August 2015

Quantifying the impact of volcanic eruptions on climate

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Large volcanic eruptions inject considerable amounts of sulphur in the stratosphere which, once converted into aerosols, block sun rays and tend to cool the surface of the Earth down for several years. An international team of researchers has just developed a method, published in Nature Geoscience, to accurately measure and simulate the induced drop in temperature. 
 
Considered the most important volcanic event of the 20th century, the eruption of Mount Pinatubo (June 1991) injected 20 million tons of sulphur dioxide in the stratosphere and provoked a global cooling of 0.4°C on average. 
 
To quantify the temporary cooling induced by the largest eruptions over the last 1500 years, whose magnitude exceeded Mount Pinatubo's, scientists usually adopt two approaches : dendroclimatology which relies on the analysis of tree-ring based proxies and climate model simulations in response to the volcanic particles effect. But until now these two approaches delivered results that were quite contradictory, and this prevented scientists from accurately assessing the impact of major volcanic eruptions on climate. Simulations showed greater (between two and four times higher) and longer cooling than dendroclimatic reconstructions. This gap even led some geophysicists to doubt the capacity of tree-ring based proxies to measure the impact of past major volcanic events on climate and to question the models' ability in simulating precisely the climate response to strong volcanic forcings. 
 
Reconciliation of observational proxy and model evidence 
 
Today, researchers from the University of Geneva (UNIGE), Switzerland, the Institut Pierre Simon Laplace, IRD, the French Alternative Energies Commission (CEA) and the National Center for Scientific Research (CNRS), France, have managed to reconcile the two approaches and developed a method to evaluate accurately the consequences of future high-magnitude eruptions on climate to better anticipate their impact on our societies. 
 
In this multidisciplinary team, dendrochronologists came up with a new reconstruction of the Northern Hemisphere summer temperature in the last 1'500 years. This reconstruction is mainly based on maximum latewood density, a parameter which is very sensitive to temperature variations. Data has been collected throughout the Northern Hemisphere, from Scandinavia and Siberia all the way to Quebec, including Alaska, the Alps and the Pyrenees. The inclusion of density allowed clear detection of all major eruptions. Results show that the year following a large eruption is characterised by a greater cooling than asserted in previous reconstructions and that this cooling does not last for more than three years at an hemispheric scale. 
 
In parallel, using a sophisticated climate model, climate physicists calculated the drop in temperature caused by the two largest volcanic events of the last millennium, the Samalas and Tambora eruptions which both occured in Indonesia in 1257 and 1815. This model combines data about volcanoes location, the period of the eruption, the amount of sulphur dioxide injected, and integrates results from a microphysical model which simulates the volcanic aerosol life cycle from their formation, following the oxidation of sulphur dioxide, to their sedimentation and elimination from the atmosphere. " This unusual approach enables to realistically simulate the size of the volcanic aerosols particles and hence their life expectancy in the atmosphere, which directly influences both the extent and persistence of the cooling induced by an eruption ", explains Markus Stoffel, researcher at UNIGE. These new simulations show that disruption in ray exchange, caused by volcanic activity, were largely overestimated in previous climate simulations, used in the latest IPCC (Intergovernmental Panel on Climate Change) report. 
 
For the first time, results provided by reconstructions and climate models about the intensity of cooling converge and demonstrate that the Tampora and Samalas eruptions generated an average drop in temperature in the Northern Hemisphere fluctuating between 0.8 and 1.3°C during the summer 1258 and 1816. Both approaches also agree on the average persistence of the significant cooling which is estimated at two to three years. These results pave the way to a better assessment of the role played by volcanism on climate change. 
 
 Provided by: University of Geneva </div>

Quantifying the impact of volcanic eruptions on climate

Large volcanic eruptions inject considerable amounts of sulphur in the stratosphere which, once converted into aerosols, block sun rays...

Properties of magma influence volcano forecasts

Magma, News, volcano 8:55 PM

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Many volcanoes are located in densely settled areas. Every time one of these becomes active, large populations are put at risk. Hence, one of the primary goals of the current generation of volcanologists is to develop tools that can accurately predict when volcanoes will erupt. In the case of an impending eruption, these tools are of key importance to those charged with making decisions about what action to take and when. 
  Under Prof. Dingwell's supervision, a team of geophysicists has now simulated volcanic eruptions in the laboratory, and asked how well current forecasting models succeed in predicting their properties. "To this end, we have carefully monitored the behavior of samples of synthetic magmas under pressure and recorded the micro-signals that herald their ultimate failure," says Jeremie Vasseur, a PhD student in Dingwell's group and first author of the study. "Analyzing these precursory signals and how they evolve is akin to analyzing the seismic signals prior to an eruption." Vasseur and his colleagues found that the more heterogeneous the synthetic magma, the more accurately one can predict its failure. Conversely, the forecast becomes progressively less precise as the starting material becomes more homogeneous. The properties of the magma in real volcanoes also vary widely, depending on the extent to which gas-bubbles and crystalline inclusions are trapped in the otherwise homogeneous liquid. "Our results imply that the key to forecasting eruptions lies in knowing just how heterogeneous the magma is," says Dingwell. "We will continue our efforts to understand the behavior of magmas in the hope that a comprehensive forecasting tool will someday be within our grasp, he adds. 
 
 
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The above post is reprinted from <a href="http://www.en.uni-muenchen.de/news/newsarchiv/2015/dingwell_vulkanausbrueche.html" rel="nofollow" style="background-color: transparent; border-radius: 0px ! important; box-sizing: border-box; color: #4c7a9f; text-decoration: none;" target="_blank">materials</a> provided by <a href="http://www.en.uni-muenchen.de/index.html" rel="nofollow" style="background-color: transparent; border-radius: 0px ! important; box-sizing: border-box; color: #4c7a9f; text-decoration: none;" target="_blank">Ludwig-Maximilians-Universitaet Muenchen (LMU)</a>. Note: Materials may be edited for content and length.</div>
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Properties of magma influence volcano forecasts

Many volcanoes are located in densely settled areas. Every time one of these becomes active, large populations are put at risk. Hence, ...

