Scientific drilling starts in Qaidam Basin





Joint drilling project team
Joint drilling project team

A Sino-German joint project of scientific drilling was formally launched on 31 May in the west Qaidam Basin. The work is jointly carried out by researchers from the CAS Institute of Tibetan Plateau Research (ITP), Germany’s Tuebingen University (TU), US Stanford University, and Lanzhou University. Prof. FANG Xiaomin from ITP and Prof. Erwin Appel from TU are assigned co-principal investigators of the project.



Lying in the north of the Qinghai-Tibet Plateau, the Qaidam Basin receives huge thick Cenozoic deposits up to 10,000 meters recording complete and detailed histories of uplift of the Qinghai-Tibet Plateau, basin evolution and Asian inland desertification.



This joint drilling project is planned to reach a 1,200m-deep core in the alkaline region at the local sedimentation center of the west Qaidam sub-basin. Then combining with natural outcrops nearby the deep core, it is expected to reconstruct the high resolution and precision chronologic sequence and to confirm the occurrences of seismostratigraphic boundaries.



Besides, the exploration of the deep core will also serve to reconstruct a high-resolution pattern of the history of climate change since late Miocene so as to better understand the formation and evolution of arid salt lakes as well as the relationship between such lakes and the resources of salt, oil and gas.


Moreover, it’s also aimed to reveal the interaction between the pateau uplift, climate change and soil erosion, especially the relationship between the plateau uplift and aridity-monsoon system in Asia. And new clues for the study of mineral resources such as oil, gas and sylvite are also expected to pop up, which is of much significance for the energy sustainability.



Except for following the international drilling rules, several new techniques have been applied in this project to ensure a high core-acquisition rate in the alkaline region and success in obtaining intact cores.



So far, the field team has drilled 306m deep in the salt and saliferous beds. With a core- acquisition rate up to above 95%, the drilling reveals a stratum interlaced with mudstone beds in grey black or green grey and salt beds in white. The discovery of the salt and brine deposits in the west Qaidam Basin is expected to bring forward a larger and deeper exploration of these reserves.



Co-funded by the CAS, the National Natural Science Foundation of China and the German BMBF and DFG, the project is expected to be fulfilled by the upcoming mid-October.

Undersea volcanoes triggered marine extinction, says study


Undersea volcanic activity triggered a mass extinction of marine life and buried a thick mat of organic matter on the sea floor about 93 million years ago, which became a major source of oil, according to a new study.



“It certainly caused an extinction of several species in the marine environment,” said University of Alberta Earth and Atmospheric Science researcher Steven Turgeon. “It wasn’t as big as what killed off the dinosaurs, but it was what we call an extreme event in the Earth’s history, something that doesn’t happen very often.”



U of A scientists Turgeon and Robert Creaser say the lava fountains that erupted altered the chemistry of the sea and possibly of the atmosphere.



“Of the big five mass extinctions in the Earth’s history, most of them were some kind of impact with the planet’s surface,” said Turgeon. “This one is completely Earth-bound, it’s strictly a natural phenomenon.”



Turgeon and Creaser found specific isotope levels of the element osmium, an indicator of volcanism in seawater, in black shale-rocks containing high amounts of organic matter-drilled off the coast of South America and in the mountains of central Italy.


“Because the climate was so warm back than, the oceanic current was very sluggish and it initially buffered this magmatic pulse, but eventually it all went haywire,” said Turgeon. “The oxygen was driven from the ocean and all the organic matter accumulated on the bottom of the sea bed, and now we have these nice, big, black shale deposits worldwide, source rocks for the petroleum we have today.”



According to their research, the eruptions preceded the mass extinction by a geological blink of the eye. The event occurred within 23 thousand years of the extinction and the underwater volcanic eruption had two consequences: first, nutrients were released, which allowed mass feeding and growth of plants and animals. When these organisms died, their decomposition and fall towards the sea floor caused further oxygen depletion, thereby compounding the effects of the volcanic eruption and release of clouds of carbon dioxide in to the oceans and atmosphere. The result was a global oceanic anoxic event, where the ocean is completely depleted of oxygen. Anoxic events-while extremely rare-occur in periods of very warm climate and a raise in carbon dioxide levels, which means that this research could not only help prove a mass-extinction theory, but also help scientists studying the effects of global warming.



An odd side-effect of the mass extinction, the result of the anoxic event caused as an indirect result of the underwater volcanic eruptions, was that temperatures and carbon dioxide levels on the Earth’s surface actually dropped.



