ozone, with rhyolite producing the strongest ozone emission.

Some time prior to an earthquake, pressures begin to build in underground faults. These pressures fracture rocks, and presumably, would produce detectable ozone.

To distinguish whether the ozone was coming from the rocks or from reactions in the atmosphere, the researchers conducted experiments in pure oxygen, nitrogen, helium and carbon dioxide.

They found that ozone was produced by fracturing rocks only in conditions containing oxygen atoms, such as air, carbon dioxide and pure oxygen molecules, indicating that it came from reactions in the gas. This suggests that rock fractures may be detectable by measuring ozone.

Baragiola began the study by wondering if animals, which seem - at least anecdotally - to be capable of anticipating earthquakes, may be sensitive to changing levels of ozone, and therefore able to react in advance to an earthquake.

It occurred to him that if fracturing rocks create ozone, then ozone detectors might be used as warning devices in the same way that animal behavioral changes might be indicators of seismic activity.

He said the research has several implications.

"If future research shows a positive correlation between ground-level ozone near geological faults and earthquakes, an array of interconnected ozone detectors could monitor anomalous patterns when rock fracture induces the release of ozone from underground and surface cracks," he said.

"Such an array, located away from areas with high levels of ground ozone, could be useful for giving early warning to earthquakes."

He added that detection of an increase of ground ozone might also be useful in anticipating disasters in tunnel excavation, landslides and underground mines.

Baragiola's co-authors are U.Va. research scientist Catherine Dukes and visiting student Dawn Hedges.

]]> Tue, 21 FEB 2012 08:57:55 AEST Taipei (AFP) Nov 14, 2011 - Taiwan said Monday it had put into service its first undersea seismic observation system, giving the island life-saving extra seconds or even minutes to brace for earthquakes and tsunamis.

The Tw$420-million ($14-million) system, built by Japan-based NEC Corp, consists of equipment ranging from ocean-bottom seismographs to tsunami pressure gauges and even underwater microphones.

"The system gives a much clearer picture of what's happening. We can even hear the sounds of dolphins swimming by," Kuo Kai-wen, director of the Seismology Centre, told AFP.

"With the help of this system, we'll be able to attain an average of 10 seconds' extra warning if earthquakes hit off the east coast, and an extra 10 minutes to issue tsunami warnings," he said.

Taiwan is regularly hit by earthquakes, as it lies near the junction of two tectonic plates. In September 1999, a 7.6-magnitude tremor killed around 2,400 people in the deadliest natural disaster in the island's recent history.

The new alert system is centred around a submarine cable beginning at the township of Toucheng in the northeast of Taiwan and stretching for 45 kilometres (27 miles) into the ocean in a roughly easterly direction.

Nearly 70 percent of the earthquakes that strike Taiwan hit this area, according to the seismology centre.

The system is deployed at a depth of around 300 metres (990 feet), sending real-time digital information to land via submarine optical fibre cable 24 hours a day, NEC said in a statement.

Taiwan began considering an undersea alert system after the Indian Ocean tsunami in late 2004 killed almost a quarter of a million people.

Another undersea earthquake, as powerful as that which caused the 2004 disaster, triggered a tsunami that struck Japan in March, leaving about 22,000 dead or missing.

"The power of the two quakes was pretty much the same, but the much lower toll figure in Japan shows that early warning systems are very effective in the battle against unexpected natural disasters," Kuo said.

]]> Tue, 21 FEB 2012 08:57:55 AEST West Lafayette IN (SPX) Oct 25, 2011 - Seismic equipment is being installed throughout Indiana as part of a national program to better understand how and why earthquakes and volcanic events occur, and Purdue University professors and students spent time last summer surveying the state to find the locations best suited for the equipment.

The study is part of EarthScope, a National Science Foundation program that includes more than 400 portable seismometers that record data used to measure earthquakes, monitor the behavior of seismic waves, map movement of the Earth's surface and create images of the North American continent's crust and mantle. These observations will contribute to a better understanding of seismic hazards throughout the nation.