The Supervolcano Under Yellowstone is Alive and Kicking

USA, volcano, Yellowstone 9:31 PM

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<tr><td class="tr-caption" style="text-align: center;">Gazette chief photographer Larry Mayer's image of a small plane flying over Grand Prismatic Spring in Yellowstone National Park</td></tr>
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 The wind shifts. The stench of rotten eggs makes it nearly impossible to breathe and the hot fog clouds my view. I hold my breath and close my eyes, imagining the fog growing thicker, crushing me. Then without warning the wind clears and I’m enveloped once again in the cold, dry air. The heat feels like a lost dream. I shiver as I analyze my surroundings. Before me lies a steaming blue spring with concentric rings of green, yellow and dark red. I turn around to see another pool. But the rising fog is so dense, I can only guess at the existence of blue water below. Sometimes I glimpse bubbles boiling from some unknown source. The pools are a small sampling of the 10,000 geothermal features that dot Yellowstone’s caldera and hint at a mysterious hot spot beneath the crust. It’s this alien landscape that makes it surprisingly easy to believe that northwestern Wyoming sits directly above a supervolcano — a behemoth far more powerful than your average volcano, with the capacity to eject more than 240 cubic miles of material. But why do scientists believe there is a supervolcano hidden below? When I asked Henry Heasler, a park geologist at Yellowstone this question, he waxed philosophical. “Good science is nothing more than a progress report,” he said. “It’s what we know at a certain time with the data that we have.” 
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 And this year scientists provided one of the most impressive progress reports yet: They peered deep beneath the Earth’s surface and created the first three-dimensional image of the supervolcano’s plumbing. Although they had already imaged a plume, which brings molten rock up from deep below the mantle to a region about 60 kilometers below the surface, and a magma chamber about 10 kilometers below the surface, the new work had found the missing link between the two. A second, 11,200-cubic-mile magma chamber connects the plume to the shallower magma chamber. It’s 4.5 times larger than its shallow companion and has enough hot rock to fill the Grand Canyon nearly 14 times. Hsin-Hua Huang, a seismologist from the University of Utah and his colleagues used earthquake data to capture this astonishing image. It’s similar to an ultrasound, said Heasler. “We have the skin of a surface—of a person—but we want to see what’s inside.” When earthquakes travel through dense, hot spots they slow down. So if a seismic wave reaches a sensor later than expected, scientists know there’s a low-velocity, and hence denser and hotter, region hidden deep within the Earth. “If we were just using one pathway—so one earthquake and one seismometer—we couldn’t be able to tell where along that path that low velocity body was. We’d have no idea,” said co-author Jamie Farrell from the University of Utah. That’s where multiple earthquakes and sensors come into play. Huang’s team used 4,849 earthquakes, originating from all parts of the earth, plus 80 seismographs across Yellowstone and beyond, to create a rough three-dimensional picture. Their study was also the first to combine both worldwide and local earthquakes. Distant earthquakes allow scientists to image deep structures (any earthquakes originating under India or China will first travel through the Earth’s core before reaching the U.S.) and local earthquakes allow for shallow structures. Combining the two let the team image the deep magma chamber for the first time. Given that natural earthquakes, however, are relatively rare events—even in one of the most active areas in the world—they had to collect 30 years worth of data. But seismic tomography isn’t the only way to peer deep underground. GPS satellites can scour the area searching for any ground movement; gravity satellites can look for any changes in the density below; and ground instruments can sample the heat and gases rising from the geothermal features. 
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All methods point to a supervolcano that’s very much alive. From 1976 to 1984, GPS satellite data showed that the caldera floor was swelling upward. Magma was flowing from the deeper chamber into the shallow reservoir, causing the above ground to inflate. This influx of hot material, which happens to be less dense, was also reflected in gravity data. To a satellite orbiting directly above the inflow, the Earth will seem to pull on it a little less than expected. Meanwhile ground instruments measured increasing heat and gases rising from the active features. Then from 1985 to 1995 the caldera sunk back down about 5.5 inches. Magma was either moving out of the system laterally or the shallow reservoir was simply cooling and contracting, letting gases seep through the surface. Later measurements show that the caldera floor is continuing to swell and sink. But scientists still don’t understand the complex interplay between the supervolcano’s moving parts. “I think our next step—hopefully—is to be able to look at some smaller scale features of how these bigger features are connected to each other,” said Farrell. If scientists can determine how the large magma chambers interact with each other, they will better understand how fluids and heat move the Earth. “Then we can start looking at how long it would take for enough material to get from the deep to the shallow [reservoirs] and maybe where we are in the volcanic cycle of eruptions. But we’re not quite there yet.” Although past eruptions dot the Earth’s surface from Oregon to Wyoming, it’s hard to infer anything about a future eruption. And Farrell isn’t convinced another super-eruption will happen at all. “The system might be dying,” he said. “The Yellowstone hot spot is moving into thicker, colder continental crust. And it takes a lot more energy to burn through that crust than it did the thinner crust that it’s been burning through for the last 17 million years.” But as I watch Yellowstone’s surface boil over before my very eyes it’s hard to believe that the system deep beneath my feet might one day fade away. And as a geyser before me erupts, shooting steam and water tens of feet into the air, I have to wonder if it’s instead slowly building toward another super-eruption. After all, despite Farrell’s uncertainty, he continued to say: “It’s happened in the past, it could happen in the future.” 
 
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The Supervolcano Under Yellowstone is Alive and Kicking

Gazette chief photographer Larry Mayer's image of a small plane flying over Grand Prismatic Spring in Yellowstone National Park The...

6.3 Magnitude Earthquake Strikes Off Oregon Coast

Earthquakes, News 7:18 PM

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The United States Geological Survey says a 6.3 magnitude earthquake has struck roughly 170 miles off the coast of Oregon, in the western United States. 
 
The earthquake was detected south of Portland, in an area that has a relatively small population. 
 
The National Oceanic and Atmospheric Administration's Tsunami Warning Centre did not immediately issue a tsunami warning for the area after the earthquake was detected. 
 
The tremor comes just after the Pacific Northwest Seismic Network reported detecting more than 4,500 small earthquakes over a two week span, deep underneath the Olympic Peninsula and outer Vancouver Island. The areas impacted by those tremors also included an area spanning from near Eugene, Oregon — close to where the Thursday earthquake was seen — down to the Siskiyou Mountains in northern California. 
 
Those earthquakes were part of a phenomenon known to scientists as "episodic tremor and slip" or "slow slip", which apparently happens on a regular basis along Cascadia's tectonic plate boundary. 
 
The earthquake struck 178 miles off the coast of Coos Bay, USGS reported. There is no threat of a tsunami from this earthquake, the USGS said. 
 
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A M6.3 earthquake has occured 284km WNW of Bandon, Oregon. No tsunami warning has been issued. More here: <a href="https://t.co/uyXClrJ8Rf">https://t.co/uyXClrJ8Rf</a> including a Did You Feel It? link <a href="https://t.co/B8LVW0BrXy">pic.twitter.com/B8LVW0BrXy</a></div>
— USGS (@USGS) <a href="https://twitter.com/USGS/status/1167107185895256065?ref_src=twsrc%5Etfw">August 29, 2019</a></blockquote>
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6.3 Magnitude Earthquake Strikes Off Oregon Coast

The United States Geological Survey says a 6.3 magnitude earthquake has struck roughly 170 miles off the coast of Oregon, in the wester...

Impact origin of archean cratons: Learning from Venus

NASA, News 9:21 PM

Impact origin of archean cratons: Learning from Venus

Figure 5 from Hansen is a cross-sectional illustrations of Venus and Earth showing endogenic and exogenic geodynamic processes through t...

Staying safe in sandy beaches

environmental, News 9:15 PM

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Monitoring beach sand to safeguard human health</h2>
Beach sand contains all kinds of microorganisms, including those that can harm human health. Yet current guidelines are focused exclusively on monitoring the levels of microbes in the water. Now, an international panel of scientists is recommending monitoring the sand at recreational beaches, to minimize health risks for beachgoers.  
 