“Organic matter that’s decaying returns components like carbon and CO2 to the atmosphere,” said Turgeon. “But this event locked them up at the bottom of the ocean, turning them into oil, drawing down the CO2 levels of the ocean and the atmosphere.”



After 10,000-50,000 years, the carbon dioxide levels rose again. “Business as usual,” said Turgeon, adding that this might hold a warning for organic life on the planet today, he said.



“There’s a bit of an analogy for what’s going on today,” he said. “What happens if we pump more CO2 into the atmosphere? This tells me that the oceans maybe have limited buffering capacity for CO2 .”

Earthquake Commission funds coseismic landslide research


A UC project to predict the location and volume of coseismic landslides has been awarded $30,000 funding by the Earthquake Commission (EQC).



Associate Professor Tim Davies (Geological Sciences) will develop and test a methodology for identifying the most probable source locations and volumes of earthquake-generated landslides in seismically active mountain terrain. This will be done by using available topographic and geological information that has been gathered recently by former PhD student Flo Buech.



Flo recorded earthquakes at Little Red Hill, a small, steep, rocky mountain near Lake Coleridge.



“Natural earthquakes were measured and recorded at both the bottom and the top of the mountain and it was found that at the top, the intensity of the shaking increased by a factor of up to 11, which is higher than ever recorded before and was a bit of a surprise,” Professor Davies said.



Flo attempted to reproduce this same behaviour in a 1:1000 scale model in the laboratory, “but it didn’t work very well, so the next step was to do this by computer modelling”.



With the EQC funding, PhD student Ali Bazgard will use the computer program Particle Flow Code 3D (PFC3D) to build a virtual mountain out of small spherical particles stuck together in a particular way that can be specified to make sure that they behave in the same way as a mountain.


“Then we can model the equivalent of an earthquake shaking the mountain and from that gather information. This includes measuring what parts of the mountain are most stressed to determine which shape and size will fall when shaken,” Professor Davies said.



Large amounts of rock can break up very intensely and travel large distances, he said.



“We are now in a position that if we know the amount that is going to fall and where it is going to fall from, we can predict where that debris is going to go, so we can plan ahead.



“Because of the data that we have gathered from the field we can test the model and plan where the best place is to build roads and bridges – and it might not be the most obvious place.”



Landslides as the result of an earthquake cause a lot of damage to the landscape and infrastructure. The largest landslide known in Canterbury happened 500 years ago when “500 million cubic metres fell off the back of Porter Heights skifield”.



“The next big earthquake on the Alpine Fault is overdue, so we are expecting a very large one to occur – very much like the recent Sichuan earthquake in China.”

Researcher talks about latest in Younger Dryas work in Science article





The research team in Peru at the Quelccaya Ice Cap prepares a sediment core sampler for use. - Credit: Tom Lowell
The research team in Peru at the Quelccaya Ice Cap prepares a sediment core sampler for use. – Credit: Tom Lowell

Geology researcher just back from a month at Peru’s Quelccaya Ice Cap



University of Cincinnati Professor of Geology Tom Lowell is featured in the July 18 issue of Science, discussing the latest research into the question of whether the significant climate change event about 12,900 years ago known as Younger Dryas impacted the climate all around the globe.



The Younger Dryas event refers to an unexpected rapid cooling of the earth that is known to have lasted about 1,300 years. It coincided with widespread extinctions of species, but, although the event itself is well-documented, scientists are still unclear of whether its impact was felt equally all across the globe.



The extent of the impact in the Southern Hemisphere is, in particular, unresolved.



Lowell has researched evidence of historical climate change all over the globe, including significant amounts of research south of the equator. Just this month, he has returned from a month-long expedition to Peru, where he and colleagues took samples near the Quelccaya Ice Cap.



One of the purposes of this most recent trip corresponds with the central question that Lowell has written about in Science: Why are there discrepancies in results being returned from two primary dating techniques, and what does that say about understanding Younger Dryas and other major climate change events?



“The whole point is that this was a time of rapid environmental transition that we do not understand the cause for,” says Lowell. “One of the primary things you have to understand before you can attribute cause is how widespread the event was. That’s a question my work in the Southern hemisphere has been associated with.



“It just might be that we don’t have the necessary dating techniques to make these determinations.”



Lowell is an expert in the use of radiocarbon dating techniques. His co-author in the Science piece (as well as colleague on the Peru expedition), Meredith Kelly from the Lamont-Doherty Earth Observatory, is expert in a more recently developed dating technique called surface-exposure dating, which can be obtained from boulders left behind in glacial moraines.



There are only a handful of known locations in the Southern hemisphere (one of which is Quelccaya) where samples for both kinds of testing can be obtained at the same site.


