Advancing the state-of-the-art in seismic science

September 30, 2014

LLNL seismologist Artie Rodgers in Brushy Peak Regional Preserve near the Greenville fault in Livermore. In light of the Aug. 24 South Napa earthquake, Rodgers suggests the Livermore area would benefit from an expanded early warning system. Credit: Bob Sickles/LLNL

Data received from seismic monitoring stations coupled with information rapidly shared via smartphones and the Internet by those who experienced the south Napa temblor is serving to advance scientists’ understanding of earthquakes as well as improving rapid response, according to Artie Rodgers of the Lab’s Seismology Group and Geophysical Monitoring Program.

Rodgers recently provided a summary of what has been learned so far from the event in a presentation entitled, “The Aug. 24 South Napa Earthquake: What Is Known So Far, Accessing Open Information and Preliminary Ground Motion Simulations.”

The 6.0 magnitude earthquake that ruptured a 12-kilometer stretch of the West Napa Fault at 3:20 a.m. on Aug. 24 was the largest “event” in the Bay Area since the Loma Prieta earthquake of October 1989. So far, one fatality and 100 injuries and more than $100 million in damage has resulted from the Napa quake.

“This event tested real-time monitoring and rapid response,” Rodgers said. “The Napa quake was large enough to cause widespread damage, especially to unreinforced masonry buildings; but nowhere near the devastation that would be expected from a magnitude 7 quake along the Hayward, Rodgers Creek or San Andreas faults.”

A new source of data for seismic researchers is information received from people who sent out messages using their smartphones or using the Internet in the minutes following the quake. “Crowd sourcing and apps for smartphones offer new ways to understand the impact of quakes in specific areas and that’s really exciting,” Rodgers said. “There’s so much data out there that we can take advantage of.” Emergency responders used this information to rapidly identify areas to search for damage while researchers sought evidence of the earthquake rupture and deployed instruments.

The United States Geological Survey (USGS) collects information on a website called “Did You Feel It?” The idea, according to the website, is to “tap the abundant information available about earthquakes from the people who actually experience them” in near real time. Information provided contributes to the scientific body of information about the effects of an earthquake. USGS provides a number of open information resources about earthquakes on its Web pages.

The Napa event served to underscore that “engineering, building design and construction practices really matter,” Rodgers said.

By way of example, he compared the damage from the Napa event with the Aug. 3 magnitude 6.1 Ludian shaker in Yunnan, China, where 619 people died and 25,800 homes were destroyed. There was one fatality in Napa and far fewer homes were lost.

This is of particular importance in the San Francisco Bay Area where, the USGS and others believe, there is a 63 percent chance for one or more magnitude 6.7 or greater earthquakes between 2007 and 2036, with the Hayward and Rodgers Creek faults being the most likely locations.

The Napa event also served as a test for the Earthquake Early Warning (EEW) system. An earthquake fault rupture sends out different types of motion waves with fast moving P-waves arriving first, followed by the slower but more damaging S-waves and later surface waves, Rodgers explained. Sensors detect the P-waves and transmit data to an earthquake alert center where the location and size of the event are determined and updated as more data becomes available. The alert center then sends out warnings before damaging S- and surface waves arrive.

Rodgers said that the first P-waves detected and transmitted by sensors in Napa provided the alert center in Berkeley with five seconds advance notice. “Five seconds may not sound like much,” he said. “But it can be enough time to shelter or to exit a building.”

“The early warning worked well for the South Napa earthquake,” Rodgers said. “Improvements to the seismic sensor network will make the early warning system even better.”

Recalling the 5.8 magnitude Livermore earthquake along the Greenville Fault in 1980 that caused $10 million in damage, Rodgers suggested the local area would benefit from an expanded early warning system.

Early warnings also could be improved by tapping data from ubiquitous mobile phones, and the Berkeley Seismological Laboratory has even developed a “MyQuake” app.

Earthquake data is collected in a variety of ways including: GPS stations, which observe very precise pointwise geodetic displacements; satellites using interferometric synthetic aperture radar (InSAR); and radar systems carried aboard airplanes allow a timely and detailed view of major events.

The vast quantities of data collected from the Napa quake also help determine details of the rupture and to validate and hopefully refine the three-dimensional (3D) subsurface structure using simulations run on LLNL High Performance Computing (HPC) systems. Seismic simulations allow scientists to better understand the distribution of shaking and damage that can accompany earthquakes, including possible future-scenario earthquakes.

Lawrence Livermore’s Anders Petersson and Bjorn Sjogreen have developed the Seismic Wave 4th order (SW4) code, which is enabling some of the most detailed, and realistic seismic simulations yet conducted. They’ve run simulations on the Vulcan supercomputer evaluating different scenarios on the 70-mile long, 9-mile deep Hayward Fault, evaluating the “intensity” of shaking.

Intensity, measured using the Modified Mercalli Intensity scale, is a qualitative way to measure the strength of ground shaking at a particular location. Typically, intensity is greatest near the earthquake epicenter. It should not be confused with “magnitude,” measured by a seismograph using the Richter scale, which relates to the energy released by an earthquake.

Coincidentally, Petersson presented his latest work on SW4 in a seminar just three days before the Napa earthquake struck. The complexity of surface and subsurface earth features, particularly almost incompressible materials such as clay, make accurately modeling wave propagation a challenge, he told scientists in attendance.

Rodgers has used the recent event data collected from Napa to run simulations on the Lab’s Cab supercomputer, a 430-teraflop Intel system, notably modeling observed broadband earthquake waves that cause damage to manmade structures. While models need further refinement, he said the Napa earthquake “provided validation data to evaluate current capabilities for ground motion predictions.”

Studying the effects of earthquakes on manmade structures, particularly in a place as urbanized as the Bay Area, allows people to better prepare for the next one. “We can’t stop earthquakes,” Rodgers said. “But we can certainly make our experience of them safer.”

Note : The above story is based on materials provided by Lawrence Livermore National Laboratory

Researchers Reveal New Rock Formation in Colorado

September 29, 2014

Hand sample of Tava sandstone from Figure 2 of Siddoway and Gehrels.