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Now, an international panel of scientists is recommending monitoring 
the sand at recreational beaches, to minimize health risks for 
beachgoers. Their advice is based on the general consensus reached 
during the international conference "Trends in Environmental 
Microbiology and Public Health," held in Lisbon Portugal in September 
2014. 
 
"Beach sands accumulate contaminants and people can get exposed to 
these contaminants during beach recreational activities," said 
Solo-Gabriele, professor at the University of Miami College of 
Engineering, corresponding and first author of a paper that summarizes 
the findings. "Hopefully this paper will make a difference in convincing
 regulators of the need to include sand in beach monitoring programs." 
 
The article, published in the July issue of the Journal of the Marine Biological Association of the United Kingdom,
 reflects the international experience of all scientific and technical 
papers published up to date, including data from beaches in the U.K., 
Portugal and the U.S. 
 
"This publication is a landmark paper," said João Brandão, manager of
 the sand microbiology and public health programme at the National 
Institute of Health in Portugal, national delegate for the European 
Confederation of Medical Mycology and co-author of the paper. "It wraps 
it all up and hopefully lays down the foundation for the future." 
 
Many of the studies used to develop recommendations were conducted in
 South Florida including Hobie Beach, along the Rickenbacker Causeway, 
as you enter Key Biscayne. Other beach locations in the U.S. included 
the Great Lakes, Hawaii and California. 
 
Previous studies have shown that the swash zone of the beach 
environment, with the wetting and drying processes and the presence of 
seaweed, algae and sargassum, is prone to regrowth of disease-causing 
microbes, including unhealthful bacteria, viruses, nematode larva and 
eggs and harmful yeast and fungi. 
 
The scientists explain that since 2003, there is a World Health 
Organization recommendation to perform epidemiological studies of the 
impact of sand quality on bathers' health and to set surveillance 
strategies. Yet, so far, "unfortunately no country has implemented this 
recommendation." 
Specific recommendations of the current paper include: 
<ul>
<li>Identification
 of the disease causing agent(s). With this understanding, effective 
control and monitoring programs can be implemented</li>
<li>Methods that estimate public health risks from various pathogens in the sand</li>
<li>Studies that can assess exposure to microbes in the sand by contact, ingestion and inhalation</li>
<li>Indicators, other than FIOs (fecal indicator organisms), to determine the presence of sewage and human waste</li>
<li>Detection and quantification of microbe levels for specific pathogens</li>
<li>Determine
 if FIOs are indicative of fecal pollution that carries pathogens, or 
separated from their original source through survival and regrowth.</li>
<li>Tools to identify sources of pathogens</li>
<li>Regulatory standards that reflect microbial sources, the pathogens they contain and the associated health risks.</li>
<li>Reliable sand collection methods that take in consideration that pathogen contamination at sandy beaches tends to be patchy.</li>
<li>Determination of beach sand quality at freshwater vs. marine beaches</li>
<li>Assess beach sand quality based on contamination by land-and-air</li>
<li>Standardized methods to recover and disinfect FIOs and pathogens from different types of sands.</li>
</ul>
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The above post is reprinted from <a href="http://news.miami.edu/stories/2015/08/health-concerns-in-beach-sand.html" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.miami.edu/" rel="nofollow" target="_blank">University of Miami</a>. Note: Materials may be edited for content and length.</div>

Staying safe in sandy beaches

Monitoring beach sand to safeguard human health Beach sand contains all kinds of microorganisms, including those that can harm human ...

Historic 2013 Colorado Front Range storm accomplished up to 1,000 years of erosion

Earth History, landslides, sedimentary 9:06 PM

Historic 2013 Colorado Front Range storm accomplished up to 1,000 years of erosion

Colorado Front Range The historic September 2013 storm that triggered widespread flooding across Colorado's Front Range eroded the ...

What would a tsunami in the Mediterranean look like?

earth, tsunami 10:24 PM

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<tr><td class="tr-caption" style="text-align: center;"> Animation showing water elevation for an earthquake-induced tsunami at the Southwest of Crete. Credit: Samaras et al., Ocean Science, 2015. The copyright holder has authorised the use of this image under the conditions specified by the Creative Commons Attribution-ShareAlike licence.</td></tr>
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Researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African plate slides underneath the Eurasian plate. About 10% of all tsunamis worldwide happen in the Mediterranean, with on average, one large tsunami happening in the region once a century. The risk to coastal areas is high because of the high population density in the area -- some 130 million people live along the sea's coastline. Moreover, tsunami waves in the Mediterranean need to travel only a very short distance before hitting the coast, reaching it with little advance warning. The new study shows the extent of flooding in selected areas along the coasts of southern Italy and Greece, if hit by large tsunamis in the region, and could help local authorities identify vulnerable areas. 
 "The main gap in relevant knowledge in tsunami modelling is what happens when tsunami waves approach the nearshore and run inland," says Achilleas Samaras, the lead author of the study and a researcher at the University of Bologna in Italy. The nearshore is the zone where waves transform -- becoming steeper and changing their propagation direction -- as they propagate over shallow water close to the shore. "We wanted to find out how coastal areas would be affected by tsunamis in a region that is not only the most active in the Mediterranean in terms of seismicity and tectonic movements, but has also experienced numerous tsunami events in the past." 
 
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<tr><td class="tr-caption" style="text-align: center;"> The maps on the left-hand side show the location and elevation of the low-lying coastal areas in south-southwest Crete (top) and in east-southeast Sicily (bottom). The ones on the right show the areas in these two locations that would be inundated in the earthquake-induced tsunami scenarios studied. The coloured lines are terrain-elevation contours. Credit: Samaras et al., Ocean Science, 2015; base images from Google Earth, 2015</td></tr>
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 The team developed a computer model to represent how tsunamis in the Mediterranean could form, propagate and hit the coast, using information about the seafloor depth, shoreline and topography. "We simulate tsunami generation by introducing earthquake-generated displacements at either the sea bed or the surface," explains Samaras. "The model then simulates how these disturbances -- the tsunami waves -- propagate and are transformed as they reach the nearshore and inundate coastal areas." As detailed in the Ocean Science study, the team applied their model to tsunamis generated by earthquakes of approximately M7.0 magnitude off the coasts of eastern Sicily and southern Crete. Results show that, in both cases, the tsunamis would inundate the low-lying coastal areas up to approximately 5 metres above sea level. The effects would be more severe for Crete where some 3.5 square kilometres of land would be under water. "Due to the complexity of the studied phenomena, one should not arbitrarily extend the validity of the presented results by assuming that a tsunami with a magnitude at generation five times larger, for example, would result in an inundation area five times larger," cautions Samaras. "It is reasonable, however, to consider such results as indicative of how different areas in each region would be affected by larger events." "Although the simulated earthquake-induced tsunamis are not small, there has been a recorded history of significantly larger events, in terms of earthquake magnitude and mainshock areas, taking place in the region," says Samaras. For example, a clustering of earthquakes, the largest with magnitude between 8.0 and 8.5, hit off the coast of Crete in 365 AD. The resulting tsunami destroyed ancient cities in Greece, Italy and Egypt, killing some 5000 people in Alexandria alone. More recently, an earthquake of magnitude of about 7.0 hit the Messina region in Italy in 1908, causing a tsunami that killed thousands, with observed waves locally exceeding 10 metres in height. The team sees the results as a starting point for a more detailed assessment of coastal flooding risk and mitigation along the coasts of the Eastern Mediterranean. "Our simulations could be used to help public authorities and policy makers create a comprehensive database of tsunami scenarios in the Mediterranean, identify vulnerable coastal regions for each scenario, and properly plan their defence." 
 