The network of seismometers, called USArray, has been migrating eastward across the United States since 2005. Indiana is among the strip of states from Michigan to Florida where installations began this fall.

Robert Nowack, a Purdue professor of geophysics, said the data collected in Indiana could address significant uncertainties about the New Madrid and Wabash Valley fault zones.

"This will be the most comprehensive seismic deployment in the region ever performed and will give us a much better understanding of the earthquake potential in this state," he said. "The information gathered could help save lives and money by leading to more informed building and bridge designs."

Approximately 23 sites will be installed across the state that include seismic, GPS, and other geophysical instrumentation.

All of the Indiana stations are expected to be installed and operational by late spring of 2012. Each station will remain at a location for two years before it is moved to a new location at the eastern edge of the array. Nearly 2,000 locations across the nation will have been occupied when the project is completed.

Hersh Gilbert, a professor of geophysics who, along with Nowack, led the Purdue siting team in Indiana, said the resulting data will be used to form high-resolution images of the Earth's interior to better understand the geology and tectonics of North America and the structures along which earthquakes occur.

The equipment also will be used for weather research, he said. Barometers and ultrasound sensors also have been added to the equipment to increase the types of data collected and its potential uses.

"This equipment captures everything from an aircraft flying above, a sonic boom in the area to different weather environments, as well as vibrations from earthquakes in the Midwest and around the world," Gilbert said.

"Massive amounts of data are being recorded, and scientists in any discipline from locations around the world will have access to it to perform research."

This past summer Gilbert, Nowack, and undergraduate students in Purdue's Department of Earth and Atmospheric Sciences Dane Dudley and Austin McGlannan performed reconnaissance to determine the best sites for seismic stations in Indiana and parts of northern Kentucky.

Dudley and McGlannan used geographic databases to identify optimal locations for seismic sensors. The team then visited the sites to inquire if landowners would be willing to host seismometers on their property and to verify that the locations were appropriate for a seismic station.

It is important that a site be free of local seismic noise, such as nearby rivers and road traffic, or exposure to too much wind, that can reduce the quality of the data recorded.

Each site also needs to have a strong wireless phone signal so that the seismic instrument can transmit data with good fidelity, Gilbert said.

At each location, a seismometer that measures north-south, east-west, and vertical movement is buried in a vault about six feet below the surface. Solar panels mounted on an eight-foot pole provide power.

Data is recorded continuously and is relayed in real-time via cell phone modems to the USArray operations center in California.

A permanent seismic station was previously set up on Purdue Research Foundation property about seven miles west of the West Lafayette campus. The station is part of a permanent backbone network of seismic stations that will provide a long-term data reference for comparison of observations made by the USArray.

Visualizations from the USArray network

]]> Tue, 21 FEB 2012 08:57:55 AEST Paris (AFP) Oct 24, 2011 - The 7.2-magnitude earthquake that struck Van province in eastern Turkey on Sunday, causing hundreds of fatalities, underscores the country's fate to be straddling one of the world's most active seismic zones.

Turkey is squeezed between two tectonic plates -- Eurasia to the north and Africa/Arabia to the south -- that are grinding into each other, according France's Paris Institute of the Physics of the Globe (IPGP).

Sunday's quake occurred on the East Anatolian Fault where an arrow-shaped plate, comprising the Arabian peninsula, part of southeastern Turkey and Iraq, is forcing its way under the Eurasian plate at an average speed of 2.4 centimetres (one inch) per year.

This same fault was to blame for the Spitak quake in Armenia in 1988, when more than 20,000 people were killed by a 6.9-magnitude event.

In 1976, several villages on the Turkish-Iranian border were wiped out by a 7.3-magnitude quake that occurred around 70 kilometres (44 miles) from Sunday's quake.

Turkey's other big seismic front is the North Anatolian Fault, where several quakes occurred last century along almost its entire length.

A 7.8-magnitude quake at Erzincan in 1939 claimed nearly 33,000 lives, and the 1999 Izmit quake, estimated at 7.6 to 7.7 magnitude, left a toll of 17,000 dead and 50,000 injured, while around half a million people were left homeless.