Boulder, Colo., USA – An astonishing new rock formation has been revealed in the Colorado Rockies, and it exists in a deeply perplexing relationship with older rocks. Named the Tava sandstone, this sedimentary rock forms intrusions within the ancient granites and gneisses that form the backbone of the Colorado Front Range. The relationship is fascinating because it is backward: ordinarily, it is igneous rocks such as granite that would that intrude into sedimentary rocks

Tectonostratigrahpic diagram of the Colorado Front Range; from Figure 3 of Siddoway and Gehrels.

According to authors Christine Smith Siddoway and George E. Gehrels, to find sandstone injected into granite is utterly uncommon — the extensive system that is found in Colorado may be unique in the world. There is evidence that the process of formation involved very large earthquakes, or possibly another type of catastrophic event, causing liquefaction of sediment, what they call “‘natural fracking’ in a certain sense!” Equally astonishing is the time of formation of the Tava sandstone, determined from detrital zircon analysis: the Tava proves to be from a time period ~750 million years ago, which was not known to be represented in the Colorado Rockies: the Cryogenian Period.

FEATURED ARTICLE
Basement-hosted sandstone injectites of Colorado: A vestige of the Neoproterozoic revealed through detrital zircon provenance analysis
Christine Smith Siddoway, Dept. of Geology, The Colorado College, Colorado Springs, Colorado 80903, USA; and George E. Gehrels Dept. of Geosciences, University of Arizona, Tucson, Arizona 85712, USA. Published online ahead of print on 22 Aug. 2014; http://dx.doi.org/10.1130/L390.1

Note : The above story is based on materials provided by The Geological Society of America, Inc.

New geologic map of Mars, storm surge in Florida

September 29, 2014

This is a geologic map of Mars. Colors show distribution of 44 map units (Robinson projection, Mars Orbiter Laser Altimeter (MOLA) shaded-relief background). For example, greens represent mainly lowland and basin units; yellow is relatively young impact material; reds and purples are volcanic units; blues are polar units; and earth tones are apron, transition, and highland units. Credit: Adapted from Tanaka et al. [2014]

Table of Contents

From this week’s Eos: The New Geologic Map of Mars: Guiding Research and Education

Currently, five spacecraft are investigating Mars, and a swarm of new missions to the Red Planet either have been launched or are in development. They are designed to probe the surface, subsurface, and atmosphere with a host of scientific instruments. Where will they make new discoveries? Clues to where they should focus investigations can be gleaned from the planet’s new geologic map.

From AGU’s journals: History of storm surge in Florida strongly underestimated

The observational hurricane record for northwestern Florida is just 160 years long, yet hurricane activity is known to vary strongly over thousands of years. Digging back into the prehistorical hurricane record, Lin et al. find that scientists’ reliance on such a narrow slice of observations has led them to sorely underestimate the frequency with which large hurricanes have slammed into Florida’s Gulf Coast.

Based on historical records, northwestern Florida gets hit by a hurricane packing a five-meter (16-foot) storm surge every 400 years. Incorporating long-term paleohurricane records, the authors find that the frequency of such a storm is actually closer to every 40 years.

When strong storms batter the shore, waves can carry sediment far inland. Digging down into the sediment record, researchers can reproduce the occurrence of past storm surge. Using a hurricane model and storm surge sediment observations, the authors calculated the intensity and frequency of past hurricanes in Florida’s Apalachee Bay. They find that while the frequency of hurricanes hitting the Gulf Coast has remained relatively the same over the past few thousand years, the storms’ average intensities have been, at times, much higher than during the past 160 years.

Based on their paleohurricane storm surge observations, the authors suggest that, historically, northwestern Florida would see a storm surge of 6.3 meters (20.7 feet) every 100 years, 8.3 meters (27.2 feet) every 500 years, and 11.3 meters (37.1 feet) in a worst case scenario event. A storm surge of eight meters (26 feet), they say, would push tens of kilometers inland.

The authors suggest that assessments of hurricane risk in other coastal regions may also be biased by relatively short observational records, though the direction and magnitude of that bias is not obvious.

Note : The above story is based on materials provided by American Geophysical Union

Suomi NPP Satellite Data Used for Mitigating Aviation Related Volcanic Hazards

September 29, 2014

The MODIS instrument aboard NASA’s Terra satellite captured this view of the eruption Iceland’s Bárdarbunga Volcano on Sept. 5, 2014. The red outline indicates heat. A plume of gas and steam is blowing east. Image Credit: Jeff Schmaltz/NASA MODIS Rapid Response

A joint NOAA/NASA satellite is one of several satellites providing valuable information to aviators about volcanic hazards. An aviation “orange” alert was posted on August 18, 2014, for Bárðarbunga, a stratovolcano located under the Vatnajökull glacier in Iceland, indicating the “volcano shows heightened or escalating unrest with increased potential of eruption.”

Much of the information leading to that alert came from satellites including Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on board the National Oceanic and Atmospheric Administration (NOAA)/NASA Suomi National Polar-orbiting Partnership (Suomi NPP).

While the Vatnajökull ice cap and its seismic activity has been gradually increasing over the past seven years, these recent events in Iceland are reminiscent of the destructive aftermath from the 2010 eruption of the Eyjafjallajökull volcano in Iceland. The Eyjafjallajökull eruption caused a six-day travel ban over the controlled airspace of many European countries. Data from NOAA satellites were used in the volcanic ash detection and property retrieval algorithm to create products to be used by the Volcanic Ash Advisory Centers (VAAC), including the London VAAC. The data given to the air traffic control organizations provided the information they needed to make the decision to divert and ground more than 4,000 flights. The ban was in effect to address the possibility of volcanic ash ejection causing damage to aircraft engines and risking human life. This was the largest air-traffic shut down since World War II, costing $1.7 billion in losses for the airline industry, as well as innumerable losses within freight imports and exports; tourism industries and the access to fresh food and essential goods.