Animation: <a href="http://www.egu.eu/medialibrary/image/1504/sicily-tsunami-animation/" rel="nofollow" target="_blank" title="http://www.egu.eu/medialibrary/image/1504/sicily-tsunami-animation/">http://www.egu.eu/medialibrary/image/1504/sicily-tsunami-animation/</a> 
 
The above post is reprinted from <a href="http://www.egu.eu/news/190/what-would-a-tsunami-in-the-mediterranean-look-like/" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.egu.eu/" rel="nofollow" target="_blank">European Geosciences Union (EGU)</a>. Note: Materials may be edited for content and length. 
 </div>

What would a tsunami in the Mediterranean look like?

Animation showing water elevation for an earthquake-induced tsunami at the Southwest of Crete. Credit: Samaras et al., Ocean Science, 20...

Mechanism behind 'strange' earthquakes discovered

Earhquakes, earth 9:47 PM

Until now, the cause of that seismicity has remained unclear.

While earthquakes along tectonic plate boundaries are caused by 
motion between the plates, earthquakes away from fault lines are 
primarily driven by motion beneath the plates, according to a new study 
published by USC scientist Thorsten Becker in Nature on Aug.

Just beneath the Earth's crust is a layer of hot, semi-liquid rock 
that is continually flowing -- heating up and rising, then cooling and 
sinking. That convective process, interacting with the ever-changing 
motion of the plates at the surface, is driving intraplate seismicity 
and determining in large part where those earthquakes occur. To a lesser
 extent, the structure of the crust above also influences the location, 
according to their models.

"This will not be the last word on the origin of strange earthquakes.
 However, our work shows how imaging advances in seismology can be 
combined with mantle flow modeling to probe the links between seismicity
 and mantle convection," said Becker, lead author of the study and 
professor of Earth sciences at the USC Dornsife College of Letters, Arts
 and Sciences.

Becker and his team used an updated mantle flow model to study the 
motion beneath the mountain belt that cuts north to south through the 
interior of the Western United States.

The area is seismically active -- the reason Yellowstone has geysers 
is that it sits atop a volcanic hotspot. Previously, scientists had 
suggested that the varying density of the plates was the main cause. 
(Imagine a mountain's own weight causing it to want to flow apart and 
thin out.)

Instead, the team found that the small-scale convective currents 
beneath the plate correlated with seismic events above in a predictable 
way. They also tried using the varying plate density or "gravitational 
potential energy variations" to predict seismic events and found a much 
poorer correlation.

"This study shows a direct link between deep convection and shallow 
earthquakes that we didn't anticipate, and it charts a course for 
improved seismic hazard mapping in plate interiors," said Tony Lowry, 
co-author of the paper and associate professor of geophysics and 
geodynamics at Utah State University. 
 
 
The above post is reprinted from <a href="http://news.usc.edu/85475/a-crusty-mystery-scientists-dig-into-the-origin-of-strange-earthquakes/" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.usc.edu/" rel="nofollow" target="_blank">University of Southern California</a>. The original item was written by Robert Perkins. Note: Materials may be edited for content and length.

</div>
</div>

Mechanism behind 'strange' earthquakes discovered

Seismicity on the North American plate occurs as far afield as southern Missouri, where earthquakes between 1811 and 1812 estimated at ar...

Change in the Color of Amethyst Crystals

gemstones, Mineralogy 8:54 PM

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<tr><td class="tr-caption" style="text-align: center;">Changes in color of amethyst by heat treatment and UV radiation. 
Credit: Amir Akhavan</td></tr>
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The color in amethyst from most localities is unevenly distributed in the individual crystals. In amethyst geodes it is often most intense in the growth zones under the rhombohedral faces. 
 
Occasionally the color is deeper under either the r or z rhombohedral faces, giving the crystal a pinwheel appearence when viewed from the top. In prismatic crystals the color may appear in phantom-like thin layers, while in scepters and skeleton quartz the color is often concentrated along the edges, and accompanied by smoky zones. 
 
When heated to more than about 300-400°C, amethyst loses its violet color and often turns yellow, orange or brown, and then resembles the quartz variety citrine, but depending on the locality and the temperature during the heat treatment it may also turn colorless or - rarely - green. 
 
Irradiation with UV light will also destroy the color centers, and accordingly prolonged exposure to sunlight will slowly fade amethyst. The photo to the right shows the effects of heat (bottom left and right) and UV irradiation (top right) on the color of a specimen from Uruguay. 
 
Amethyst is pleochroic when the polarization of the light is changed from parallel to the c-axis to perpendicular to the c-axis, amethyst changes its color from blue-violet to purple. The strength of the effect varies to a considerable degree, and changes in the hue depending on the direction of the transmitted light may be observable with the naked eye, in particular in crystals with a zonar development of color, which may even show sky-blue tones. 
 
 
A part of a deeply colored amethyst geode from Rio Grande Do Sul was cut into four pieces. Three of them were treated with heat or UV radiation. The four pieces were glued together again after treatment.</div>
 
<ul style="text-align: left;">
<li> Top Left: Untreated, original color. Color seems to be evenly distributed in the tips, but is most intense 1-4 mm under the rhombohedral crystal faces.</li>
<li> Top Right: Exposed to UV light from two 18W low pressure mercury lamps (germicidal UV-C lamps) for 3 months. The crystals have lost almost all their color, but some slightly violet patches are still visible inside some crystals. Fading proceeds relatively quickly in the beginning, but slows down with time. The complete bleaching would probably have required another 2-3 months of exposure.</li>
<li> Bottom Left: Heating to about 380°C for 8 hours resulted in loss of most violet color and an overall patchy appearence. Some crystals are still colored violet in central parts while the outmost layers of the rhombohedral faces start to develop a yellow-brown color.</li>
<li> Bottom Right: Heating to about 450°C for 12 hours. The violet color is gone, and a orange-brown color appears that is most intense close to the surface. Note that the most intense violet color of the untreated crystals is not directly at the surface, but a few millimeters inside the crystals.</li>
</ul>
 
 </div>

Change in the Color of Amethyst Crystals

Changes in color of amethyst by heat treatment and UV radiation. Credit: Amir Akhavan The color in amethyst from most localities is ...