]]> Tue, 21 FEB 2012 08:57:55 AEST Providence RI (SPX) Oct 11, 2011 - Rifting is one of the fundamental geological forces that have shaped our planet. Were it not for the stretching of continents and the oceans that filled those newly created basins, Earth would be a far different place. Yet because rifting involves areas deep below the Earth's surface, scientists have been unable to understand fully how it occurs.

What is known is that with rifting, the center of the action lies in the lithosphere, which makes up the tectonic plates and includes the crust and part of the upper mantle.

In a paper in Science, researchers at Brown University produce the highest-resolution picture of the bottom of the lithosphere in southern California, one of the most complex, captivating geologic regions in the world. The team found the lithosphere's thickness differs markedly throughout the region, yielding new insights into how rifting shaped the southern California terrain.

"What we're getting at is how (continental) plates break apart," said Vedran Lekic, a postdoctoral researcher at Brown University and first author on the paper. "What happens below the surface is just not known."

The team measured the boundary separating the lithosphere from the more ductile layer just below it known as the asthenosphere in a 400-by-300-mile grid, an area that includes Santa Barbara, Los Angeles, San Diego and the Salton Trough. The lithosphere's thickness varies surprisingly from less than 25 miles to nearly 60 miles, the researchers write.

"We see these really dramatic changes in lithosphere thickness, and these occur over very small horizontal distances," said Karen Fischer, professor of geological sciences at Brown and a paper author. "That means that the deep part of the lithosphere, the mantle part, has to be strong enough to maintain relatively steep sides."

"This approach provides a new way to put observational constraints on how strong the rocks are at these depths," she added.

Specifically, the researchers found two areas of particular interest. One is the Western Transverse Range Block. The plate lies below Santa Barbara, yet some 18 million years ago, it was located some 125 miles to the south and hugged the coastline. At some point, this plate swung clockwise, rotating more than 90 degrees and journeyed northward, like a mobile, swinging door.

Interestingly, the lithosphere remained intact, while the area left behind the swinging plate, called the Inner Continental Borderland and which lies off the coast of Los Angeles, was stretched, the Brown geophysicists believe. Indeed, the lithosphere is nearly 30 percent thinner in the area left behind than the range block.

"The fact that the Western Tranverse Range Block retained its lithosphere along its journey tells us the mantle-lithosphere (of the block) must be very strong," Lekic said.

Another interesting feature noted by the researchers is the Salton Trough, which encompasses the Salton Sea and the city of Palm Springs, and "is a classic example of rifting," according to Fischer.

Some 6 million years ago, the continental plate at this location was stretched, but the question remains whether it simply thinned or whether it actually broke apart, creating new lithosphere in between. In the paper, the researchers confirm that the lithosphere is thin, but "we can't tell which of these scenarios happened," Fischer said.

However, the thickness of the mantle part of the lithosphere and the fact that deformation at the surface runs all the way to the base of the lithosphere in roughly the same geographical location are new constraints against which modelers can test their predictions, she added.

The team made use of permanent seismic recording stations set up by the Southern California Seismic Network and other networks, as well as seismometers from the EarthScope USarray Transportable Array, a grid of National Science Foundation-funded stations that is gathering earthquake information as it moves west to east across the nation.

To measure the lithosphere's depth, the authors looked at how waves generated by earthquakes - called S waves and P waves - convert from type S to type P across the boundary between the lithosphere and the asthenosphere.

The team will compare its results with those of another famous rift system in East Africa, from a study at the University of Bristol led by Kate Rychert, who earned her doctorate at Brown in 2007.

Scott French, who earned his baccalaureate at Brown and is now a doctoral student at Berkeley Seismological Laboratory in California, is an author on the paper. The National Science Foundation funded the study, through its Earthscope program and an Earth Sciences postdoctoral fellowship to Lekic.

]]> Tue, 21 FEB 2012 08:57:55 AEST Subscribe to our daily selection of space, military, environment and energy newsletters responseText http://visitor.constantcontact.com/manage/optin/ea?v=0016gbbKsaiGSpQFojVO8ZoHw%3D%3D