Icelandic volcano sits on massive magma hot spot

Holuhraun fissure eruption on the flanks of the Bárðarbunga volcano in central Iceland on Oct. 4, 2014, showing the development of a lava lake in the foreground. Vapor clouds over the lava lake are caused by degassing of volatile-rich basaltic magma. Credit: Morten S. Riishuus, Nordic Volcanological Institute

Spectacular eruptions at Bárðarbunga volcano in central Iceland have been spewing lava continuously since Aug. 31. Massive amounts of erupting lava are connected to the destruction of supercontinents and dramatic changes in climate and ecosystems.

New research from UC Davis and Aarhus University in Denmark shows that high mantle temperatures miles beneath Earth's surface are essential for generating such large amounts of magma. In fact, the scientists found that the Bárðarbunga volcano lies directly above the hottest portion of the North Atlantic mantle plume.

The study, published online Oct. 5 and appearing in the November issue of Nature Geoscience, comes from Charles Lesher, professor of Earth and Planetary Science at UC Davis and a visiting professor at Aarhus University, and his former PhD student, Eric Brown, now a post-doctoral scholar at Aarhus University.

"From time to time the Earth's mantle belches out huge quantities of magma on a scale unlike anything witnessed in historic times," Lesher said. "These events provide unique windows into the internal working of our planet."

Such fiery events have produced large igneous provinces throughout Earth's history. They are often attributed to upwelling of hot, deeply sourced mantle material, or "mantle plumes."

Recent models have dismissed the role of mantle plumes in the formation of large igneous provinces, ascribing their origin instead to chemical anomalies in the shallow mantle.

Based on the volcanic record in and around Iceland over the last 56 million years and numerical modeling, Brown and Lesher show that high mantle temperatures are essential for generating the large magma volumes that gave rise to the North Atlantic large igneous provinces bordering Greenland and northern Europe.

Their findings further substantiate the critical role of mantle plumes in forming large igneous provinces.

"Our work offers new tools to constrain the physical and chemical conditions in the mantle responsible for large igneous provinces," Brown said. "There's little doubt that the mantle is composed of different types of chemical compounds, but this is not the dominant factor. Rather, locally high mantle temperatures are the key ingredient."

The research was supported by grants from the US National Science Foundation and by the Niels Bohr Professorship funded by Danish National Research Foundation.

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Source: University of California - Davis

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The tsunami-early warning system for the indian ocean: Ten years after

Technical concept of GITEWS.

The day after Christmas this year will mark the 10 anniversary of the tsunami disaster in the Indian Ocean. On 26 December 2004, a quarter of a million people lost their lives, five million required immediate aid and 1.8 million citizens were rendered homeless. The natural disaster, which caused extreme devastation over huge areas and the accompanying grief and anxiety, especially in Indonesia, Thailand and Sri Lanka exceeded the imaginable and reached such drastic dimensions, mainly due to the lack of a warning facility and a disaster management plan for the entire Indian Ocean region at this time.

Germany and the international community of states reacted with immediate support. Within the framework of the German Flood Victim Aid the Federal Government commissioned the Helmholtz Association of German Research Centres under the direction of the GFZ German Research Centre for Geosciences with the development of an Early Warning System for the Indian Ocean. From 2005 to 2011, with the large-scale project GITEWS (German-Indonesian Tsunami Early Warning System), the core of an integrated, modern, and effective Tsunami Early Warning System in Indonesia was established. With the follow-up project PROTECTS (Project for Training, Education and Consulting for Tsunami Early Warning Systems, 2011-2014) the personnel of the participating Indonesian institutions were trained to proceed independently and to take over responsibility for the operation of the Early Warning System as well as for the diverse technical and organizational components. In this ways PROTECTS which started in June 2011 and comprised a total of 192 training courses, internships, and hands-on-practice courses, covering all aspects of operation and maintenance of the Tsunami-Early Warning System contributed significantly to the sustainability of InaTEWS.

Under the auspices of the IntergovernmentalOceanographicCommission of UNESCO and with the collaboration of international partner institutes from Germany, the USA, China and Japan, GITEWS was integrated into a Tsunami Early Warning System for Indonesia. GITEWS was positively reviewed by a commission of international experts in 2010 and handed over to Indonesia in March 2011. Since then it has been providing its services under the name InaTEWS -- Indonesian Tsunami Early Warning System and is operated by the Indonesian Service for Meteorology, Climatology and Geophysics BMKG.

On 12 October 2011 the exercise drill "IOWAVE11" was carried out in the Indian Ocean. With this drill, InaTEWS successfully demonstrated that it could, furthermore, take over the role of a Regional Tsunami Service Provider (RTSP). Since then Indonesia, in addition to Australia und India, performs the double function as a National Tsunami Warning Center (NTWC) and also as a RTSP and takes over the responsibility for the timely warning of 28 states around the Indian Ocean in the event of a threatening Tsunami. With the on-going step-by-step development, a comprehensive all-encompassing InaTEWS could be successfully realized.

Indonesia now avails of one of the most modern Tsunami Early Warning Systems. On the basis of data from approx. 300 measuring stations a warning can be issued at a maximum of five minutes after an earthquake. These measuring stations include e.g. seismometers, GPS stations und coastal tide gauges. With the data gained from the sensors and using the most modern evaluation systems such as SeisComP3 which was developed by GFZ scientists for the analyses of earthquake data and a Tsunami simulation system in the Warning Centre it is possible to compile a comprehensive picture of the situation. With the aid of a decision support system respectively classified warnings for the affected coastal areas can then be issued. A total of 70 people are involved the operation of the Warning Centre in Jakarta, with 30 employees working solely in a full shift system. According to information provided by the BMKG a total of 1700 earthquakes with a magnitude of more than M= 5 and 11 quakes with a magnitude of 7 and higher have been evaluated and six Tsunami Warnings have been issued to the public by the Earthquake Monitoring and Tsunami Early Warning Centre since the hand over in March 2011.

Schooling, training and disaster precautions (capacity development) for the local community and Town and District councils have received special emphasis. This Capacity Development has been carried out since 2006 in three "typical" regions: Padang (Sumatra), Chilacap (South-Java) and Denpassar (Bali, tourist stronghold). Here particular emphasis was placed on understanding both the warnings issued and the planned evacuation measures.

Local disaster management structures are established with local decision-makers and Disaster Risk Reduction Strategies are developed. Specifically, the education of trainers who are, in turn, responsible for the further spreading of the developed concepts plays a significant role.