Rolling in the deep: Mantle flow stress best indicator of US intermountain seismicity

News, Seismic, USA 9:54 PM

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<tr><td class="tr-caption" style="text-align: center;"> A June 2015 map of the USArray component of the National Science Foundation-funded Earthscope project. Earthscope is a continental-scale seismic observatory designed to support integrated studies of continental lithosphere and deep Earth structure. Scientists from Utah State University, the University of Southern California, Roma Tre University, the University of New Mexico, Scripps and MIT used data collected from the project to study seismicity of the Intermountain Seismic Belt. They published findings in Nature. Credit: Earthscope. </td></tr>
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 Much of what we understand about earthquakes is based on plate tectonics. But for residents of Utah's seismically restless Wasatch Front, a 120-mile-long metropolitan region anchored by Salt Lake City and bounded by the steep Wasatch Mountains and Great Salt Lake, such theory has fundamental limitations. Because the state's population center sits deep within the interior of the North American Plate, reasons why the Wasatch Fault is earthquake-prone, while other parts of the state are quieter, are poorly understood. Plate motions across California's San Andreas Fault, the Utah capitol's nearest plate boundary some 760 miles away, don't give a clear picture of what's happening across the Beehive state and other areas of the Intermountain Seismic Belt, says Utah State University geophysicist Tony Lowry. "In continental interiors, we know little about the forces that drive the earthquake cycle," he says. "We rely mostly on the history of past earthquakes to assess hazards. But, because seismic observations cover only a tiny fraction of the time between the largest earthquakes, we can easily miss important parts of the story." Lowry suggests mantle flow stress, occurring deep within the earth, gives new insight into potential hazards that could shake the intraplate belt, which stretches from southwestern Utah up through Idaho and Wyoming to Yellowstone National Park and north through western Montana to Canada. He and colleagues Thorsten Becker of the University of Southern California, Claudio Faccenna of Italy's Roma Tre University, Brandon Schmandt of The University of New Mexico, Adrian Borsa of the University of San Diego's Scripps Institution of Oceanography and Chunquan Yu of the Massachusetts Institute of Technology publish the foundation of an emerging model in the August 27, 2015 issue of Nature. Their research is supported by the National Science Foundation. "We've explored various aspects of how and why rocks break and flow, but this is the first time we've recognized the importance of deep mantle flow," says Lowry, associate professor in USU's Department of Geology. "This developing model gives us a new tool for understanding what makes earthquakes tick." In the past decade or so, researchers have focused on three possible mechanisms driving earthquakes. One is variations in gravitational potential energy, another is changes in thickness of the earth's crust along the Intermountain Belt and the third is changes in strength of the lithosphere; that is, the crust and upper mantle. Using new seismic and GPS data available from the massive NSF-funded Earthscope array across the western United States, the researchers looked at these observations simultaneously and found some surprises.   <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;"> Illustration of the massive EarthScope GPS receiver array across the United States. The National Science Foundation-funded project is a continental scale observatory designed to support integrated studies of continental lithosphere and deep Earth structure. Scientists from Utah State University, the University of Southern California, Roma Tre University, the University of New Mexico, Scripps and MIT used data collected from the project to study seismicity of the Intermountain Seismic Belt. They published findings in Nature. Credit: Earthscope. </td></tr>
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 "In our earlier work, we tried to understand how deep mantle flow contributed to high elevations in the western United States," Lowry says. "Thorsten (Becker) pushed us to explore whether or not elevation changes predicted by the same mantle flow models could explain the uplift we were observing with the Earthscope GPS measurements." It turns out the model did a poor job of explaining the GPS uplift, but gave a remarkable approximation of where to find earthquake belts because the upward push by mantle flow instead stretches the strong upper layer where earthquakes occur. "Our findings represent the birth of a new idea and lay the groundwork for a better understanding of earthquakes," Lowry says. "We now know we need to be looking for the impetus – that nudge that sets an earthquake system in motion – from flow at depths of 60 to 100 miles, much deeper than where we'd been looking." Becker, lead author on the paper, says the team's work won't be the last word on the origin of intraplate earthquakes. "Our work shows how imaging advances in seismology can be combined with mantle flow modeling to probe the links between seismicity and mantle convection," he says. Provided by: Utah State University 
</div>

Rolling in the deep: Mantle flow stress best indicator of US intermountain seismicity

A June 2015 map of the USArray component of the National Science Foundation-funded Earthscope project. Earthscope is a continental-scale...

Geologic record of ancient earthquakes and tsunamis will help understand future impacts

Earhquakes, earth, tsunami 9:42 PM

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 The devastating 2004 Indian Ocean earthquake and tsunami that killed 230,000 people has raised questions among coastal residents about when the next big tsunami will strike. It's a question that University of Rhode Island geologist Simon Engelhart knows cannot be answered with any precision. But he and colleagues from Humboldt State University, Rutgers University and the Earth Observatory of Singapore, in collaboration with geologists from Indonesia, examined the geological record in northern Sumatra to better understand how frequently large earthquakes and tsunamis occur there. The research was published in the August edition of the journal Geology. What they found was evidence that five to seven major tsunamis had occurred between 7,400 and 3,800 years ago, with an additional four to six tsunamis since that time. "We can surmise from this that a major earthquake and tsunami occurred about every 600 to 900 years," said Engelhart, URI assistant professor of geosciences. "But those are maximum recurrences. We're not at a point where we can predict earthquakes." The researchers examined a dozen sediment cores up to 6 meters long from two sites near the shoreline of Sumatra's Aceh province. Within the sediments in the cores were three layers of soil containing mangrove pollen that dropped into the intertidal zone during earthquakes and were buried by tidal flat sediments. Sands above the soils contained species of marine organisms called foraminifera that live far offshore, evidence that the sand was brought onshore by ancient tsunamis. Radiocarbon dating of these soil layers and associated sands found that local earthquakes causing tsunamis occurred about 7,000, 5,800 and 3,800 years ago. Two turbid layers in the cores containing more oceanic foraminifera were evidence of additional tsunamis that took place during the same period. "The archive of sedimentary evidence in the cores doesn't tell the whole story, though," Engelhart said. "We had to figure out what the sea level was doing for the last 8,000 years to identify when we would find geological records of earthquakes and tsunamis." According to Engelhart, sea level rose rapidly in the Indian Ocean up until about 8,000 years ago, when it slowed to a rate that allowed sediment to accumulate in predictable layers, enabling present-day scientists to study the environment of the time. About 3,800 years ago, however, sea level gradually stopped rising and sediments no longer accumulated. Instead, wave action mixed up the newer sands, blurring the historic chronology. Even so, the research team was able to calculate the proportion of sediment that came from offshore in tsunamis by examining the number of fossilized forams that are typically found far out at sea. From this, they concluded that four to six tsunamis struck Sumatra in the last 3,800 years. For Engelhart, part of the relevance of this study is in the realization of the importance of sea level in conducting this type of analysis. "You need to understand how sea level varied at a site before you can think about the methods to improve our understanding of how often earthquakes and tsunamis occur and how big they are," he said. "The relative sea-level history of this region demonstrates that we couldn't use the classic sedimentary methods to reconstruct earthquakes and tsunamis during the last 3,800 years at these sites." Understanding the relative sea-level history will be especially important when scientists conduct analyses of earthquake-prone areas like Alaska, Chile, Peru, Japan and New Zealand, all of which have sea level records that raise similar issues. Engelhart is already applying these findings to related studies in Alaska and the west coast of North America at Cascadia.  
 