When previous sampling has been done at locations in New Zealand and Argentina, there has been conflict in the dating of the Younger Dryas event between the two techniques. Radiocarbon dating has shown that glacial advances happened prior to Younger Dryas, but surface-exposure dating indicates that glacial movement happened at the end of Younger Dryas.



That leaves scientists to ponder two likely explanations, Lowell and Kelly write in Science. The first is that the evidence being obtained through the two dating techniques are looking at two different stratified levels of samples, with the carbon-based samples likely dating back to the beginning of Younger Dryas and the advance of the glaciers and the surface-exposure samples coming from a time at the end of Younger Dryas, when the glaciers retreated.



The second option is that there could be problems in calibrating the dating techniques themselves against each other.



To test the second possibility, they undertook the recent trip to Peru.



Lowell and Kelly are also collaborating on this work with Fred Phillips, a professor of hydrology at New Mexico Tech whom Lowell describes as one of the godfathers of the surface-exposure dating process.



Also among those on the seven-member crew that made the trip to the 16,000-foot elevation in Peru were two former UC students: Colby Smith, who just finished work on his PhD in Geology, and former UC undergrad Patrick Applegate, who is now pursuing his PhD at Penn State.



Answering this question has significant implications for better understanding Younger Dryas. New work also published in this edition of Science by a team led by Robert P. Ackert from the Woods Hole Oceanographic Institution supports the conclusion that the forces causing the Younger Dryas event did not cool the eastern glaciers in the Patagonian Icefields in southern Argentina.



This finding, in conjunction with previous findings from the ice cores in Greenland and Antarctica that show that Greenland cooled during Younger Dryas while Antarctica warmed, support the theory that Younger Dryas did not have much impact farther south than the Tropics.



“We were at (Quelccaya) two years ago for preliminary work where we found evidence of this discrepancy between the two dating systems was present,” says Lowell. “This year, our effort was to obtain even more chronological data, so we could assess this problem and try to bring these techniques into compliance with each other.”



Lowell and his colleagues are aiming to make a preliminary presentation on the findings from this most recent trip in December, at the American Geophysical Union’s fall meeting in San Francisco.

Early earthquake warning: New tools show promise


Seismic ‘stress meter’ registered signs of quake 10 hours in advance



Using remarkably sensitive new instruments, seismologists have detected minute geological changes that preceded small earthquakes along California’s famed San Andreas Fault by as much as 10 hours. If follow-up tests show that the preseismic signal is pervasive, researchers say the method could form the basis of a robust early warning system for impending quakes.



The research appears this week in the journal Nature.



“We’re working with colleagues in China and Japan on follow-up studies to determine whether this physical response can be measured in other seismically active regions,” said Rice University seismologist Fenglin Niu, the study’s lead author. “Provided the effect is pervasive, we still need to learn more about the timing of the signals if we are to reliably use them to warn of impending quakes.”



Today’s state-of-the-art earthquake warning systems give only a few seconds’ warning before a quake strikes. These systems detect P-waves, the fastest moving seismic waves released during a quake. Like a flash of lightning that arrives before a clap of thunder, the fast-moving P-waves precede slower moving but more destructive waves.



Findings from the new study indicate that the stresses measured by the new instruments precede the temblor itself, so a warning system using the new technology would be fundamentally different from current warning systems.


“Detecting stress changes before an earthquake has been the Holy Grail in earthquake seismology for years and has motivated our research,” said study co-author Paul Silver of the Carnegie Institution of Science’s Department of Terrestrial Magnetism. “Researchers have been trying to precisely and continuously measure these velocity changes for decades, but it has been possible only recently, with improved technology, to obtain the necessary precision and reliability.”



In experiments near Parkfield, Calif., in late 2005 and early 2006, Niu, Silver and colleagues from Lawrence Berkeley National Laboratory (LBNL) gathered two months of measurements at the San Andreas Fault Observatory at Depth, or SAFOD, a deep well seismologists use to make direct measurements of the fault.



The team installed a high-precision seismic source made by a stack of donut-shaped piezoelectric ceramic cylinders that expand when voltage is applied — a sophisticated device akin to a stereo speaker — about one kilometer beneath the surface. At the same depth in an adjacent well, the scientists set up an accelerometer to measure the rhythmic signals from the source device.



When rocks are compressed, the stress forces air out of tiny cracks in the rock. This causes seismic waves to travel slightly faster through the rock. Niu said the variations are so slight they can be measured only with very precise instruments. For example, though the Parkfield instruments were more than a half mile below ground, the setup was sensitive enough to measure fluctuations in air pressure at the Earth’s surface.