Ash trajectories over Iceland on May 6, 2010, created by the Center for Satellite Applications and Research (STAR). Image Credit: STAR

Recently, Mike Pavolonis, is a NOAA scientist from the Center for Satellite Applications and Research (STAR) presented his work on How Weather Satellites are Mitigating Aviation-related Volcanic Hazards during a NOAA event. “Only 10 percent of the world’s volcanoes are routinely monitored from the ground, making satellites the only frequently available tool that can reliably identify volcanic eruptions anywhere in the world,” Pavolonis said. Advanced analysis of data from polar orbiting and geostationary satellites reduces the probability of a disastrous and/or costly aircraft encounter with volcanic ash and helps to minimize the cost associated with avoiding volcanic ash.

NOAA operates two of the nine Volcanic Ash Advisory Centers – the Anchorage Alaska VACC and the Washington VAAC – that provide operational support to the aviation sector to warn about these hazards for over a decade. He highlighted how volcanic ash can severely impact air travel, melting in a plane engine’s combustion chamber and even shutting the engine down completely. This occurred in June 1982, when a British Airways B747 aircraft flew into a volcanic ash cloud from Mount Galunggung (Indonesia) and lost power in all four engines. They dropped from 37,000 feet to 12,000 feet before three engines were restarted and the plane was able to make an emergency landing in Jakarta, Indonesia.

The pilots were unable to see the ash on their radar. Thick, billowing ash clouds from volcanoes often spread out over large areas—well beyond the erupting volcano. Aircraft close calls with volcanic ash have continued over the years. In 2011, U.S. Secretary of State, Hillary Clinton had to cut short a three-nation tour of Africa following a volcano eruption that created an ash cloud over parts of East Africa. These high profile events motivate the work to provide volcanic ash warnings as early as possible after an eruption.

The STAR volcanic ash algorithm takes data from satellites to create actionable information that can assist in advanced warning of volcanic eruptions and ash detection. The addition of the VIIRS instrument aboard the NOAA/NASA Suomi NPP satellite to the STAR volcanic cloud analysis system, has proven to be vital for detecting and characterizing small scale thermal signatures and clouds associated with volcanic activity. These thermal signals can be a precursor to an explosive eruption.

The VIIRS instrument is suited to detect the relatively unique spectral signature difference of volcanic clouds often absorb and reflect radiation as a function of wavelength in a manner that is very different from other cloud types. Future plans include incorporating information from Suomi NPP’s Cross-track Infrared Sounder and the Ozone Mapping and Profiler Suite instruments into the algorithm.

NOAA’s polar satellites are critical for a variety of “nowcasting” capabilities in addition to volcanic ash including imagery to monitor storms, fog, sea ice, and other dangerous weather and environmental conditions as well as providing data for more accurate weather forecasting to secure a more ‘Weather-Ready Nation’ thereby saving lives and protecting property.

For more information and statistic about volcanic ash detection, visit: http://www.star.nesdis.noaa.gov/goesr/product_aero_vol.php

For more information about the Suomi NPP satellite, visit: www.nasa.gov/NPP or http://www.nesdis.noaa.gov/npp_launch.html

Note : The above story is based on materials provided by NASA’s Goddard Space Flight Center

Innovative Stone Age tools were not African invention, say researchers

September 29, 2014

This image shows Levallois and biface tools. Credit: Royal Holloway, University of London

A new discovery of thousands of Stone Age tools has provided a major insight into human innovation 325,000 years ago and how early technological developments spread across the world, according to research published in the journal Science.

Researchers from Royal Holloway, University of London, together with an international team from across the United States and Europe, have found evidence which challenges the belief that a type of technology known as Levallois – where the flakes and blades of stones were used to make useful products such as hunting weapons – was invented in Africa and then spread to other continents as the human population expanded.

They discovered at an archaeological site in Armenia that these types of tools already existed there between 325,000 and 335,000 years ago, suggesting that local populations developed them out of a more basic type of technology, known as biface, which was also found at the site.

Dr Simon Blockley and Dr Alison MacLeod, from the Department of Geography at Royal Holloway, analysed volcanic material that preserved the archaeological site in the village of Nor Geghi, in the Kotayk Province of Armenia. By employing innovative procedures developed at Royal Holloway, they extracted suitable material to help date the Levallois tools.

“The discovery of thousands of stone artefacts preserved at this unique site provides a major new insight into how Stone Age tools developed during a period of profound human behavioural and biological change”, said Dr Blockley. “The people who lived there 325,000 years ago were much more innovative than previously thought, using a combination of two different technologies to make tools that were extremely important for the mobile hunter-gatherers of the time.

“Our findings challenge the theory held by many archaeologists that Levallois technology was invented in Africa and spread to Eurasia as the human population expanded. Due to our ability to accurately date the site in Armenia, we now have the first clear evidence that this significant development in human innovation occurred independently within different populations.”

Archaeologists argue that Levallois technology was a more innovative way of crafting tools, as the flakes produced during the shaping of the stone were not treated as waste but were made at predetermined shapes and sizes and used to make products that were small and easy to carry. With the more primitive biface technology, a mass of stone was shaped through the removal of flakes from two surfaces in order to produce bigger tools such as a hand axes.

Note : The above story is based on materials provided by Royal Holloway, University of London

Star Trekish, rafting scientists make bold discovery on Fraser River

September 29, 2014

This is among the almost 40 canyons through which SFU researcher Jeremy Venditti led a rafting expedition to study river flow in the Fraser River’s bedrock canyons. © Simon Fraser University

A Simon Fraser University-led team behind a new discovery has “…had the vision to go, like Star Trek, where no one has gone before: to a steep and violent bedrock canyon, with surprising results.”

That comment comes from a reviewer about a truly groundbreaking study just published in the journal Nature.

Scientists studying river flow in bedrock canyons for the first time have discovered that previous conceptions of flow and incision in bedrock-rivers are wrong.

SFU geography professor Jeremy Venditti led the team of SFU, University of Ottawa and University of British Columbia researchers on a scientific expedition on the Fraser River.