 Provided by: University of Rhode Island 
</div>

Geologic record of ancient earthquakes and tsunamis will help understand future impacts

The devastating 2004 Indian Ocean earthquake and tsunami that killed 230,000 people has raised questions among coastal residents about wh...

Earth's Mineralogy Unique in the Cosmos

earth, Mineralogy 9:28 PM

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<tr><td class="tr-caption" style="text-align: center;"> Trapiche Emerald. Photo: StoneRockShop </td></tr>
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Research predicts that Earth has more than 1,500 undiscovered minerals and that the exact mineral diversity of our planet is unique and could not be duplicated anywhere in the cosmos. 
 
Minerals form from novel combinations of elements. These combinations can be facilitated by both geological activity, including volcanoes, plate tectonics, and water-rock interactions, and biological activity, such as chemical reactions with oxygen and organic material. 
 
Nearly a decade ago, Hazen developed the idea that the diversity explosion of planet's minerals from the dozen present at the birth of our Solar System to the nearly 5,000 types existing today arose primarily from the rise of life. More than two-thirds of known minerals can be linked directly or indirectly to biological activity, according to Hazen. Much of this is due to the rise of bacterial photosynthesis, which dramatically increased the atmospheric oxygen concentration about 2.4 billion years ago. 
 
In a suite of four related, recently published papers, Hazen and his team--Ed Grew, Bob Downs, Joshua Golden, Grethe Hystad, and Alex Pires--took the mineral evolution concept one step further. They used both statistical models of ecosystem research and extensive analysis of mineralogical databases to explore questions of probability involving mineral distribution. 
 
They discovered that the probability that a mineral "species" (defined by its unique combination of chemical composition and crystal structure) exists at only one locality is about 22 percent, whereas the probability that it is found at 10 or fewer locations is about 65 percent. Most mineral species are quite rare, in fact, found in 5 or fewer localities. 
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"Minerals follow the same kind of frequency of distribution as words in a book," Hazen explained. "For example, the most-used words in a book are extremely common such as 'and,' 'the,' and 'a.' Rare words define the diversity of a book's vocabulary. The same is true for minerals on Earth. Rare minerals define our planet's mineralogical diversity." 
 
Further statistical analysis of mineral distribution and diversity suggested thousands of plausible rare minerals either still await discovery or occurred at some point in Earth's history, only to be subsequently lost by burial, erosion, or subduction back into the mantle. The team predicted that 1,563 minerals exist on Earth today, but have yet to be discovered and described. 
 
The distribution of these "missing" minerals is not uniform, however. 
 
Several circumstances influence the likelihood of a mineral having previously been discovered. This includes physical characteristics, such as color. White minerals are less likely to have been noticed, for example. Other factors include the quality of crystallization, solubility in water, and stability near the surface of the planet. 
 
As such, Hazen and his colleagues predicted that nearly 35 percent of sodium minerals remain undiscovered, because more than half of them are white, poorly crystallized, or water soluble. By contrast, fewer than 20 percent of copper, magnesium, and copper minerals have not been discovered. 
 
Further expanding the link between geological and biological evolution, Hazen's team applied the biological concepts of chance and necessity to mineral evolution. In biology, this idea means that natural selection occurs because of a random "chance" mutation in the genetic material of a living organism that becomes, if it confers reproductive advantage, a "necessary" adaptation. 
 
But in this instance, Hazen's team asked how the diversity and distribution of Earth's minerals came into existence and the likelihood that it could be replicated elsewhere. What they found is that if we could turn back the clock and "re-play" Earth's history, it is probable that many of the minerals formed and discovered in this alternate version of our planet would be different from those we know today. 
 
"This means that despite the physical, chemical, and biological factors that control most of our planet's mineral diversity, Earth's mineralogy is unique in the cosmos," Hazen said. 
 
 
The above post is reprinted from <a href="https://carnegiescience.edu/node/1870" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.ciw.edu/" rel="nofollow" target="_blank">Carnegie Institution</a>.</div>

Earth's Mineralogy Unique in the Cosmos

Trapiche Emerald. Photo: StoneRockShop Research predicts that Earth has more than 1,500 undiscovered minerals and that the ex...

415-million-year-old fossil reveal that heavy metal pollution might have contributed to the world's largest extinction

Earth History, Fossils 9:20 PM

In a paper just published in Nature Communications, they 
present evidence that malformed fossil remains of marine plankton from 
the late Silurian (415 million years ago) contain highly elevated 
concentrations of heavy metals, such as iron, lead, and arsenic. These 
are well-known toxins that cause morphologic abnormalities in modern 
aquatic organisms; which led the authors to conclude that metal 
poisoning caused the malformation observed in these ancient organisms 
and may have contributed to their extinction and that of many other 
species.

Documented chemical behavior of these metals, which correlates with 
previously observed disturbances in oceanic carbon, oxygen and sulphur 
signatures, strongly suggests that these metal increases resulted from 
reductions of ocean oxygenation.

Thus, metal toxicity, and its expressions in fossilized 
malformations, could provide the 'missing link' that relates organism 
extinctions to widespread ocean anoxia. As part of a series of complex 
systemic interactions accompanying oceanic geochemical variation, the 
mobilisation of metals in spreading anoxic waters may identify the early
 phase of the kill-mechanism that culminated in these catastrophic 
events.

The recurring correlation between fossil malformations and 
Ordovician-Silurian extinction events raises the provocative prospect 
that toxic metal contamination may be a previously unrecognized 
contributing agent to many, if not all, extinction events in the ancient
 oceans.

</div>
 
 
The above post is reprinted from <a href="http://www.alphagalileo.org/ViewItem.aspx?ItemId=155666&CultureCode=en" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.ugent.be/" rel="nofollow" target="_blank">Ghent University</a>. Note: Materials may be edited for content and length. 
</div>

415-million-year-old fossil reveal that heavy metal pollution might have contributed to the world's largest extinction

Malformed (a) versus normal (b) plankton. Toxic metal contamination may be a previously unrecognized contributing agent to many, if not a...

Self-healing landscape: Landslides after earthquake

Earhquakes, landslides, News 5:42 PM

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In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks. Even after strong earthquake the activity of landslides returns back over the course of one to four years to the background level before the earthquake. 
 