“Scientists tried as early as the 1970s to measure changes in wave speed that are associated with the stress changes that precede seismic activity,” Niu said. “For a variety of reasons, their measurements were inconclusive. Using the precision instruments built by our collaborators at Lawrence Berkeley National Laboratory, along with new signal enhancement techniques, we were able to reach the fine level of precision required.”



In analyzing the seismic data, Niu and colleagues found that a distinct change occurred in the rock before each of the minor earthquakes near Parkfield during the test period. A measurable change preceded a magnitude 3 quake on Christmas Eve 2005 by 10 hours. This was the largest local event during the observation period. A smaller but closer magnitude 1 temblor five days later was preceded by a signal about two hours before the quake.



Additional co-authors include Rice graduate student Xin Cheng and LBNL scientists Tom Daley and Ernest Majer. The research was supported by the National Science Foundation, Rice, the Carnegie Institution and LBNL.

A Single Boulder May Prove that Antarctica and North America Were Once Connected





The Transantarctic Mountains where the boulder was found. - Credit: John Goodge / University of Minnesota-Duluth
The Transantarctic Mountains where the boulder was found. – Credit: John Goodge / University of Minnesota-Duluth

A lone granite boulder found against all odds high atop a glacier in Antarctica may provide additional key evidence to support a theory that parts of the southernmost continent once were connected to North America hundreds of millions of years ago.



Writing in the July 11 edition of the journal Science, an international team of U.S. and Australian investigators describe their findings, which were made in the Transantarctic Mountains, and their significance to the problem of piecing together what an ancient supercontinent, called Rodinia, looked like. The U.S. investigators were funded by the National Science Foundation (NSF).



Previous lines of scientific evidence led researchers to theorise that about 600-800 million years ago a portion of Rodinia broke away from what is now the southwestern United States and eventually drifted southward to become eastern Antarctica and Australia.



The team’s find, they argue, provides physical evidence that confirms the so-called southwestern United States and East Antarctica (SWEAT) hypothesis.



“What this paper does is say that we have three main new lines of evidence that basically confirm the SWEAT idea,” said John Goodge, an NSF-funded researcher with the Department of Geological Sciences at the University of Minnesota-Duluth.



Added Scott Borg, director of the division of Antarctic sciences in NSF’s Office of Polar Programs, “this is first-rate work and a fascinating example of scientists at work putting together the pieces of a much larger puzzle. Not only do the authors pull together a diverse array of data to address a long-standing question about the evolution of the Earth’s crust during a critical time for biological evolution, but the research shows how the ideas surrounding the SWEAT hypothesis have developed over time.”



As a field researcher during the late 1980’s and early 1990’s, Borg authored papers on the SWEAT hypothesis.



The boulder find came by serendipity while the researchers were picking though rubble carried through the Transantarctic Mountains by ice streams-rivers of ice-that flow at literally a glacial pace from East Antarctica.



Goodge and his team were searching for rocks that might provide keys to the composition of the underlying continent crust of Antarctica, which in most places is buried under almost two miles of ice.



“We were picking up boulders in the moraines that looked interesting,” Goodge said. “It was basically just a hodge-podge of material.”



One rock in particular, small enough to heft in one hand, found atop the Nimrod Glacier, was later determined to be a very specific form of granite with, as Goodge describes it, “a particular type of coarse-grained texture.”



Subsequent chemical and isotopic tests conducted in laboratories in the United States revealed that the boulder had a chemistry “very similar to a unique belt of igneous rocks in North America” that stretches from what is now California eastward through New Mexico to Kansas, Illinois and eventually through New Brunswick and Newfoundland in Canada.


That belt of rocks is known to have been a part of what is called Laurentia, which was a component of the supercontinent of Rodinia.



“There is a long, linear belt of these igneous rocks that stretches across Laurentia. But ‘bang’ it stops, right there at the (western) margin where we knew that something rifted away” from what is now the West Coast of the United States,” Goodge said.



“It just ends right where that ancient rift margin is,” Goodge said. “And these rocks are basically not found in any other part of the world.”



That it should turn up on a glacier high up in the mountains of Antarctica is strong evidence in support of the SWEAT model that parts of North America continue into part of the frozen continent at the bottom of the Earth.



“There’s no other explanation for how it got where we found it,” Goodge said. “It was bull-dozed over from that interior region of Antarctica.”



The find itself is compelling to geologists, Goodge noted, because little other physical evidences exists to allow them directly to put together the jigsaw puzzle of the long-disappeared Rodinia.



But because the supercontinent existed at a key time in the development of multi-cellular life on Earth, it also helps provide a geological context in which this massive biotic change took place.