Another key element is the determination of hazard and risk maps as a basis for the local evacuation planning as well as for future town and land-use planning. In Bali communication with the hotel industry was an additional factor.

No Early Warning System will ever be able to prevent a strong earthquake and a resulting tsunami and also, in the future, there will be loss of life and material damage. However, through the existence of an Early Warning System and the integration of organizational measures together with comprehensive capacity building the adverse effects of such a natural disaster can certainly be reduced.

Source: Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

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Engineers to simulate, model tornado winds, their effects on buildings

Partha Sarkar designed and built the Iowa State University Tornado Simulator a decade ago. A recent grant will support new simulator studies of tornado winds and their impacts on homes and buildings. Credit: Bob Elbert

The Iowa State University Tornado Simulator kicked up a thick and slowly spinning funnel cloud over a model of a small town, overwhelming the miniature streets, buildings and homes.

Partha Sarkar turned from the laboratory vortex and announced, "That's an EF3."

Most tornadoes (about 90 percent of them) are EF3 or less in intensity. And so Sarkar advocates that homes and buildings within tornado alley across the middle of the U.S. be designed to withstand EF3 tornadoes and their top wind speeds of 165 mph.

Sarkar, an Iowa State professor of aerospace engineering, knows something about the biggest tornadoes. He walked the debris fields of Parkersburg in 2008 and Joplin, Missouri, in 2010, and has seen what the 200-plus mph winds of EF5 storms can do to cities, buildings and people.

To study the interaction of tornadoes with human-made structures, he designed and built a tornado simulator that can create and move a tornado-like vortex back and forth over a test bed. He, his coworkers and Iowa State students have worked with the simulator for a decade, studying the loads and pressures caused by laboratory storms passing over models of homes and buildings.

But, Sarkar said, there's still a lot engineers don't understand about tornado winds:

How, for example, do nearby structures and terrain affect those winds? How do building codes, building ages, structure shapes, roof types and even construction quality influence tornado damage? How do internal pressures inside buildings influence tornado damage? And, how are the wind loads distributed and shared by a building's components, such as roof sheathing, roof trusses, walls, studs and nails?

To find these answers, the National Science Foundation has awarded a pair of three-year, $250,000 collaborative research grants to Sarkar and to Texas Tech University researchers Daan Liang, an associate professor of construction engineering and engineering technology, and Xinzhong Chen, an associate professor of civil and environmental engineering.

As part of this new project, "We will try to quantify the uncertainties in estimating tornado winds and the corresponding structural damage," Sarkar said.

To do that, Sarkar said his research group will use the latest advances in tornado simulation, data acquisition and computer modeling to answer engineering questions about tornado winds and their effects on buildings.

One result of this research could be refinements to the Enhanced Fujita (EF) Scale that considers storm damage to measure the strength of tornadoes. Another result could be new provisions in building codes and construction practices for tornado-resistant buildings.

"The overarching goal of this research is to enhance society's resiliency to tornadoes through innovative design and construction of building components and systems in tornado-prone regions," the Iowa State and Texas Tech researchers wrote in a project summary.

At Iowa State, Sarkar said the grant will support experiments and data collection with the tornado simulator. One experiment, for example, will study actual buildings damaged in tornadoes by creating computer and physical models of the buildings and their structural failures. The computer models will be refined and verified by running lab tornadoes over the physical models. The computational models -- called finite element models -- will help researchers understand and predict the damage caused by tornado winds.

Data from the experiments and models will also be shared with the Texas Tech construction engineers who will study building performance in tornado winds.

"In the long run," the researchers wrote in their summary, "the research is expected to contribute to methods and strategies that can be implemented for preventing tornado hazards from becoming disasters."

Source: Iowa State University

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NASA HS3 instrument views two dimensions of clouds

The second Cloud Physics Lidar built to fly on NASA's unmanned Global Hawk aircraft. In this summer's Hurricane and Severe Storm Sentinel or HS3 mission, the CPL is studying the changing profile of the atmosphere in detail to learn more about how hurricanes form and strengthen. Credit: NASA

Looking out the window of a commercial plane during takeoff is like taking the nickel tour of the profile of the atmosphere. As the plane ascends, what may start as a gloomy day on the ground, can turn into rain streaking across the window as you pass through the white-gray cloud, and then sunny skies above once the plane reaches cruising altitude.

NASA's Cloud Physics Lidar (CPL) instrument, flying aboard an unmanned Global Hawk aircraft in this summer's Hurricane and Severe Storm Sentinel, or HS3, mission, is studying the changing profile of the atmosphere in detail to learn more about how hurricanes form and strengthen.

"CPL profiles the atmosphere to get a two-dimensional picture of cloud and aerosols, from the top down," said Matt McGill of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who led the instrument team that designed and built the CPL. Its data, presented as if it were a curtain hanging from the sky, shows what's in the atmosphere's different layers.

From about 60,000 feet on the Global Hawk, twice the altitude of a commercial plane, 94 percent of the atmosphere lies below the instrument. The lidar works by sending rapid pulses of light that, like a radar beam, bounce and scatter off any particles they encounter, such as cloud droplets or dust particles. Some of the scattered light returns to the instrument where it records how long it took for the photons to leave and return -- giving the altitude of the particles.

CPL sends out 5,000 pulses of light per second in three different wavelengths, allowing the science team to discriminate between different types of particles, McGill said. "Is it a cloud made of water? Is it a cloud made of ice or mixed [water and ice]? And we can say something about what type of airborne particle we are seeing. Is it dust or smoke or pollution?"
For the scientists studying hurricanes, those distinctions are important. One of the major areas of study is how Saharan dust off of Africa travels across the Atlantic and affects hurricane formation and intensification. CPL data have been used to verify model projections of Saharan dust in the tropics. The CPL data showed dust layers had a vertical distribution different than models predicted. Instead dust layers occupied narrower altitude ranges. The finding led to an improvement in the dust models, which then feed into hurricane models.

Situated in the nose of the Global Hawk flying over the storm environment, CPL also has a role in on-the-fly mission planning. While in flight, the CPL sends its data back to the team on the ground. "The mission scientists involved in the flight planning can sit there and watch the data with us in real time and say, 'Oh, we're not getting what we want.' Then they can go work with the flight planners and pilots to reroute the aircraft into different areas," said McGill. "They love that."

The airborne science community takes full advantage of the quick look capability, as well as the 24-hour turn around for the final data products. CPL is one of the most flown instruments in NASA's Earth science fleet. "It's a workhorse for the field campaigns," said McGill.