“For the first time, we used oceanographic instruments, commonly used to measure three-dimensional river flow velocity in low land rivers, to examine flow through steep bedrock canyons,” says Venditti. “The 3-D instruments capture downstream, cross-stream and vertical flow velocity.”

To carry out their Star Trek-like expedition, the researchers put their lives into the experienced hands of Fraser River Rafting Expeditions, which took them into 42 bedrock canyons. Equipped with acoustic Doppler current profilers to measure velocity fields, they rafted 486 kilometres of the Fraser River from Quesnel to Chilliwack. Their raft navigated turbulent waters normally only accessed by thrill-seeking river rafters.

“Current models of bedrock-rivers assume flow velocity is uniform, without changes in the downstream direction. Our results show this is not the case,” says Colin Rennie, an Ottawa U civil engineering professor.

“We observed a complicated flow field in which high velocity flow plunges down the bottom of the canyon forming a velocity inversion and then rises along the canyon walls. This has important implications for canyon erosion because the plunging flow patterns result in greater flow force applied to the bed.”

The scientists conclude that river flow in bedrock canyons is far more complex than first thought and the way scientists have linked climate, bedrock incision and the uplift of mountains needs to be rethought. They say the complexity of river flow plays an important role in deciding bedrock canyon morphology and river width.

“The links between the uplift of mountain ranges, bedrock incision by rivers and climate is one of the most important open questions in science,” notes Venditti. “The incision that occurs in bedrock canyons is driven by climate because the climate system controls precipitation and the amount of water carried in rivers. River flow drives the erosional mechanisms that cut valleys and allow the uplift of majestic mountain peaks.”

Venditti adds that river flow velocity in bedrock canyons also influences the delivery of sediment from mountain-rivers to lowland rivers.

“Sediment delivery controls water levels and stability of lowland rivers, which has important implications for lowland river management, flooding impacts to infrastructure, availability of fish habitat and more.

“Lowland river floodplains and deltas are the most densely populated places on earth, so understanding what is happening in mountain rivers is important because our continued development of these areas is significantly affected by what is happening upstream.”

The Natural Sciences and Engineering Research Council funded this study.

Simon Fraser University is consistently ranked among Canada’s top comprehensive universities and is one of the top 50 universities in the world under 50 years old. With campuses in Vancouver, Burnaby and Surrey, B.C., SFU engages actively with the community in its research and teaching, delivers almost 150 programs to more than 30,000 students, and has more than 130,000 alumni in 130 countries.

Note : The above story is based on materials provided by Simon Fraser University

Strange formation on Colorado Rockies sheds light on Earth’s past

September 28, 2014

Central Colorado’s Tava sandstone (light-colored band of rock at center, with geology student for scale) probably formed between 680 million and 800 million years ago, a new study suggests. Siddoway and Gehrels, Lithosphere (2014)

In the Front Range of the Colorado Rockies, smack in the middle of a cliff that overlooks U.S. Highway 24, resides a very unusual geological formation. This reddish gray, sharp-edged, and erosion-resistant swath of sandstone stands in stark contrast to the crumbling, heavily weathered granites that lie on either side. Now, scientists say they have narrowed down when this anomaly and others like it in this region formed—a discovery that may give researchers new clues about the breakup of an ancient supercontinent hundreds of millions of years ago.

Many outcrops of the “Tava sandstone”—derived from a Native American name for Pikes Peak, a local landmark—are found along the Ute Pass fault, which runs along the Front Range near Colorado Springs. First noted by geologists more than 130 years ago, these deposits have long been recognized as strange, says Christine Siddoway, a geologist at Colorado College, Colorado Springs. Many sandstone formations show layers of some type, signs they were laid down over time in distinct episodes by wind or flowing water. But the individual grains in the Tava sandstone, which typically are bits of quartz measuring from 125 to 250 micrometers across, are well mixed, and they’re peppered with larger bits of quartz up to 3 millimeters in diameter. Once free-flowing but now firmly cemented together with an iron-bearing mineral called hematite, the sand grains were apparently injected into cracks in ancient granite—some of them as much as 6 meters wide—under high pressure. The now-solid Tava deposits apparently flowed from vast reservoirs of once-waterlogged sand, some of them containing more than 1 million cubic meters of material.

“This is a very unusual [sandstone],” says Arlo Weil, a structural geologist at Bryn Mawr College in Pennsylvania, who wasn’t involved in the new study. “It must have been formed by a very rapid, chaotic process.”

The Tava sandstone is unusual for another reason: It may be the only large-scale deposit in the world where sedimentary rocks such as sandstone have been injected into crystalline rocks such as granite, Siddoway says. Normally, molten material flows into cracks in sedimentary rocks and then solidifies, she explains.

For well over a century, geologists have debated the age of the Tava sandstone, Siddoway notes. Although the deposit obviously must be younger than the surrounding granite, which has an estimated age between 1.03 billion and 1.09 billion years, some teams have suggested that the Tava sandstone might have formed as recently as 280 million years ago. Now, analyses by Siddoway and George Gehrels, a geologist at the University of Arizona (UA) in Tucson, shed new light on when the deposits may have formed.

For their study, the researchers analyzed samples of Tava sandstone collected at six sites near Colorado Springs. First, they extracted between 100 and 125 tiny zircons—tiny bits of erosion- and chemical-resistant mineral—from each sample. Then they used uranium/lead dating to determine the age of each zircon (the time when its parent rock crystallized). Most of the zircons were between 1.33 billion and 970 million years old, and none were younger than 850 million years old, Siddoway says. Sometime after the zircons crystallized, possibly millions of years later, these bits of mineral eroded out of their parent rock and ultimately ended up being washed or blown into what is now central Colorado. So although the zircon ages provide clues to the age of the Tava sandstone, they aren’t definitive.

To help narrow the range of possible ages for the sandstone, Siddoway and Gehrels compared the age distributions of the Tava zircons with the age distributions of zircons found in other sandstone formations in Colorado, Utah, northern Arizona, and southern California. Statistically, the Tava distribution most closely matched the patterns in sandstones that had been deposited between 680 million and 800 million years ago, the researchers will report in an upcoming issue of Lithosphere.