“During the Cambrian explosion about 520 million years ago we started seeing this huge expansion in the diversity of life forms,” Goodge said. “This was also a time when the Earth was undergoing tremendous geologic changes.”



He added that “something helped trigger that big radiation in life.”



The shifting configuration of the continents, accompanied by collisions between landmasses, erosion and the influx of chemicals into the seas may well have provided the nutrients to that growing diversity of lifeforms.



“There are ideas developing about these connections between the geo-tectonic world on the one hand and biology on the other.



The job of geoscientists in this context, he said “is to reconstruct what the world was like at the time.”

Researchers To Fly Unmanned Planes Over Greenland Ice Sheet To Monitor Melting





Scientists hope an unmanned aircraft being flown by CU-Boulder and NOAA over Greenland this month will help them quantify how meltwater from lakes dotting the massive ice sheet is affecting glacier speed and global sea rise. Photo courtesy John Adler, CU-Boulder/NOAA
Scientists hope an unmanned aircraft being flown by CU-Boulder and NOAA over Greenland this month will help them quantify how meltwater from lakes dotting the massive ice sheet is affecting glacier speed and global sea rise. Photo courtesy John Adler, CU-Boulder/NOAA

University of Colorado and National Oceanic and Atmospheric Administration researchers hoping for a unique glimpse into the workings of the massive Greenland ice sheet are undertaking the first unmanned aerial survey of the island’s fast-flowing outlet glacier region.



This month the team is flying two small, crewless planes over a portion of the ice sheet. The goal is to understand how meltwater-fed lakes that dot the surface interact with the ice sheet’s dynamic movement and melt rate, said field campaign coordinator John Adler, a CU-Boulder doctoral student and NOAA Corps officer.



In particular, the scientists hope to learn whether the lakes can be used to predict how much water will drain from the ice sheet and contribute to sea-level rise in the future, said Adler. As the glacier moves, it forms cracks, holes and cylindrical vertical shafts in the ice known as “moulins” that allow water to rapidly drain down inside the glacier, he said.



“We want to know how much water is on top of the ice sheet, where it goes, and how much it takes to influence how fast the ice sheet slides to sea,” said Adler. Adler is studying under Professor Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences, a joint institute of CU-Boulder and NOAA.



Researchers have been closely monitoring Greenland’s climate over the past few decades, watching to see if the ice sheet is shrinking over time, said Steffen. Greenland is currently shedding about 50 cubic miles per year, he said.


“We think these marginal melt lakes are responsible for the increase in ice velocity,” said Steffen, who maintains his own research camp on the ice sheet and also directs a network of 22 stations on the ice known as the Greenland Climate Network. “They may allow water to drain to the bottom of the ice sheet and lubricate the base.”



By using Unmanned Aircraft Systems, or UAS, the researchers will be able to fly instruments at lower altitudes than would be possible with a manned plane and survey little-explored terrain without putting human life at risk, Adler said. The two planes, known as Mantas, were provided by Advanced Ceramics Research Inc. of Tucson, Ariz. Each is less than six feet long and can fit in the bed of a pickup truck.



CIRES researcher Betsy Weatherhead, one of two lead scientists for NOAA’s UAS test bed program in the Arctic, called the Greenland effort “the start of a new era of Arctic exploration.” Weatherhead said she believes the UAS will prove to be an important tool for monitoring marine mammal populations and the thinning Arctic sea ice.



“With unmanned aircraft systems, we can fly missions too dangerous, dirty or dull for humans to address questions we couldn’t even think of addressing before,” said Weatherhead.



Each Manta will carry a digital camera, atmospheric temperature and pressure sensors, an ice-surface temperature sensor and a laser range finder to allow researchers to create high-resolution digital elevation models of Greenland’s Jakobshavn glacial region, said Steffen. The planes will fly between 500 and 1,000 feet above the surface at speeds of about 45 miles per hour for up to six hours.



Each plane will carry a special camera that will collect information from across the electromagnetic spectrum to probe the depth of lakes on top of the ice sheet, said Adler. By measuring the amount of sunlight penetrating the lake water, researchers can estimate lake depth and the potential amounts of water that could drain through the ice sheet and out to sea, he said.