The original CPL was built in 1999 and took its first flight on the ER-2 high altitude research aircraft in 2000. Over the years CPL has been used as a satellite simulator for ground validation efforts, a cloud spotter for other instruments needing a clear view of the ground, as well as the main data collector for scientists studying atmospheric composition and Earth's energy budget where thin clouds and aerosols are major players. The lidar was also part of the proof of concept flights for the A-Train, a series of satellites flying in the same orbit making near-simultaneous measurements of the Earth system using many different instruments. That proof of concept airborne campaign showed scientists the power of combining multiple Earth observing data sets.

In 2007, when talk began of using Global Hawks for Earth science, CPL was among the first sensors considered; its size is perfect for the instrument compartment. Worries about the untested Global Hawk led to a second nearly identical instrument being built for use on the unmanned aircraft. It flew on NASA's maiden Global Hawk Pacific campaign in 2009. Since then, the Global Hawk CPL has flown in two multi-year campaigns, alternating between the Airborne Tropical Tropopause Experiment (ATTREX) and HS3.

Compact and fully autonomous, the CPL lidar design pioneered photon-counting technology that has led to the development of two instruments that will fly in space, the Cloud-Aerosol Transport System (CATS), which launches to the International Space Station this December, and the Advanced Topographic Laser Altimeter System (ATLAS), which will fly on the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) scheduled to launch in 2017.

The solid design of the instrument has borne up surprisingly well over the years, said McGill, who uses CPL as a learning tool for interns and young scientists getting their hands dirty in the field. Together, the twin CPL instruments have flown 26 missions. HS3 will mark the 27th overall and the seventh for the Global Hawk CPL.

"It's still going strong," McGill said.

The HS3 mission is funded by NASA Headquarters and overseen by NASA's Earth System Science Pathfinder Program at NASA's Langley Research Center in Hampton, Virginia, and is one of five large field campaigns operating under the Earth Venture program. The HS3 mission also involves collaborations with partners including the National Centers for Environmental Prediction, Naval Postgraduate School, Naval Research Laboratory, NOAA's Hurricane Research Division and Earth System Research Laboratory, Northrop Grumman Space Technology, National Center for Atmospheric Research, State University of New York at Albany, University of Maryland -- Baltimore County, University of Wisconsin and University of Utah. The HS3 mission is managed by the Earth Science Project Office at NASA's Ames Research Center in Moffett Field, California. The aircraft are maintained and based at NASA's Armstrong Flight Research Center in Edwards, California.

Source: NASA

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Exploring a large, restless volcanic field in Chile

Laguna del Maule, Chile, is at the center of a volcanic field that has erupted 36 times during the last 25,000 years, and is now experiencing significant uplift due to magma intrusion.
Credit: David Tenenbaum

If Brad Singer knew for sure what was happening three miles under an odd-shaped lake in the Andes, he might be less eager to spend a good part of his career investigating a volcanic field that has erupted 36 times during the last 25,000 years. As he leads a large scientific team exploring a region in the Andes called Laguna del Maule, Singer hopes the area remains quiet.

But the primary reason to expend so much effort on this area boils down to one fact: The rate of uplift is among the highest ever observed by satellite measurement for a volcano that is not actively erupting.

That uplift is almost definitely due to a large intrusion of magma -- molten rock -- beneath the volcanic complex. For seven years, an area larger than the city of Madison has been rising by 10 inches per year.

That rapid rise provides a major scientific opportunity: to explore a mega-volcano before it erupts. That effort, and the hazard posed by the restless magma reservoir beneath Laguna del Maule, are described in a major research article in the December issue of the Geological Society of America's GSA Today.

"We've always been looking at these mega-eruptions in the rear-view mirror," says Singer. 

"We look at the lava, dust and ash, and try to understand what happened before the eruption. Since these huge eruptions are rare, that's usually our only option. But we look at the steady uplift at Laguna del Maule, which has a history of regular eruptions, combined with changes in gravity, electrical conductivity and swarms of earthquakes, and we suspect that conditions necessary to trigger another eruption are gathering force."

Laguna del Maule looks nothing like a classic, cone-shaped volcano, since the high-intensity erosion caused by heavy rain and snow has carried most of the evidence to the nearby Pacific Ocean. But the overpowering reason for the absence of "typical volcano cones" is the nature of the molten rock underground. It's called rhyolite, and it's the most explosive type of magma on the planet.

The eruption of a rhyolite volcano is too quick and violent to build up a cone. Instead, this viscous, water-rich magma often explodes into vast quantities of ash that can form deposits hundreds of yards deep, followed by a slower flow of glassy magma that can be tens of yards tall and measure more than a mile in length.

The next eruption could be in the size range of Mount St. Helens -- or it could be vastly bigger, Singer says. "We know that over the past million years or so, several eruptions at Laguna del Maule or nearby volcanoes have been more than 100 times larger than Mount St. Helens," he says. "Those are rare, but they are possible." Such a mega-eruption could change the weather, disrupt the ecosystem and damage the economy.

Trying to anticipate what Laguna del Maule holds in store, Singer is heading a new $3 million, five-year effort sponsored by the National Science Foundation to document its behavior before an eruption. With colleagues from Chile, Argentina, Canada, Singapore, and Cornell and Georgia Tech universities, he is masterminding an effort to build a scientific model of the underground forces that could lead to eruption. "This model should capture how this system has evolved in the crust at all scales, from the microscopic to basinwide, over the last 100,000 years," Singer says. "It's like a movie from the past to the present and into the future."

Over the next five years, Singer says he and 30 colleagues will "throw everything, including the kitchen sink, at the problem -- geology, geochemistry, geochronology and geophysics -- to help measure, and then model, what's going on."

One key source of information on volcanoes is seismic waves. Ground shaking triggered by the movement of magma can signal an impending eruption. Team member Clifford Thurber, a seismologist and professor of geoscience at UW-Madison, wants to use distant earthquakes to locate the underground magma body.

As many as 50 seismometers will eventually be emplaced above and around the magma at Laguna del Maule, in the effort to create a 3-D image of Earth's crust in the area.

By tracking multiple earthquakes over several years, Thurber and his colleagues want to pinpoint the size and location of the magma body -- roughly estimated as an oval measuring five kilometers (3.1 miles) by 10 kilometers (6.2 miles).