The paper’s results are “strong, compelling evidence that this age range [for the sandstone’s deposition] is correct,” says Peter Reiners, a geophysicist at UA who was not involved in the new study.

That was an interesting era in Earth’s history, Weil says. An ancient supercontinent called Rodinia was breaking up, he notes, and what is now western North America was being stretched apart—a process that likely cracked the Colorado granites apart, creating voids that were suddenly filled with immense amounts of waterlogged sand that had accumulated atop the granites or nearby. The new findings “will change [geologists’] perspective on the Rodinia breakup,” especially regarding when the event occurred and whether it happened in several phases, he notes. They also suggest that the Ute Pass fault formed during that era, hundreds of millions of years before the Rockies were even born, making it much older than researchers have previously suspected, he adds.

If the fractures hosting the Tava sandstone were indeed formed during the breakup of Rodinia, the stretching and rifting of that supercontinent extended farther east than previously suggested, Reiners notes.

It’s not yet clear where the reservoirs of sand that flowed into the granite fractures millions of years ago were situated, Siddoway says. She and her colleagues are now trying to figure that out. But the sands “almost certainly percolated downward from the surface into the older, underlying bedrock,” Reiners says. Scientists have suggested that similar formations in Sweden formed when the immense weight of glacial ice forced sand and other loose material into fissures in underlying rocks. “These rocks are unusual and not very common, but they’re not unheard of,” he says.

Note : The above story is based on materials provided by Sid Perkins “American Association for the Advancement of Science.”

Geochemical signals foretell Icelandic earthquakes

September 28, 2014

Seismologists have long yearned for a way to forecast imminent earthquakes, which remain predictable only in a long-term probabilistic sense. Past studies have suggested that earthquake precursors could take the form of changes in electromagnetic fields, radon levels, or even animal behavior—but the evidence has been anything but rock-solid.

Now, researchers have found that, just before two large earthquakes in Iceland, geochemical signals changed dramatically in nearby ground water. Measuring ground water from a 100-meter-deep borehole, they found that hydrogen isotope ratios and sodium levels spiked in the months before the earthquake. One magnitude-5.6 earthquake occurred in October 2012 along the Húsavík-Flatey fault (pictured), and the other, a magnitude-5.5, went off in April 2013 in the Grímsey Oblique Rift.

The researchers, publishing online today in Nature Geoscience, suggest that the changes could have been caused by a subtle stress-induced expansion of the rocks in the lead-up to the earthquake. The expansion, and the microfractures associated with it, could have triggered the geochemical spikes by allowing the mixing of separate bodies of ground water with different geochemical signatures.

Note : The above story is based on materials provided by Eric Hand “American Association for the Advancement of Science.”

Underwater landslide may have doubled 2011 Japanese tsunami

September 28, 2014

Tsunami waves swept over the 10-meter harbor wall at Taro, Iwate, Japan. Were they produced by a massive undersea landslide? Hitoshi Katanoda/Polaris/Newscom

An underwater landslide the size of the Paris may have triggered the worst of the tsunami that struck Japan on 11 March 2011, a new study claims.

Most of the destruction that day was caused by a 10-meter surge that overwhelmed coastal defenses from south of Fukushima to the northern tip of Honshu island. But along a 100-km mountainous stretch called Sanriku, indented with bays and small harbors, the incoming waves rose to a monstrous 40 meters. About a quarter of the tsunami’s 18,000 victims died in those ports, yet experts have struggled to find a satisfactory explanation for the exceptional inundation that killed them.

Seismologist Kenji Satake of the University of Tokyo’s Earthquake Research Institute, one of the world’s leading authorities on tsunamis, thinks a second earthquake was responsible. This temblor, he says, occurred north of the main submarine thrust, involved a thin sliver of crust, and left no trace in the seismic record of the day.

But Stephan Grilli, an oceanographer at the University of Rhode Island, Narragansett Bay, wasn’t convinced. Movements along Earth’s faults, he says, don’t jolt the sea surface in the right way to focus a band of waves on just a hundred kilometers of coastline, as happened in 2011.

In the new study, Grilli and colleagues worked back from details of the ocean surface motion recorded by gauges along the Japanese shore on the day of the earthquake. Much as sound waves can help the ear pinpoint the source of a gunshot and whether a small pistol or a large cannon fired it, tsunami waves carry the imprint of the ocean floor disturbance that created them. The team concludes that during the earthquake a slab of sediment 20 km by 40 km and up to 2 km thick slid about 300 meters down the steep slope of Japan Trench, “acting like a piston.” Grilli’s calculations also identified where the slump must have happened: near the northern end of the 2011 rupture, 170 km from the Japan shore, and under 4.5 km of water. And when marine geologist and co-author David Tappin of the British Geological Survey compared Japanese maps from before and after the earthquake, he identified just the right kind of slump in the target area. The team’s paper is in press at Marine Geology.

The authors make a good case but are far from proving it, says Costas Synolakis, a tsunami expert at the University of Southern California in Los Angeles. Synolakis collaborated with Tappin and Grilli on previous investigations establishing that a similar slump caused the deadly 1998 tsunami off Papua New Guinea. This time, however, he worries the researchers are too fixated on details of the tsunami modeling at the expense of the big picture. “Anyone who thinks you can model the behavior of a tsunami to better than a factor of two is crazy!” he says.

A close up geophysical survey to test the evidence would settle the case one way or the other, Synolakis adds. “The key point is that 4 years on, we still don’t know anything about the mechanism” of the tsunami, he says. “The observed run-up is not compatible with anything the seismologists know about.”

Satake, however, maintains that his two-quake explanation is adequate and that the existing seafloor mapping reveals nothing.