Tunguska catastrophe: Evidence of acid rain supports meteorite theory





In 1927 Professor Leonid Kulik took the first photographs of the massive destruction of the taiga forest after the Tunguska catastrophe. - Photo: Professor Leonid Kulik
In 1927 Professor Leonid Kulik took the first photographs of the massive destruction of the taiga forest after the Tunguska catastrophe. – Photo: Professor Leonid Kulik

The Tunguska catastrophe in 1908 evidently led to high levels of acid rain. This is the conclusion reached by Russian, Italian and German researchers based on the results of analyses of peat profiles taken from the disaster region. In peat samples corresponded to 1908 permafrost boundary they found significantly higher levels of the heavy nitrogen and carbon isotopes 15N and 13C. The highest accumulation levels were measured in the areas at the epicentre of the explosion and along the trajectory of the cosmic body. Increased concentrations of iridium and nitrogen in the relevant peat layers support the theory that the isotope effects discovered are a consequence of the Tunguska catastrophe and are partly of cosmic origin. It is estimated that around 200,000 tons of nitrogen rained down on the Tunguska region in Siberia at that time.



“Extremely high temperatures occurred as the meteorite entered the atmosphere, during which the oxygen in the atmosphere reacted with nitrogen causing a build up of nitrogen oxides,” Natalia Kolesnikova told the Russian news agency RIA Novosti on last Monday. Mrs. Kolesnolova is one of the authors of a study by Lomonosov Moscow State University, the University of Bologna and the Helmholtz Centre for Environmental Research (UFZ), which was published in the journal Icarus in 2003.



The Tunguska event is regarded as one of the biggest natural disasters of modern times. On 30 June 1908 one or more explosions took place in the area close to the Tunguska River north of Lake Baikal. The explosion(s) flattened around 80 million trees over an area of more than 2000 square kilometres. The strength of the explosion is estimated to have been equivalent to between five and 30 megatons of TNT. That is more than a thousand times as powerful as the Hiroshima bomb. This almost unpopulated region of Siberia was first studied in 1927 by Professor Leonid A. Kulik. There are a number of different theories about what caused the catastrophe. However, the majority of scientists assume that it was caused by a cosmic event, such as the impact of a meteorite, asteroid or comet.


If it had exploded in the atmosphere just under five hours later, St. Petersburg, which was the capital of Russia at that time, would have been completely destroyed because of the Earth’s rotation.



In two expeditions in 1998 and 1999, Russian and Italian researchers took peat profiles from various locations within the Siberian disaster area. The type of moss studied, Sphagnum fuscum, is very common in the peat material and obtains its mineral nutrients exclusively from atmospheric aerosols, which means that it can store terrestrial and extraterrestrial dust. Afterwards, the samples were analysed in laboratories at the University of Bologna and the Helmholtz Centre for Environmental Research (UFZ) in Halle/Saale.



Among other things, the UFZ specialises in isotope analyses of sediments, plants, soil and water and it was asked to help by the team of Moscow researchers led by Dr Evgeniy M. Kolesnikov. Kolesnikov, who has been investigating the Tunguska event for 20 years, has been to Leipzig University and UFZ twice as a guest researcher with the help of the German Research Foundation (DFG) to consult with the isotope experts. “The levels of accumulation of the heavy carbon isotope 13C measured right on the 1908 permafrost boundary in several peat profiles from the disaster area cannot be explained by any terrestrial process. This suggests that the Tunguska catastrophe had a cosmic explanation and that we have found evidence of this material,” explains Dr Tatjana Böttger of the UFZ. Possible causes would be a C-type asteroid like 253 Mathilde, or a comet like Borelly.

Icelandic Volcanoes Help Researchers Understand Potential Effects Of Eruptions





Volcanic eruptions from the volcano Askja created the small crater Víti (foreground) and large lakes, such as Öskjuvatn (background)
Volcanic eruptions from the volcano Askja created the small crater Víti (foreground) and large lakes, such as Öskjuvatn (background)

For the first time, researchers have taken a detailed look at what lies beneath all of Iceland’s volcanoes – and found a world far more complex than they ever imagined.



They mapped an elaborate maze of magma chambers – work that could one day help scientists better understand how earthquakes and volcanic eruptions occur in Iceland and elsewhere in the world.



Knowing where magma chambers are located is a key first step to understanding the chemical composition of the molten rock that is flowing within them – and of the gases that are released when a volcano erupts, explained Daniel Kelley, doctoral student in earth sciences at Ohio State University.



Kelley and Michael Barton, professor of earth sciences at Ohio State, have determined that the volcanoes in Iceland are likely to have explosive eruptions that shoot debris far into the atmosphere. That’s because the magma moves very quickly to the surface from deep within the magma chambers. Fast-moving magma propels sulfur and ash out of a volcano and high into the atmosphere, where it can spread around the planet.



“One of the reasons we’re trying to understand these volcanoes is to determine exactly what the chances are of a large eruption there. We know that a large eruption in Iceland would not only have devastating local effects, but potential global effects as well – by affecting the climate,” Barton said.