Each seismometer will record the travel time of earthquake waves originating within a few thousand kilometers, Thurber explains. Since soft rock transmits sound less efficiently than hard rock, "we expect that waves that pass through the presumed magma body will be delayed," Thurber says. "It's very simple. It's like a CT scan, except instead of density we are looking at seismic wave velocity."

As Singer, who has been visiting Laguna del Maule since 1998, notes, "The rate of uplift -- among the highest ever observed -- has been sustained for seven years, and we have discovered a large, fluid-rich zone in the crust under the lake using electrical resistivity methods. Thus, there are not many possible explanations other than a big, active body of magma at a shallow depth."

The expanding body of magma could freeze in place -- or blow its top, he says. "One thing we know for sure is that the surface cannot continue rising indefinitely."

Source:  University of Wisconsin-Madison

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Re-thinking Southern California earthquake scenarios in Coachella Valley, San Andreas Fault

New 3D numerical modeling that captures more geometric complexity of an active fault segment in southern California than any other suggests that the overall earthquake hazard for towns on the west side of the Coachella Valley such as Palm Springs may be slightly lower than previously believed. Credit: Courtesy Google Earth and UMass Amherst

New three-dimensional (3D) numerical modeling that captures far more geometric complexity of an active fault segment in southern California than any other, suggests that the overall earthquake hazard for towns on the west side of the Coachella Valley such as Palm Springs and Palm Desert may be slightly lower than previously believed.

New simulations of deformation on three alternative fault configurations for the Coachella Valley segment of the San Andreas Fault conducted by geoscientists Michele Cooke and Laura Fattaruso of the University of Massachusetts Amherst, with Rebecca Dorsey of the University of Oregon, appear in the December issue of Geosphere.

The Coachella Valley segment is the southernmost section of the San Andreas Fault in California. It has a high likelihood for a large rupture in the near future, since it has a recurrence interval of about 180 years but has not ruptured in over 300 years, the authors point out.

The researchers acknowledge that their new modeling offers "a pretty controversial interpretation" of the data. Many geoscientists do not accept a dipping active fault geometry to the San Andreas Fault in the Coachella Valley, they say. Some argue that the data do not confirm the dipping structure. "Our contribution to this debate is that we add an uplift pattern to the data that support a dipping active fault and it rejects the other models," say Cooke and colleagues.

Their new model yields an estimated 10 percent increase in shaking overall for the Coachella segment. But for the towns to the west of the fault where most people live, it yields decreased shaking due to the dipping geometry. It yields a doubling of shaking in mostly unpopulated areas east of the fault. "This isn't a direct outcome of our work but an implication," they add.

Cooke says, "Others have used a dipping San Andreas in their models but they didn't include the degree of complexity that we did. By including the secondary faults within the Mecca Hills we more accurately capture the uplift pattern of the region."

Fattaruso adds, "Others were comparing to different data sets, such as geodesy, and since we were comparing to uplift it is important that we have this complexity." In this case, geodesy is the science of measuring and representing the Earth and its crustal motion, taking into account the competition of geological processes in 3D over time.

Most other models of deformation, stress, rupture and ground shaking have assumed that the southern San Andreas Fault is vertical, say Cooke and colleagues. However, seismic, imaging, aerial magnetometric surveys and GPS-based strain observations suggest that the fault dips 60 to 70 degrees toward the northeast, a hypothesis they set out to investigate.

Specifically, they explored three alternative geometric models of the fault's Coachella Valley segment with added complexity such as including smaller faults in the nearby Indio and Mecca Hills. "We use localized uplift patterns in the Mecca Hills to assess the most plausible geometry for the San Andreas Fault in the Coachella Valley and better understand the interplay of fault geometry and deformation," they write.

Cooke and colleagues say the fault structures in their favored model agree with distributions of local seismicity, and are consistent with geodetic observations of recent strain. "Crustal deformation models that neglect the northeast dip of the San Andreas Fault in the Coachella Valley will not replicate the ground shaking in the region and therefore inaccurately estimate seismic hazard," they note.

This work was supported by the National Science Foundation.

Source:  University of Massachusetts at Amherst

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Even in restored forests, extreme weather strongly influences wildfire's impacts

Fire Sweeps Up, South Flank, Rim Fire. Credit: Mike McMillan - USFS

The 2013 Rim Fire, the largest wildland fire ever recorded in the Sierra Nevada region, is still fresh in the minds of Californians, as is the urgent need to bring forests back to a more resilient condition. Land managers are using fire as a tool to mimic past fire conditions, restore fire-dependent forests, and reduce fuels in an effort to lessen the potential for large, high-intensity fires, like the Rim Fire. A study led by the U.S. Forest Service's Pacific Southwest Research Station (PSW) and recently published in the journal Forest Ecology and Management examined how the Rim Fire burned through forests with restored fire regimes in Yosemite National Park to determine whether they were as resistant to high-severity fire as many scientists and land managers expected.

Since the late 1960s, land managers in Yosemite National Park have used prescribed fire and let lower intensity wildland fires burn in an attempt to bring back historical fire regimes after decades of fire suppression. For this study, researchers seized a unique opportunity to study data on forest structure and fuels collected in 2009 and 2010 in Yosemite's old-growth, mixed-conifer forests that had previously burned at low to moderate severity. Using post-Rim Fire data and imagery, researchers found that areas burned on days the Rim Fire was dominated by a large pyro-convective plume -- a powerful column of smoke, gases, ash, and other debris -- burned at moderate to high severity regardless of the number of prior fires, topography, or forest conditions.

"The specific conditions leading to large plume formation are unknown, but what is clear from many observations is that these plumes are associated with extreme burning conditions," says Jamie Lydersen, PSW biological science technician and the study's lead author. "Plumes often form when atmospheric conditions are unstable, and result in erratic fire behavior driven by its own local effect on surface wind and temperatures that override the influence of more generalized climate factors measured at nearby weather stations."

When the extreme conditions caused by these plumes subsided during the Rim Fire, other factors influenced burn severity. "There was a strong influence of elapsed time since the last burn, where forests that experienced fire within the last 14 years burned mainly at low severity in the Rim Fire. Lower elevation areas and those with greater shrub cover tended to burn at higher severity," says Lydersen.

When driven by extreme weather, which often coincides with wildfires that escape initial containment efforts, fires can severely burn large swaths of forest regardless of ownership and fire history. These fires may only be controlled if more forests across the landscape have been managed for fuel reduction to allow early stage suppression before weather- and fuels-driven fire intensity makes containment impossible. Coordination of fire management activities by land management agencies across jurisdictions could favor burning under more moderate weather conditions when wildfires start and reduce the occurrences of harmful, high-intensity fires.