If submarine landslides are responsible, “then it’s a game-changer,” says team member Robert Geller, a seismologist at the University of Tokyo. Geller, who has lived and worked in Tokyo for a quarter of a century, has long criticized the Japanese program of earthquake forecasting, which he says produces hazard maps of little worth based on doubtful science. If towering tsunamis can also be produced by collapses along the Japan Trench, he says, the chance of anticipating the next one is nearly impossible.

Note : The above story is based on materials provided by Roland Pease “American Association for the Advancement of Science.”

Dinosaur family tree gives fresh insight into rapid rise of birds

September 25, 2014

Researchers examined the evolutionary links between ancient birds and their closest dinosaur relatives, by analyzing the anatomical make-up of more than 850 body features in 150 extinct species, and used statistical techniques to analyze their findings and assemble a detailed family tree. Credit: Steve Brusatte

The most comprehensive family tree of meat-eating dinosaurs ever created is enabling scientists to discover key details of how birds evolved from them.

The study, published in the journal Current Biology, shows that the familiar anatomical features of birds — such as feathers, wings and wishbones — all first evolved piecemeal in their dinosaur ancestors over tens of millions of years.

However, once a fully functioning bird body shape was complete, an evolutionary explosion began, causing a rapid increase in the rate at which birds evolved. This led eventually to the thousands of avian species that we know today.

A team of researchers, led by the University of Edinburgh (UK) and including Swarthmore College Associate Professor of Statistics Steve C. Wang, examined the evolutionary links between ancient birds and their closest dinosaur relatives. They did this by analyzing the anatomical make-up of more than 850 body features in 150 extinct species and used statistical techniques to analyze their findings and assemble a detailed family tree.

Based on their findings from fossil records, researchers say the emergence of birds some 150 million years ago was a gradual process, as some dinosaurs became more bird-like over time. This makes it very difficult to draw a dividing line on the family tree between dinosaurs and birds.

Findings from the study support a controversial theory proposed in the 1940s that the emergence of new body shapes in groups of species could result in a surge in their evolution.

“The evolution of birds from their dinosaur ancestors was a landmark in the history of life,” says Wang. “This process was so gradual that if you traveled back in time to the Jurassic, you’d find that the earliest birds looked indistinguishable from many other dinosaurs.”

Wang invented a novel statistical method that was able to take advantage of new kinds of data from the fossil record, which reached the conclusion that early birds had a high rate of evolution. He adds that “birds as we know them evolved over millions of years, accumulating small shifts in shape and function of the skeleton. But once all these pieces were in place to form the archetypal bird skeleton, birds then evolved rapidly, eventually leading to the great diversity of species we know today.”

“There was no moment in time when a dinosaur became a bird, and there is no single missing link between them, ” says Steve Brusatte of the University of Edinburgh’s School of GeoSciences, who led the study. “What we think of as the classic bird skeleton was pieced together gradually over tens of millions of years. Once it came together fully, it unlocked great evolutionary potential that allowed birds to evolve at a super-charged rate.”

The work was supported by the European Commission, National Science Foundation, the University of Edinburgh, Swarthmore College’s Research Fund, Swarthmore College’s James Michener Faculty Fellowship, Columbia University, and the American Museum of Natural History.

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

Earth’s water is older than the sun

September 25, 2014

This is an illustration of water in our Solar System through time from before the Sun’s birth through the creation of the planets. Credit: Bill Saxton, NSF/AUI/NRAO

Water was crucial to the rise of life on Earth and is also important to evaluating the possibility of life on other planets. Identifying the original source of Earth’s water is key to understanding how life-fostering environments come into being and how likely they are to be found elsewhere. New work from a team including Carnegie’s Conel Alexander found that much of our Solar System’s water likely originated as ices that formed in interstellar space. Their work is published in Science.

Water is found throughout our Solar System. Not just on Earth, but on icy comets and moons, and in the shadowed basins of Mercury. Water has been found included in mineral samples from meteorites, the Moon, and Mars.

Comets and asteroids in particular, being primitive objects, provide a natural “time capsule” of the conditions during the early days of our Solar System. Their ices can tell scientists about the ice that encircled the Sun after its birth, the origin of which was an unanswered question until now.

In its youth, the Sun was surrounded by a protoplanetary disk, the so-called solar nebula, from which the planets were born. But it was unclear to researchers whether the ice in this disk originated from the Sun’s own parental interstellar molecular cloud, from which it was created, or whether this interstellar water had been destroyed and was re-formed by the chemical reactions taking place in the solar nebula.

“Why this is important? If water in the early Solar System was primarily inherited as ice from interstellar space, then it is likely that similar ices, along with the prebiotic organic matter that they contain, are abundant in most or all protoplanetary disks around forming stars,” Alexander explained. “But if the early Solar System’s water was largely the result of local chemical processing during the Sun’s birth, then it is possible that the abundance of water varies considerably in forming planetary systems, which would obviously have implications for the potential for the emergence of life elsewhere.”

In studying the history of our Solar System’s ices, the team — led by L. Ilsedore Cleeves from the University of Michigan — focused on hydrogen and its heavier isotope deuterium. Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons. The difference in masses between isotopes results in subtle differences in their behavior during chemical reactions. As a result, the ratio of hydrogen to deuterium in water molecules can tell scientists about the conditions under which the molecules formed.

For example, interstellar water-ice has a high ratio of deuterium to hydrogen because of the very low temperatures at which it forms. Until now, it was unknown how much of this deuterium enrichment was removed by chemical processing during the Sun’s birth, or how much deuterium-rich water-ice the newborn Solar System was capable of producing on its own.

So the team created models that simulated a protoplanetary disk in which all the deuterium from space ice has already been eliminated by chemical processing, and the system has to start over “from scratch” at producing ice with deuterium in it during a million-year period. They did this in order to see if the system can reach the ratios of deuterium to hydrogen that are found in meteorite samples, Earth’s ocean water, and “time capsule” comets. They found that it could not do so, which told them that at least some of the water in our own Solar System has an origin in interstellar space and pre-dates the birth of the Sun.

“Our findings show that a significant fraction of our Solar System’s water, the most-fundamental ingredient to fostering life, is older than the Sun, which indicates that abundant, organic-rich interstellar ices should probably be found in all young planetary systems,” Alexander said.