Previous eruptions in Iceland and elsewhere have released gas into the atmosphere that had global affects. An eruption of a volcano in modern-day Indonesia in 1816 led to the “year without a summer.” The explosive eruption forced sulfur and ash high into atmosphere, blocking the sun for several months and leading to global crop failure, famine, and a death toll in the thousands. Similar effects were also recorded after an eruption in Iceland in 1783.



This new study was based on the analyses of basaltic glasses — volcanic rocks created when magma from deep within the Earth is cooled very quickly at the surface and becomes glass-like. The researchers traced the origin of basaltic glass rocks gathered from the surface of Iceland to magma chambers under 28 different volcanoes, by analyzing the composition of the rocks and calculating the pressures at which the glasses were formed.



In addition to his own field work, Kelley compiled published reports of more than 500 basaltic glasses analyzed by other researchers from every volcanic center in Iceland. The study, which is the first of its kind to look at all of Iceland’s volcanoes, was published in Journal of Petrology.



Rather than using conventional methods, Kelley and Barton focused on a more unusual way to study Iceland.



“Most of the studies looking for magma chambers are done using seismic or satellite data to infer where a magma chamber might be. But by analyzing the glass, you have something that directly represents the liquid magma beneath the surface and gives you the exact location of the magma chamber,” Kelley said.





Formed by an eruption from Askja in 1875, Lake Öskjuvatn is the deepest lake in Iceland at 735 feet (224 meters).
Formed by an eruption from Askja in 1875, Lake Öskjuvatn is the deepest lake in Iceland at 735 feet (224 meters).

This new research strongly supports the idea that the middle and lower layers are actually hotter than ever imagined, up to 400 degrees Celsius (more than 750 degrees Fahrenheit) higher at the base of the crust. And with stacked chambers ranging from 1 to 35 kilometers (1 to 21 miles) below the surface, many volcanoes lie above large bases of molten rock.



At the base of the crust beneath every volcano, researchers also found complex groupings of magma chambers. Magma is constantly flowing through the chambers or injected into cracks in the crust, resulting in increased volcanic activity.



Over thousands of years, that increased volcanic activity has created a lot of basaltic glass, giving scientists clues at how magma chambers have changed over time and where eruptions have taken place in the past, Kelley said.



Knowing the sizes and locations of magma chambers past and present, scientists can better understand the events that happen shortly before and after a volcanic eruption. Previous research has suggested that earthquakes and volcanic eruptions follow one another, giving scientists a possible warning of an eruption.



“There’s a lot of magma moving inside reservoirs underneath volcanoes as they fill, the crust around them becomes deformed and that tends to generate the earthquakes. And so one of the ways you are able to predict an eruption is by looking at the seismic data,” Barton said.



Iceland is the perfect place for scientists such as Kelley and Barton to study the placement of magma chambers.



It’s a land of contrasts: glaciers blanket portions of Iceland, while pools of magma flow beneath the surface. The entire island country sits atop the Mid-Atlantic Ridge, a giant crack in the earth’s crust. The ridge separates the North American and Eurasian tectonic plates and exposes the inside of the Earth.



Almost all mid-ocean ridges lie deep under water, but Iceland is the only land-based location in the world where researchers can take this kind of first-hand look into Earth’s interior.



“A great deal of volcanic activity is centered around mid-ocean ridges, but they are almost all underwater, so we can usually only study them from ocean dredging and drilling. Iceland is the only place in the world where we can put our feet right on a mid-ocean ridge and study it,” Kelley said.



Over the next few months, Kelley plans to collect more glasses from Iceland personally. Focusing on the Askja volcano in the country’s central highlands, Kelley hopes to determine how the volcanic system has evolved over time. This new focus will add another dimension to how scientists interpret the changes in volcanic systems, he said.

A stress meter for fault zones





Seismic waves were generated in the pilot hole of the San Andreas Fault Observatory at Depth, near Parkfield, Calif., and detected in the main hole, at depths of approximately one kilometer. An inverse correlation was found between changes in wave travel time and barometric pressure, causing increased stress in the rock. - Credit: NSF
Seismic waves were generated in the pilot hole of the San Andreas Fault Observatory at Depth, near Parkfield, Calif., and detected in the main hole, at depths of approximately one kilometer. An inverse correlation was found between changes in wave travel time and barometric pressure, causing increased stress in the rock. – Credit: NSF

The speed of seismic waves is a measure of stress in rocks during — and possibly before — earthquakes



For the first time, scientists from Rice University, the Carnegie Institution of Washington, and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have measured – in the field rather than in the laboratory – how changes in stress in rocks affect changes in the speed of seismic waves at depths where earthquakes begin. The measurements could lead to a “stress meter” for better understanding how fault-zone stress is related to earthquakes.