Source: USDA Forest Service - Pacific Southwest Research Station

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Deepwater Horizon spill: Much of the oil at bottom of the sea

Controlled burning of surface oil slicks during the Deepwater Horizon event.
Credit: David Valentine

Due to the environmental disaster's unprecedented scope, assessing the damage caused by the 2010 Deepwater Horizon spill in the Gulf of Mexico has been a challenge. One unsolved puzzle is the location of 2 million barrels of submerged oil thought to be trapped in the deep ocean.

UC Santa Barbara's David Valentine and colleagues from the Woods Hole Oceanographic Institute (WHOI) and UC Irvine have been able to describe the path the oil followed to create a footprint on the deep ocean floor. The findings appear today in the Proceedings of the National Academy of Sciences.

For this study, the scientists used data from the Natural Resource Damage Assessment process conducted by the National Oceanic and Atmospheric Administration. The United States government estimates the Macondo well's total discharge -- from the spill in April 2010 until the well was capped that July -- to be 5 million barrels.

By analyzing data from more than 3,000 samples collected at 534 locations over 12 expeditions, they identified a 1,250-square-mile patch of the deep sea floor upon which 2 to 16 percent of the discharged oil was deposited. The fallout of oil to the sea floor created thin deposits most intensive to the southwest of the Macondo well. The oil was most concentrated within the top half inch of the sea floor and was patchy even at the scale of a few feet.

The investigation focused primarily on hopane, a nonreactive hydrocarbon that served as a proxy for the discharged oil. Researchers analyzed the spatial distribution of hopane in the northern Gulf of Mexico and found it was most concentrated in a thin layer at the sea floor within 25 miles of the ruptured well, clearly implicating Deepwater Horizon as the source.

"Based on the evidence, our findings suggest that these deposits come from Macondo oil that was first suspended in the deep ocean and then settled to the sea floor without ever reaching the ocean surface," said Valentine, a professor of earth science and biology at UCSB. "The pattern is like a shadow of the tiny oil droplets that were initially trapped at ocean depths around 3,500 feet and pushed around by the deep currents. Some combination of chemistry, biology and physics ultimately caused those droplets to rain down another 1,000 feet to rest on the sea floor."

Valentine and his colleagues were able to identify hotspots of oil fallout in close proximity to damaged deep-sea corals. According to the researchers, this data supports the previously disputed finding that these corals were damaged by the Deepwater Horizon spill.

"The evidence is becoming clear that oily particles were raining down around these deep sea corals, which provides a compelling explanation for the injury they suffered," said Valentine. "The pattern of contamination we observe is fully consistent with the Deepwater Horizon event but not with natural seeps -- the suggested alternative."

While the study examined a specified area, the scientists argue that the observed oil represents a minimum value. They purport that oil deposition likely occurred outside the study area but so far has largely evaded detection because of its patchiness.

"This analysis provides us with, for the first time, some closure on the question 'Where did the oil go and how?' " said Don Rice, program director in the National Science Foundation's Division of Ocean Sciences. "It also alerts us that this knowledge remains largely provisional until we can fully account for the remaining 70 percent."

"These findings should be useful for assessing the damage caused by the Deepwater Horizon spill as well as planning future studies to further define the extent and nature of the contamination," Valentine concluded. "Our work can also help to assess the fate of reactive hydrocarbons, test models of oil's behavior in the ocean and plan for future spills."

Co-authors are G. Burch Fisher and Sarah C. Bagby, postdoctoral researchers in the Valentine Lab at UCSB; Robert K. Nelson, Christopher M. Reddy and Sean P. Sylva of WHOI; and Mary A. Woo of UC Irvine. The research was funded by the National Science Foundation.

Source:  University of California - Santa Barbara

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Source of volcanoes may be much closer than thought: Geophysicists challenge traditional theory underlying origin of mid-plate volcanoes

Traditional thought holds that hot updrafts from the Earth's core cause volcanoes, but researchers say eruptions may stem from the asthenosphere, a layer closer to the surface.
Credit: Virginia Tech

A long-held assumption about the Earth is discussed in today's edition of Science, as Don L. Anderson, an emeritus professor with the Seismological Laboratory of the California Institute of Technology, and Scott King, a professor of geophysics in the College of Science at Virginia Tech, look at how a layer beneath the Earth's crust may be responsible for volcanic eruptions.

The discovery challenges conventional thought that volcanoes are caused when plates that make up the planet's crust shift and release heat.

Instead of coming from deep within the interior of the planet, the responsibility is closer to the surface, about 80 kilometers to 200 kilometers deep -- a layer above the Earth's mantle, known as the as the asthenosphere.

"For nearly 40 years there has been a debate over a theory that volcanic island chains, such as Hawaii, have been formed by the interaction between plates at the surface and plumes of hot material that rise from the core-mantle boundary nearly 1,800 miles below the Earth's surface," King said. "Our paper shows that a hot layer beneath the plates may explain the origin of mid-plate volcanoes without resorting to deep conduits from halfway to the center of the Earth."

Traditionally, the asthenosphere has been viewed as a passive structure that separates the moving tectonic plates from the mantle.

As tectonic plates move several inches every year, the boundaries between the plates spawn most of the planet's volcanoes and earthquakes.

"As the Earth cools, the tectonic plates sink and displace warmer material deep within the interior of the Earth," explained King. "This material rises as two broad, passive updrafts that seismologists have long recognized in their imaging of the interior of the Earth."
The work of Anderson and King, however, shows that the hot, weak region beneath the plates acts as a lubricating layer, preventing the plates from dragging the material below along with them as they move.

The researchers show this lubricating layer is also the hottest part of the mantle, so there is no need for heat to be carried up to explain mid-plate volcanoes.

"We're taking the position that plate tectonics and mid-plate volcanoes are the natural results of processes in the plates and the layer beneath them," King said.

Source: Virginia Tech

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Earthquakes in the ocean: Towards a better understanding of their precursors

Published on 14 September in Nature Geoscience, the study conducted by researchers from several institutes, including IFREMER (French Research Institute for Exploitation of the Sea), CNRS and IFSTTAR, offers the first theoretical model that, based on fluid-related processes, explains the seismic precursors of an underwater earthquake. Using quantitative measurements, this innovative model established a link between observed precursors and the mainshock of an earthquake. The results open a promising avenue of research for guiding future investigations on detecting earthquakes before they strike.