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The interactions over time between earthquakes and processing shaping the landscape are still not well understood. The geoscientists have investigated areas affected by landslides related to four moderate to severe earthquakes (6.6 to 7.6 on Richter scale). "The main difficulty was that one must distinguish between the meteorological and the seismic causes of landsliding. Heavy rain can also produce landslides and can enhance landsliding after an earthquake," says GFZ scientists Marc Odin, the lead author of the study. Two processes are interacting here. A strong earthquake shakes soil layer loose from the underlying bedrock and also damages the rock below the top soil. Water seeps into the resulting the cracks and crevices and acts like a lubricating film on which a mountain slope slides into the valley.</div>
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With the present results of the team of geoscientists, this conceptual model has to be modified. "We analytically separated the effect of the rain from the seismic activity and so were able to determine that the decrease of landslides through time is based on an internal healing process of the landscape," said Marc Odin. The destabilization of the landscape caused by the quake gradually recovers. In the course of months to years, depending on weather, rocks and the strength of the earthquake, the slide rates return to the pre-earthquake level: The cracks slowly get closed again or are filled with sand and earth. The landscape self-heals its underlayer and returns to its background hazard potential.</div>
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This research is highly relevant: currently the GFZ analyzes these processes in the context of the Nepal-quake of April this year: "We had the chance to start a series of measurements directly after the quake and continue for the next few years," explained Niels Hovius, Head of the Section "Geomorphology" at the GFZ, about the current deployment of his team in the Himalayas.</div>
 
 
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The above post is reprinted from <a href="http://www.gfz-potsdam.de/en/media-communication/press-releases/details/article/selbstheilende-landschaften/" rel="nofollow" style="background-color: transparent; border-radius: 0px ! important; box-sizing: border-box; color: #4c7a9f; text-decoration: none;" target="_blank">materials</a> provided by <a href="http://www.gfz-potsdam.de/" rel="nofollow" style="background-color: transparent; border-radius: 0px ! important; box-sizing: border-box; color: #4c7a9f; text-decoration: none;" target="_blank">Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences</a>. Note: Materials may be edited for content and length.</div>
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Self-healing landscape: Landslides after earthquake

Ongoing debris fall mobilizing rock and dust from a landslide deposit due to the 2015 Gorkha In mountainous regions earthquakes often...

Monitoring Northwest Pacific Seismic Risks

Earhquakes, earth, Tectonic 9:24 PM

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 Early data coming in from a massive, four-year deployment of seismometers onshore and offshore in the Pacific Northwest are giving scientists a clearer picture of the Cascadia subduction zone, a region with a past and potential future of devastating 'megathrust' earthquakes. The preliminary results from the Cascadia Initiative include a report of previously undetected, small earthquakes offshore, and seismic imaging that reveals new offshore structures at the subduction zone. The reports, published as a focus section in the September-October 2015 issue of Seismological Research Letters (SRL), also provide an update on how well the Initiative's instruments are operating, including a look at how seafloor pressure monitors can detect tsunamis in the region. The Cascadia subduction zone (CSZ) is a 1,100-(680 mile) kilometer Pacific fault that runs roughly from Cape Mendocino, California in the south to northern Vancouver Island, British Columbia. The zone marks the place where the Juan de Fuca and Gorda tectonic plates slip beneath the North American plate at a rate of about 2.3 to 4 centimeters (.9 to 1.6 inches) per year. At subduction zones like this throughout the globe, the tremendous strain built up in these crustal collisions has been released in the world's largest recorded earthquakes. These megathrust quakes include the 2004 magnitude 9.1 Sumatran Andaman earthquake that devastated parts of Indonesia, and the 2011 magnitude 9.0 Tohoku earthquake in Japan. Although the CSZ has been relatively quiet in recent years, researchers have compiled a historical record of full and partial ruptures of the massive fault, with a magnitude 9.0 earthquake and tsunami last occurring in 1700. Scientists estimate that these megathrust quakes occur at 400 to 600-year intervals. Agencies such as the U.S. Federal Emergency Management Agency (FEMA) and others have warned of catastrophic damage along the U.S. Northwest coast in the wake of a megathrust quake. Funded from 2011 to 2015 by the National Science Foundation, the Cascadia Initiative was designed in part to collect information on the potential seismic threat of the CSZ. The project includes 27 new inland seismic stations, upgrades to 232 other land stations, and the deployment of 60 new seismometers on the ocean bottom, spread across the tectonic plates. The data collected by the initiative is openly available to the full scientific community in a database managed by the Incorporated Research Institutions for Seismology (IRIS) Data Management Center. The project "offers a unique opportunity to image the seismic structures associated with an entire plate, including its spreading center and subduction zone, within an easily accessible part of the continental and offshore United States," said University of Massachusetts Amherst researcher Haiying Gao, a guest editor of the SRL focus section. "I don't think we can predict the time or location of the next megathrust earthquake in the CSZ based on the current research progress," Gao cautioned. "Nevertheless, the Cascadia Initiative significantly contributes to a better understanding of the structure of the downgoing oceanic plates and thus to the assessment and mitigation of potential seismic and tsunamic hazards." For instance, a paper by New Mexico Tech researchers Emily Morton and Susan Bilek describes 96 small new earthquakes occurring in 2011 and 2012 that were detected with the help of the Initiative's ocean floor seismometers. These earthquakes occurred in the shallow, offshore "locked" part of the CSZ, where the fault is stuck in place, and had not been observed by land-based instruments. Detecting and locating these small seismic events can help researchers understand how strain on the megathrust fault may be changing, and to help predict how the megathrust might behave during a large rupture. The seismic data collected by the Initiative has also helped Gao and her colleague Yang Shen at the University of Rhode Island, along with another study by Columbia University scientist Helen Janiszewski and Cornell University researcher Geoffrey Abers, to compile a picture of the CSZ structure that points to new places where the crushing pressure of subduction is squeezing water from and transforming rock at the trench where the Juan de Fuca plate is bending under the North American plate. The newly deployed seafloor seismometers, said Gao, have offered an unprecedented look at how released fluid can affect the fault's strength and behavior at the offshore trench. Offshore instruments are important tools for observing and detecting tsunami risks in the region, according to a paper by Anne Sheehan of the University of Colorado Boulder and colleagues. They compared readings from several types of seafloor pressure gauges to study the tsunami caused by the 2012 Haida Gwaii earthquake, to evaluate how well the gauges could detect the timing and size of a tsunami. Other papers in the issue examine how deep sea sediments may affect seismic wave readings, and evaluate how the Cascadia Initiative's data collection from ocean bottom seismometers has improved over the first three years of the study. 
 
 
The above post is reprinted from <a href="http://www.eurekalert.org/pub_releases/2015-08/ssoa-cit081115.php" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.seismosoc.org/" rel="nofollow" target="_blank">Seismological Society of America</a>. Note: Materials may be edited for content and length.</div>

Monitoring Northwest Pacific Seismic Risks

Early data coming in from a massive, four-year deployment of seismometers onshore and offshore in the Pacific Northwest are giving scient...

Sublime Opalized Belemnite

Fossils, Minerals 8:56 PM

Sublime Opalized Belemnite

Photo :© Alias Collections Opalized Belemnite | ‪#‎Geology‬ Belemnitida is an extinct order of cephalopods which existed during th...