“The goal of our project was to develop a method for measuring stress changes, especially at depths where earthquakes originate,” says Fenglin Niu of Rice University’s Department of Earth Science. “We call it a seismic stress meter.”



Niu is first author of the article reporting the research results, which appears in the 10 July issue of the journal Nature. Paul Silver of the Carnegie Institution of Washington’s Department of Terrestrial Magnetism coordinated the project, and Tom Daley and Ernest Majer of Berkeley Lab’s Earth Sciences Division provided the precision instruments which generated and detected the seismic waves.



“Over many years at Parkfield and other sites, Ernie Majer and I worked together to develop a suite of high-precision instruments for field work,” says Daley. “One of our goals was to see if our existing cross-well instrumentation would have the sensitivity to measure the pressure changes and associated travel-time changes needed for this experiment.”



The research team used the twin boreholes (“wells”) of the National Science Foundation’s San Andreas Fault Observatory at Depth (SAFOD) near Parkfield, CA, to send signals from a source one kilometer deep in the pilot hole to a receiver at the same depth in the main hole. At that depth the two SAFOD boreholes are separated by only about five meters, and any change in travel time between them is measured in microseconds.



“The source is a stack of donut-shaped piezoelectric ceramic cylinders that expand when voltage is applied,” Daley explains. “The source is suspended in the water that fills the hole, and when it expands it exerts pressure on the water, which exerts pressure on the rock; the seismic wave travels through the rock to the detector, which is in contact with the sides of the main bore hole and measures movement with accelerometers.”





Time delay of seismic waves was normally correlated with changes in stress due to barometric pressure (above). Two seismic events, one of magnitude 3 and another of magnitude 1, caused excursions from this relationship. The excursions were detected before the events occurred (arrows), possibly because of preseismic changes in the crack structure of the rock. - Credit: Niu et al
Time delay of seismic waves was normally correlated with changes in stress due to barometric pressure (above). Two seismic events, one of magnitude 3 and another of magnitude 1, caused excursions from this relationship. The excursions were detected before the events occurred (arrows), possibly because of preseismic changes in the crack structure of the rock. – Credit: Niu et al

The instruments were sensitive enough to detect changes in rock stress a kilometer deep, caused only by changes in the barometric pressure of the atmosphere – a mere change in the weight of the air on the surface.



“To get the required sensitivity we did ‘signal stacking,'” Daley says. “The source fires about four times a second, and we averaged every 45 minutes of data, to suppress random noise and to improve the signal-to-noise ratio. We collected this data continuously over two separate month-long periods.”



During the first month of data collection the team found a consistent relationship between barometric pressure and minute changes in the travel time of seismic waves between the source and the detector. Higher barometric pressure (corresponding to greater stress on the rock) meant less travel time – the seismic waves moved faster because tiny cracks in the rock closed up under pressure.



During the second month of data collection, the quality of the data actually improved, but the researchers detected two anomalous departures from the established relation of barometric pressure to travel time. These excursions corresponded to two earthquakes in the Parkfield region, an area so well instrumented that earthquake magnitude and location, including depth, can be determined with great precision. One earthquake measured magnitude 3, the largest local event during the observation period; the other earthquake measured magnitude 1, but occurred closer to the experiment.



The excursions in the travel-time data began 10 hours before the magnitude 3 event and 2 hours before the magnitude 1 event. In earlier, laboratory-based studies of the relationship of seismic-wave travel times and stress, such “preseismic” changes were related to changes in the properties of microcracks in the rock.



“The same may be the case here,” says Daley. “But in fact we do not have a clear physical explanation for these preseismic observations as yet, although they plausibly represent stress changes in the crust. Our goal is to determine if they are repeatable and, if so, to determine the ultimate physical basis. Nevertheless, what we’ve seen are interesting stress changes associated with earthquakes. It encourages us to continue this kind of observation.”



Says Rice’s Fenglin Niu, “Detecting a preseismic velocity change is at best only a small step toward reliable earthquake prediction. Before we can supply any useful information before an earthquake, we will need a physical model that can explain when such a velocity change would occur before a quake.”



“Preseismic velocity changes observed from active source monitoring at the Parkfield SAFOD drill site,” by Fenglin Niu, Paul G. Silver, Thomas M. Daley, Xin Cheng, and Ernest L. Majer, appears in the 10 July issue of Nature and is available online to subscribers at http://dx.doi.org/doi:10.1038/nature07111.