A model specific to the submarine environment

The data used to construct the model presented in the article were collected from subsea observatories* deployed in the North-East Pacific fracture zones.

The researchers showed that the properties of the fluids that circulate in submarine fault zones change over time, during what is called the “seismic cycle”. This term describes the cycle during which strain accumulates along a fault until it exceeds the frictional forces that prevent the fault from slipping. An earthquake results at the moment of rupture, due to the sudden release of built-up strain. A new cycle begins with strain accumulating and continues until the next rupture occurs along the fault...

Due to their proximity to mid-ocean ridges, the fluids that circulate in the faults undergo tremendous pressure and extremely high temperatures. These fluids can reach the supercritical state. The physical properties of supercritical fluids (density, viscosity, diffusivity) are intermediate to those of liquids and gases.

The compressibility of supercritical fluid varies greatly with pressure, and, according to the study’s analysis, this change in compressibility may trigger an earthquake, occurring after a short period of foreshocks.

Seismic precursors
Seismic precursors are the early warning signs before an earthquake strikes. Many different types of earthquake precursors have been studied by the scientific community: ground movements, seismic signals, fluid or gas emissions, electrical signals, thermal signals, animal behaviour, etc.
For an event as large as an earthquake, which releases a considerable amount of energy, there must be a preparatory phase. This problem in predicting earthquakes does not lie in the absence of precursors (hindsight observations are numerous), but in the capacity to detect these forerunners before the mainshock.

The results of the model can help guide future research in the detection of seismic precursors with, ultimately, potential applications for earthquake prediction. Supercritical fluids require very specific conditions; they are also encountered on land in hydrothermal and volcanic areas, such as Iceland.

Details of the model
Under the effect of tectonic forces, two antagonistic effects are usually in play near transform faults. First, increasing shear stress tends to break rocks and weaken resistance in the transform fault. Second, decreasing pressure of the fluid contained in the fault results in an increase in the volume of the pore space between rock beds. This effect acts as a stabilising suction cup, counterbalancing the ‘weakening’ in the rock bed and delaying the triggering of an earthquake.

The efficiency of this counterbalancing mechanism depends on fluid compressibility. It is highest in the presence of fluids in the liquid state, whose low compressibility causes a dramatic decrease in fluid pressure in response to small increases in volume. Conversely, for gas-type fluids, which are highly compressible, the suction cup effect is nearly inexistent.

When a change in the ‘liquid-gas’ state of the fluid occurs during a fault slip, the counterbalancing mechanism fails, allowing a major shock to be triggered. This transition occurs over several days and has numerous signs, including many small foreshocks.

*Subsea observatories are comparable to a laboratory on the seafloor. Equipped with a series of instruments, they record many types of data that can be used to study the geophysical events that occur in the ocean.

Source: Institut français de recherche pour l'exploitation de la mer (Ifremer)

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A global surge of great earthquakes from 2004-2014 and implications for Cascadia

The last ten years have been a remarkable time for great earthquakes. Since December 2004 there have been no less than 18 quakes of Mw8.0 or greater -- a rate of more than twice that seen from 1900 to mid-2004. Hundreds of thousands of lives have been lost and massive damage has resulted from these great earthquakes. But as devastating as such events can be, these recent great quakes have come with a silver lining: They coincide with unprecedented advances in technological and scientific capacity for learning from them.

"We previously had very limited information about how ruptures grow into great earthquakes and interact with regions around them," said seismologist Thorne Lay of the University of California at Santa Cruz. "So we are using the recorded data for these recent events to guide our understanding of future earthquakes. We've gained a new level of appreciation for how one earthquake can influence events in other zones."

High on the list of areas ripe for a great quake is Cascadia, the Pacific Northwest, where the risk for great quakes had long been under appreciated. Evidence began surfacing about 20 years ago that there had been a great quake in the region in the year 1700. Since then the view of the great quake risk in Cascadia has shifted dramatically.

"We don't know many details about what happened in 1700," said Lay. There were no instruments back then to observe and record it. And so the best way to try and understand the danger and what could happen in Cascadia is to study the recent events elsewhere.

Over the last decade Lay and his colleagues have been able to gather fine details about these giant earthquakes using data from an expanded global networks of seismometers, GPS stations, tsunami gauges, and new satellite imaging capabilities such as GRACE, InSAR, and LandSAT interferometry. Among the broader conclusions they have come to is that great quakes are very complicated and idiosyncratic. Lay will be presenting some of those idiosyncrasies at the meeting of the Geological Society of America in Vancouver on Oct. 21.

"What we've seen is that we can have multiple faults activated," said Lay. "We've seen it off Sumatra and off Japan. Once earthquakes get going they can activate faulting in areas that were thought not physically feasible."

The great Sumatra-Andaman earthquake of Dec. 26, 2004, for instance, unzipped a 1,300 kilometer long segment of the subduction zone and unleashed one of history's most destructive, deadly tsunamis. Much of the rupture was along a region with very limited plate convergence. In Japan, the Kuril Islands, and the Solomon Islands, great mega-thrust ruptures have ruptured portions of the subduction zones that were thought too warm or weak to experience earthquakes.

"These earthquakes ruptured right through areas that had been considered to have low risk," said Lay. "We thought that would not happen. But it did, so we have to adjust our understanding."

Perhaps the best recent analogy to Cascadia is off the coast of Iquique, Chile, said Lay. There had been a great quake in 1877, and a conspicuous gap in quakes ever since. Like the 1700 Cascadia earthquake, there is little data for the 1877 event, which killed more than 2,500 people. In both subduction zones, the converging plates are thought to be accumulating strain which could be released in a very large and violent rupture. On April 1 of this year, some of that strain was released offshore of Iquique. There was a Mw8.1 rupture in the northern portion of the seismic gap. But it involved slip over less than 20 percent of the region that seismologists believe to have accumulated strain since 1877.

"We have no idea why only a portion of the 1877 zone ruptured," said Lay. "But clearly, 80 percent of that zone is still unruptured. We don't have a good basis for assessment of how the rest will fail. It's the same for Cascadia. We don't know if it always goes all at once or sometimes in sequences of smaller events, with alternating pattern. It is prudent to prepare for the worst case of failure of the entire region in a single event, but it may not happen that way every time."

What is certain is that studying these recent big earthquakes has given geophysicists the best information ever about how they work and point to new ways to begin understanding what could be in Cascadia's future.