Beneath dangerous Ecuador volcano, only a few linger

News, volcano 9:21 PM

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 Bursts of ash spew from the snow-encircled crater of the Cotopaxi Volcano and fall in gusts on this village where the locals struggle to herd sheep and cattle to safety. Capped by glaciers, the 19,350-foot (5,987-meter) volcano is one of the world's most feared due to its location just 30 miles (50 kilometers) from the Ecuadorean capital Quito. Although officials say there currently is no such risk, a major eruption could hurl rock and mudflows into zones that are home to more than 300,000 people. The government has set a yellow precautionary alert, the lowest of three levels. Plenty of Ecuadoreans have been on edge since Cotopaxi began belching ash a week ago in columns more than 2 miles high, prompting President Rafael Correa to declare a state of emergency. On Saturday, explosions inside the volcano caused by magma meeting water sent a cloud of steam and ash more than a half mile (kilometer) above its rim. A day earlier, the volcano's penetrating sulfurous gases burned the nose and throat of Marco Toctauano, 32, as he chased a sheep down the mountain. The surgical mask shielding his nose and mouth was of little help little. The crater is less than 2 miles away. "We have cattle up on the mountainside. There's no more we can do," he said Friday. "With the ash, they're suffocating and could be dying. We're pretty bad, too."    <div class="separator" style="clear: both; text-align: center;">
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 Toctauano figures he's lost 17 or 18 head of cattle worth a total of some $7,500. A lot more could be lost if Cotopaxi were to blow. All but a quarter of Ticatitlin's 200 residents have evacuated. Those who remain are mostly elderly, like 84-year-old Adelaida Iza. She is more or less resigned to fate, noting as she cut alfalfa for her animals: "If the volcano blows, we're dead." Cotopaxi, which began to stir anew in April, saw its last major eruption in 1877, when it claimed more than 1,000 lives in a fast-moving flow of mud and debris, a destructive event known as a lahar. Ecuador's state of emergency allows the government to immediately assign funds for emergency measures but also includes elements that have drawn criticism from free speech advocates, such as suspension of the right to assemble. Also coming under criticism was Correa's insistence on censorship. Only the government may give information on Cotopaxi. A volcanologist at the state Geophysics Institute who normally provides The Associated Press with details on eruptions said he was afraid he'd lose his job if he commented. The government has identified potential shelters and sent police door-to-door in vulnerable areas. The hope is to ensure people are prepared to evacuate if needed, such as having emergency backpacks packed with food and first aid kits. Mayor Marcelo Tapia of San Ramon, a community on the volcano's skirt that also is threatened, told AP journalists that more and more people were leaving the village. "We're worried. We're more worried than ever," he said. "We don't know when disaster might strike." By Gonzalo Solano </div>

Beneath dangerous Ecuador volcano, only a few linger

Bursts of ash spew from the snow-encircled crater of the Cotopaxi Volcano and fall in gusts on this village where the locals struggle t...

Scientists Turn Oily Soil Into Fertile Ground

earth, environmental, soil 9:30 PM

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Rice University pyrolyzed oil-contaminated soil to reduce total petroleum hydrocarbons below federal standards, while leaving beneficial carbons in the soil. The lab grew lettuce in samples of reclaimed soil to test its viability.</div>
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 Scientists are cleaning soil contaminated by oil spills in a way that saves energy and reclaims the soil's fertility, using a process known as pyrolysis, which involves heating contaminated soils in the absence of oxygen. 
 
They use a process known as pyrolysis, which involves heating contaminated soils in the absence of oxygen. This approach is much better for the environment than standard incineration techniques for fast remediation, said Rice environmental engineer Pedro Alvarez. 
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"Our original goal was to speed the response to oil spills, but our aspiration was to turn contaminated soil into fertile soil," said Alvarez, the George R. Brown Professor and chair of Rice's Civil and Environmental Engineering Department. 
 
The new paper by Alvarez and his Rice colleagues in the American Chemical Society journal Environmental Science and Technology demonstrates how they've done just that. 
 
Off-shore oil spills tend to get the most attention, Alvarez said, but 98 percent of spills -- more than 25,000 per year -- occur on land. Industry and governments worldwide spend more than $10 billion annually to clean up oil spills. 
 
The Rice team found that pyrolyzing contaminated soil for three hours not only reduced the amount of petroleum hydrocarbons left to well below regulatory standards (typically less than 0.1 percent by weight), but also enhanced the soil's fertility by turning the remaining carbon into beneficial char. 
 
"We initially thought we could turn the hydrocarbons into biochar," Alvarez said. "We turned out to be partly wrong: We didn't get biochar, but [we got] a carbonaceous material that we call char and resembles coke. 
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"But we were correct in thinking that by removing toxic pollutants and the hydrophobicity that repels water that plants need, and by retaining some of the carbon and perhaps some of the nutrients, we would enhance plant growth," he said. 
 
The researchers proved that by successfully growing lettuce in reclaimed soil in the lab. "There's no one plant officially accepted as the standard for testing petroleum toxicity, but lettuce has been accepted by the community as very sensitive to toxins, especially petroleum," said Rice graduate student Julia Vidonish, the paper's lead author. "Reclaimed soil may not necessarily be used to grow food, but it certainly could be used for re-greening: planting grass to minimize erosion and to restore vegetation," Alvarez said. 
 
"Our process is part thermal desorption, but it takes advantage of petroleum chemistry," said Rice chemical engineer and co-author Kyriacos Zygourakis. "By heating the contaminated soils to about 420 degrees Celsius in the absence of oxygen, we first drive out the lighter hydrocarbons. That's the desorption part. But when the temperature gets above 350 degrees, the high-molecular-weight hydrocarbons, the resins and asphaltenes, undergo a series of cracking and condensation reactions to form solid char, similar to the petroleum coke produced in refineries. 
 
"We leave some of the hydrocarbons in the treated soil but in a solid, more benign form," he said. "The Environmental Protection Agency does not classify petroleum coke as hazardous waste. If, on the other hand, you want to remove everything, you have to raise the temperature even higher and introduce oxygen to incinerate the char. But you destroy the soil and use 40 to 60 percent more energy." 
 
The char produced by pyrolyzing oil-soaked soil is different from biochar, Rice biogeochemist and co-author Caroline Masiello said. Where biochar is a particle unto itself, the coke-like char appears to coat existing soil particles. 
 
"Biochar is a particle that is separate from the soil's mineral grains," she said. "It has an internal physical structure that allows it to hold water and nutrients and provides a home for microbes, but here, we're not making any of those things. We're making an organic film that coats the minerals." 
 
Vidonish said the process is scalable and should work with existing remediation equipment. "Incineration and thermal desorption are established technologies, and while this is different, there are similarities," she said. "We expect companies can take a mobile, field-scale thermal desorption unit and make a couple of modifications to do pyrolysis." 
 
"We proved we can remove all the bad actors and all the contaminants and at the same time have a final product with agricultural value," Zygourakis said. "We don't just turn it into desert sand." 
 
Much work remains to optimize the process, Vidonish said. "Moving forward, we want to understand how the pyrolysis time and the temperature affect the quality of the char in the soil," she said. 
 
 
The above post is reprinted from <a href="http://news.rice.edu/2015/08/20/scientists-turn-oily-soil-into-fertile-ground-2/">materials</a> provided by <a href="http://www.rice.edu/">Rice University</a>. </div>
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Scientists Turn Oily Soil Into Fertile Ground

Rice University pyrolyzed oil-contaminated soil to reduce total petroleum hydrocarbons below federal standards, while leaving benefici...

Geology In