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

Could there really be such a thing as volcano season?

September 25, 2014

Some think it’s the time of the year. Credit: EPA

The Earth seems to have been smoking a lot recently. Volcanoes are currently erupting in Iceland, Hawaii, Indonesia and Mexico. Others, in the Philippines and Papua New Guinea, erupted recently but seem to have calmed down. Many of these have threatened homes and forced evacuations. But among their less-endangered spectators, these eruptions may have raised a question: Is there such a thing as a season for volcanic eruptions?

Surprisingly, this may be a possibility. While volcanoes may not have “seasons” as we know them, scientists have started to discern intriguing patterns in their activity.

Table of Contents

Eruptions caused by a shortened day

The four seasons are caused by the Earth’s axis of rotation tilting towards and away from the sun. But our planet undergoes another, less well-known change, which affects it in a more subtle way. Perhaps even volcanically.

Due to factors like the gravitational pull of the sun and moon, the speed at which the Earth rotates constantly changes. Accordingly the length of a day actually varies from year to year. The difference is only in the order of milliseconds. But new research suggests that this seemingly small perturbation could bring about significant changes on our planet – or more accurately, within it.

In February 2014, a study in the journal Terra Nova showed that, since the early 19th century, changes in the Earth’s rotation rate tended to be followed by increases in global volcanic activity. It found that, between 1830 and 2013, the longest period for which a reliable record was available, relatively large changes in rotation rate were immediately followed by an increase in the number of large volcanic eruptions. And, more than merely being correlated, the authors believe that the rotation changes might actually have triggered these large eruptions.

Altering the spin of a planet, even by a small amount, requires a huge amount of energy. It has been estimated that changes in the Earth’s rotation rate dissipate around 120,000 petajoules of energy each year – enough to power the United States for the same length of time. This energy is transferred into the Earth’s atmosphere and subsurface. And it is this second consequence that the Terra Nova authors believe could affect volcanoes.

The vast quantities of energy delivered to the subsurface by rotation changes are likely to perturb its stress field. And, since the magma which feeds volcanic eruptions resides in the Earth’s crust, stress variations there may make it easier for the liquid rock to rise to the surface, and thereby increase the rate of volcanic eruptions.

The Terra Nova study is far from conclusive. Nevertheless, the idea that minute changes to the Earth’s spin could affect volcanic motions deep within the planet is an intriguing one.

But there’s another natural phenomenon which has a much stronger claim to affect volcanic activity – one which might be just as surprising: climate change.

Eruptions caused by climate change

In recent decades, it has become apparent that the consequences of planetary ice loss might not end with rising sea levels. Evidence has been building that in the past, periods of severe loss of glaciers were followed by a significant spike in volcanic activity.

Around 19,000 years ago, glaciation was at a peak. Much of Europe and North America was under ice. Then the climate warmed, and the glaciers began to recede. The effect on the planet was generally quite favourable for humankind. But, since the mid-1970s, a number of studies have suggested that, as the ice vanished, volcanic eruptions became much more frequent. A 2009 study, for example, concluded that between 12,000 and 7,000 years ago, the global level of volcanic activity rose by up to six times. Around the same period the rate of volcanic activity in Iceland soared to at least 30 times today’s level.

There is supporting evidence from continental Europe, North America and Antarctica that volcanic activity also increased after earlier deglaciation cycles. Bizarrely, then, volcanic activity seems – at least sometimes – to rise and fall with ice levels. But why? Again, this strange effect might be down to stress.

Eruptions cause by the melting of ice

Ice sheets are heavy. Each year, Antarctica’s loses around 40 billion tonnes. They are so heavy, in fact, that as they grow, they cause the Earth’s crust to bend – like a plank of wood when placed under weight. The corollary of this is that, when an ice sheet melts, and its mass is removed, the crust springs back. This upward flexing can lead to a drop in stress in the underlying rocks, which, the theory goes, makes it easier for magma to reach the surface and feed volcanic eruptions.

The link between climate change and volcanism is still poorly understood. Many volcanoes do not seem to have been affected by it. Nor is it a particularly pressing concern today, even though we face an ice-free future. It can take thousands of years after the glaciers melt for volcanic activity to rise.

Yet while it may not be an immediate hazard, this strange effect is a reminder that our planet can respond to change in unforeseen ways. Contrary to their brutish reputation, volcanoes are helping scientists understand just how sensitive our planet can be.

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

New dinosaur from New Mexico has relatives in Alberta

September 25, 2014

This is a life restoration of Ziapelta sanjuanensis, a new species of ankylosaurid dinosaurs that was discovered in New Mexico. Credit: Sydney Mohr

A newly discovered armoured dinosaur from New Mexico has close ties to the dinosaurs of Alberta, say University of Alberta paleontologists involved in the research.

From 76 to 66 million years ago, Alberta was home to at least five species of ankylosaurid dinosaurs, the group that includes club-tailed giants like Ankylosaurus. But fewer ankylosaurids are known from the southern parts of North America. The new species, Ziapelta sanjuanensis, was discovered in 2011 in the Bisti/De-na-zin Wilderness area of New Mexico by a team from the New Mexico Museum of Natural History and Science and the State Museum of Pennsylvania.

The U of A researchers in the Faculty of Science, including recent PhD graduate Victoria Arbour and current doctoral student Michael Burns, were asked to be part of the project because of their expertise in the diversity of ankylosaurs from Alberta.

“Bob Sullivan, who discovered the specimen, showed us pictures, and we were really excited by both its familiarity and its distinctiveness — we were pretty sure right away we were dealing with a new species that was closely related to the ankylosaurs we find in Alberta,” says Arbour.

Ziapelta is described in a new paper in PLOS ONE. It stands out from other ankylosaurs because of unusually tall spikes on the cervical half ring, a structure like a yoke of bone sitting over the neck. Ziapelta’s skull also differentiates it from other known ankylosaurs.