Source: Geological Society of America

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Hippos-Sussita excavation: Silent evidence of the earthquake of 363 CE

The city of Hippos-Sussita, which was founded in the second century BCE, experienced two strong and well-documented earthquakes. The first was in the year 363 CE and it caused heavy damage. The city, did, however, recover. The great earthquake of 749 CE destroyed the city which was subsequently abandoned completely. Evidence of the extensive damage caused by the earthquake of 363 was found in earlier seasons. None, however, was as violent, thrilling and eerie as the evidence discovered this year. Credit: Image courtesy of University of Haifa

Silent evidence of a large earthquake in 363 CE -- the skeleton of a woman with a dove-shaped pendant was discovered under the tiles of a collapsed roof by archeologists from the University of Haifa during this excavation season at Hippos-Sussita. They also found a large muscular marble leg and artillery ammunition from some 2,000 years ago. "The data is finally beginning to form a clear historical-archaeological picture," said Dr. Michael Eisenberg, head of the international excavation team.

The past fifteen excavation seasons at Hippos-Sussita, run by archeologists from the Zinman Institute of Archaeology at the University of Haifa, have not stopped providing a constant flow of fascinating findings. The team digging at the city site -- situated east of the Sea of Galilee in the Sussita National Park, which is under the management of the Israel Nature and Parks Authority -- has grown over the years, with more and more teams and excavators from various countries joining them. This time, the security situation in the south of Israel "sent" them a Canadian team, led by Dr. Stephen Chambers, as reinforcement.

The city of Hippos-Sussita, which was founded in the second century BCE, experienced two strong and well-documented earthquakes. The first was in the year 363 CE and it caused heavy damage. The city, did, however, recover. The great earthquake of 749 CE destroyed the city which was subsequently abandoned completely. Evidence of the extensive damage caused by the earthquake of 363 was found in earlier seasons. None, however, was as violent, thrilling and eerie as the evidence discovered this year.

To the north of the basilica, the largest building in town that served as the commercial, economic and judicial center of the city, the dig's senior area supervisor Haim Shkolnik and his team unearthed the remains of several skeletons that had been crushed by the weight of the collapsed roof. Among the bones of one of the women lay a gold dove-shaped pendant.

This year, evidence was found for the first time that the great earthquake of 363 CE had destroyed the Roman bathhouse, which was uncovered by the team run by Arleta Kowalewska from Poland. Like the basilica, it too was not rebuilt. According to Dr. Eisenberg, the evidence found so far shows that the earthquake was so powerful it completely destroyed the city, which took some twenty years to be rebuilt. Among the wreckage from the bathhouse, an excellent Roman marble sculpture of a muscular right leg of a man leaning against a tree trunk was found. "It is too early to determine who the man depicted in the sculpture was. It could be the sculpture of a god or an athlete; it was more than two meters tall. We hope to find more parts of the sculpture in the coming seasons to shed some light on his identity," said Dr. Eisenberg.

Excavations were resumed in the bastion, the main defense post of the Roman period city built on the southern edge of the cliff, where the work focused on the fortified position of a projectile machine that propelled/launched ballista stones. The catapult was some eight meters long according to the size of the chamber. So far the archeologists have found a number of ballista balls that fit the massive catapult, as well as smaller balls that were used on smaller ballista machines. These machines were positioned above the bastion's vaults and were used to launch basalt ballista balls slightly smaller than soccer balls as far as 350 meters.

A section of the western part of the city's main colonnaded street, which traversed its entire length of 600 meters from east to west (the decumanus maximus) was excavated this year with the help of a Canadian team, after their planned dig in the south was cancelled. The archeologists uncovered another original piece of the wall that supported the street columns, confirming the theory that it had been a magnificent colonnaded street similar to those of the Roman East cities that were built at the peak of the Pax Romana -- the Roman era of peace during the first few centuries CE.

While working on the dig the team also invested a lot of work on the site's conservation. "I am extremely proud that we were able to organize a sizable conservation team this year as well, from our own internal budgets and with the help of the Western Galilee College in Acre. Twenty-two students from the college's Department of Conservation together with five experienced conservators under the direction of Julia Burdajewicz from the Academy of Fine Arts in Warsaw conducted the conservation work. This is one of the major tourist destinations in the northern part of the country, and as such I see this as a national mission, even if the budget comes primarily from our own sources, without government support," concluded Dr. Eisenberg.

Source: University of Haifa

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The Fukushima accident underscores need for U.S. to seek out new information about nuclear plant hazards

Fukushima accident 

A new congressionally mandated report from the National Academy of Sciences concludes that the overarching lesson learned from the 2011 Fukushima Daiichi nuclear accident is that nuclear plant licensees and their regulators must actively seek out and act on new information about hazards with the potential to affect the safety of nuclear plants. The committee that wrote the report examined the causes of the Japan accident and identified findings and recommendations for improving nuclear plant safety and offsite emergency responses to nuclear plant accidents in the U.S.

The accident at the Fukushima Daiichi plant was initiated by the Great East Japan Earthquake and tsunami on March 11, 2011. The earthquake knocked out offsite AC power to the plant, and the tsunami inundated portions of the plant site. Flooding of critical equipment resulted in the extended loss of onsite power with the consequent loss of reactor monitoring, control, and cooling functions in multiple units. Three reactors -- Units 1, 2, and 3 -- sustained severe core damage, and three reactor buildings -- Units 1, 3, and 4 -- were damaged by hydrogen explosions. Offsite releases of radioactive materials contaminated land in Fukushima and several neighboring prefectures, prompting widespread evacuations, distress among the population, large economic losses, and the eventual shutdown of all nuclear power plants in Japan.

Personnel at the Fukushima Daiichi plant responded to the accident with courage and resilience, and their actions likely reduced its severity and the magnitude of offsite radioactive material releases, the committee said. However, several factors relating to the management, design, and operation of the plant prevented plant personnel from achieving greater success and contributed to the overall severity of the accident.

Nuclear plant operators and regulators in the U.S. and other countries are taking useful actions to upgrade nuclear plant systems, operating procedures, and operator training in response to the Fukushima Daiichi accident. As the U.S. nuclear industry and its regulator, the U.S. Nuclear Regulatory Commission (USNRC), implement these actions, the report recommends particular attention to improving the availability, reliability, redundancy, and diversity of specific nuclear plant systems:

·DC power for instrumentation and safety system control

·tools for estimating real-time plant status during loss of power

·reactor heat removal, reactor depressurization, and containment venting systems and protocols

·instrumentation for monitoring critical thermodynamic parameters -- for example temperature and pressure -- in reactors, containments, and spent-fuel pools

·hydrogen monitoring, including monitoring in reactor buildings, and mitigation

·instrumentation for both onsite and offsite radiation and security monitoring

·communications and real-time information systems

To further improve the resilience of U.S. nuclear plants, the report also recommends:
·The U.S. nuclear industry and the USNRC should give specific attention to improving resource availability and operator training, including training for developing and implementing ad hoc responses to deal with unanticipated complexities.