“The horns on the back of the skull are thick and curve downwards, and the snout has a mixture of flat and bumpy scales — an unusual feature for an ankylosaurid,” notes Arbour. “There’s also a distinctive large triangular scale on the snout, where many other ankylosaurids have a hexagonal scale.”

Ziapelta hails from the Late Cretaceous, when a vast inland sea divided North America in two, and Alberta and New Mexico each boasted beachfront property. Ankylosaur fossils are common in several of the rocky formations of Southern Alberta, but none have yet been found in the lower part of an area called the Horseshoe Canyon Formation — a gap in Alberta’s ankylosaur fossil record.

“The rocks in New Mexico fill in this gap in time, and that’s where Ziapelta occurs,” says Arbour. “Could Ziapelta have lived in Alberta, in the gap where we haven’t found any ankylosaur fossils yet? It’s possible, but in recent years there has also been increasing evidence that the dinosaurs from the southern part of North America — New Mexico, Texas, and Utah, for example — are distinct from their northern neighbours in Alberta.”

Arbour says Ziapelta may have belonged to this group of southern dinosaurs — but more fossils could be waiting to be unearthed in Alberta’s Badlands. “We should be on the lookout for Ziapelta fossils in the Horseshoe Canyon Formation in the future.”

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

Drilling Into an Active Earthquake Fault in New Zealand

September 25, 2014

An aerial view of the Alpine Fault at Gaunt Creek, where the Deep Fault Drilling Project is scheduled to begin next month. Three University of Michigan geologists are participating in the $2.5 million international project, which will drill nearly a mile beneath the surface and return rock samples from an active fault known to generate major earthquakes. Credit: Photo by Ben van der Pluijm

Three University of Michigan geologists are participating in an international effort to drill nearly a mile beneath the surface of New Zealand this fall to bring back rock samples from an active fault known to generate major earthquakes.

The goal of the Deep Fault Drilling Project is to better understand earthquake processes by sampling the Alpine Fault, which is expected to trigger a large event in the coming decades.

“We’re trying to understand why some faults are more earthquake-prone than others, and that requires fundamental knowledge about the processes at work,” said Ben van der Pluijm, the Bruce R. Clark Collegiate Professor of Geology in the U-M Department of Earth and Environmental Sciences.

Van der Pluijm and two of his EES colleagues — doctoral student Austin Boles and research scientist Anja Schleicher — are part of the team scheduled to start the two-month drilling project early next month. Schleicher will spend October at the site, and Boles will be there for about six weeks starting in early November.

It will be only the second science project to drill deep into an active earthquake fault and return samples. Several years ago, scientists drilled a nearly 2-mile-deep hole into California’s San Andreas Fault. Van der Pluijm was a member of that team, as well.

“I hope we find something different this time, a different rock signature that contrasts with what we saw at the San Andreas,” he said.

The goal is to drill 0.8 miles (1.3 kilometers) into the 530-mile-long Alpine Fault, which marks the boundary between the Australian and Pacific tectonic plates, on New Zealand’s South Island. Though most of the movement along the fault is lateral rather than vertical, the fault is responsible for lifting the Southern Alps, the rugged mountain range featured in the “Lord of the Rings” movies.

Earthquakes occur on the Alpine Fault every 200 to 400 years at magnitudes of 7.5 to 8.0, with an average time between successive large earthquakes of about 330 years. Though earthquakes of that size that originate at shallow depths are capable of tremendous damage, the region is sparsely populated.

The last Alpine Fault quake occurred in 1717, and the probability of another big one occurring there in the next 50 years has been calculated at about 28 percent. So the $2.5 million Deep Fault Drilling Project presents a rare opportunity to collect and analyze samples from a major fault before it breaks.

The task for van der Pluijm and his colleagues is to analyze the possible role of clay minerals and friction melting in the fault zone. Radiometric dating, X-ray studies and isotopic-analysis techniques will be used to determine how much clay is in the rock samples and when those clays formed, as well as the likely source of the water that helped produce them.

“The information we can extract from these clays is remarkably rich,” said Boles, who will use data from the New Zealand study in his doctoral dissertation. “These clay minerals are a key tool that we can use to better understand the physical and chemical processes happening in an active fault.”

Clay minerals can help reduce friction and heat generation along a fault, lubricating it so that pressure is released through steady, relatively small and nondestructive “creeping” motions rather than the periodic violent jolts known as earthquakes.

Creeping motions were observed along the portion of the San Andreas Fault drilled by scientists several years ago. Temperatures in that fault were relatively low, and clay-rich rocks from the active zone were returned to the surface.

“We think that clays are a significant player in making faults less earthquake-prone,” van der Pluijm said. “We know that the section of the Alpine Fault we’ll be drilling has a history of producing large earthquakes. So finding little clay and, instead, evidence for frictional melting in the rock would better fit the large-earthquake scenario. That would be a fantastic breakthrough.”

In addition to sampling the fault during the two-month drilling program, researchers will install permanent pressure, temperature and seismic-monitoring sensors in the borehole.

The U-M researchers are hoping to obtain a rock sample about the volume of a baseball from deep within the Alpine Fault. That would be plenty to complete their various studies, which are funded by the National Science Foundation and the International Continental Scientific Drilling Program.

“Getting the right samples is more important than the amount,” van der Pluijm said. “Returning samples to the surface from depth is always a challenge, but I’m confident that it will work.”

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

Star Trekish, rafting scientists make bold discovery on Fraser River

September 25, 2014

SFU geographer Jeremy Venditti (orange jacket; black hat) is among several scientists aboard a Fraser River Rafting Expeditions measuring boat passing through a Fraser River canyon. Credit: SFU PAMR

A Simon Fraser University-led research team studying river flow in bedrock canyons for the first time has discovered that previous conceptions of flow and incision in bedrock-rivers are wrong.

Their study appears in the journal Nature on-line today. A Nature reviewer who recommended the journal publish the study had this to say about its ground-breaking discovery. The team ” …had the vision to go, like Star Trek, where no one has gone before: to a steep and violent bedrock canyon, with surprising results.”