·The U.S. nuclear industry and USNRC should strengthen their capabilities for assessing risks from events that could challenge the design of nuclear plant structures and components and lead to a loss of critical safety functions. Part of this effort should focus on events that have the potential to affect large geographic regions and multiple nuclear plants, including earthquakes, tsunamis and other geographically extensive floods, and geomagnetic disturbances. USNRC should support these efforts by providing guidance on approaches and overseeing rigorous peer review.

·USNRC should further incorporate modern risk concepts into its nuclear safety regulations using these strengthened capabilities.

·USNRC and the U.S. nuclear industry must continuously monitor and maintain a strong safety culture and should examine opportunities to increase the transparency of and communication about their efforts to assess and improve nuclear safety.

Until now, U.S. safety regulations have been based on ensuring plants are designed to withstand certain specified failures or abnormal events, or "design-basis-events"-- such as equipment failures, loss of power, and inability to cool the reactor core -- that could impair critical safety functions. However, four decades of analysis and experience have demonstrated that reactor core-damage risks are dominated by "beyond-design-basis events," the report says. The Fukushima Daiichi, Three Mile Island, and Chernobyl accidents were all initiated by beyond-design-basis events. The committee found that current approaches for regulating nuclear plant safety, which have been based traditionally on deterministic concepts such as the design-basis accident, are clearly inadequate for preventing core-melt accidents and mitigating their consequences. A more complete application of modern risk-assessment principles in licensing and regulation could help address this inadequacy and enhance the overall safety of all nuclear plants, present and future.

The Fukushima Daiichi accident raised the question of whether offsite emergency preparedness in the U.S. would be challenged if a similar-scale event -- involving several concurrent disasters -- occurred here. The committee lacked time and resources to perform an in-depth examination of U.S. preparedness for severe nuclear accidents. The report recommends that the nuclear industry and organizations with emergency management responsibilities assess their preparedness for severe nuclear accidents associated with offsite regional-scale disasters.

Emergency response plans, including plans for communicating with affected populations, should be revised or supplemented to ensure that there are scalable and effective strategies, well-trained personnel, and adequate resources for responding to long-duration accident/disaster scenarios. In addition, industry and emergency management organizations should assess the balance of protective actions -- such as evacuation, sheltering-in-place, and potassium iodide distribution -- for affected offsite populations and revise the guidelines as appropriate. Particular attention should be given to protective actions for children, those who are ill, and the elderly and their caregivers; long-term social, psychological, and economic impacts of sheltering-in-place, evacuation, and/or relocation; and decision making for resettlement of evacuated populations in areas that were contaminated by radioactive material.

Source: National Academy of Sciences

Report: http://www.nap.edu/catalog.php?record_id=18294

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The Disaster planning: Risk assessment vital to development of mitigation plans

Wildfires and flooding affect many more people in the USA than earthquakes and landslide and yet the dread, the perceived risk, of the latter two is much greater than for those hazards that are more frequent and cause greater loss of life. Research published in the International Journal of Risk Assessment and Management, suggests that a new paradigm for risk assessment is needed so that mitigation plans in the face of natural disasters can be framed appropriately by policy makers and those in the emergency services.

Maura Knutson (nee Hurley) and Ross Corotis of the University of Colorado, Boulder, explain that earlier efforts for incorporating a sociological perspective and human risk perception into hazard-mitigation plans, commonly used equivalent dollar losses from natural hazard events as the statistic by which to make decisions. Unfortunately, this fails to take into consideration how people view natural hazards, the team reports. Moreover, this can lead to a lack of public support and compliance with emergency plans when disaster strikes and lead to worse outcomes in all senses.

The researchers have therefore developed a framework that combines the usual factors for risk assessment, injuries, deaths and economic and collateral loss with the human perception of the risks associated with natural disasters. The framework includes risk perception by graphing natural hazards against "dread" and "familiarity." These two variables are well known to social psychologists as explaining the greatest variability in an individual's perception of risk, whether considering earthquakes, landslides, wildfires, storms, tornadoes, hurricanes, flooding, avalanche, even volcanic activity. "Understanding how the public perceives the risk for various natural hazards can assist decision makers in developing and communicating policy decisions," the team says.

The higher the perceived risk of a natural disaster, the more people want to see that risk reduced and that means seeing their tax dollars spent on mitigation and preparation. For example, far more money is spent on reducing earthquake risk than on reducing the risk from wildfires, perhaps because the perceived risk is much greater, even though both will cause significant losses of life and property. The team's new framework for risk assessment will act as an aid in decision making for these types of situations as well as perhaps even offering a way to give members of the public a clearer understanding of actual risk rather than perceived risk.

Source: Inderscience Publishers

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The Network for tracking earthquakes exposes glacier activity: Accidental find offers big potential for research on Alaska's glaciers

Alaska’s seismic network records thousands of quakes produced by glaciers, capturing valuable data that scientis ts could use to better understand their behavior, but instead their seismic signals are set aside as oddities. The current earthquake monitoring system could be “tweaked” to target the dynamic movement of the state’s glaciers.
Credit: Chris Larson

Alaska's seismic network records thousands of quakes produced by glaciers, capturing valuable data that scientists could use to better understand their behavior, but instead their seismic signals are set aside as oddities. The current earthquake monitoring system could be "tweaked" to target the dynamic movement of the state's glaciers, suggests State Seismologist Michael West, who will present his research today at the annual meeting of the Seismological Society of America (SSA).

"In Alaska, these glacial events have been largely treated as a curiosity, a by-product of earthquake monitoring," said West, director of the Alaska Earthquake Center, which is responsible for detecting and reporting seismic activity across Alaska.

The Alaska seismic network was upgraded in 2007-08, improving its ability to record and track glacial events. "As we look across Alaska's glacial landscape and comb through the seismic record, there are thousands of these glacial events. We see patterns in the recorded data that raise some interesting questions about the glaciers," said West.

As a glacier loses large pieces of ice on its leading edge, a process called calving, the Alaska Earthquake Center's monitoring system automatically records the event as an earthquake. Analysts filter out these signals in order to have a clear record of earthquake activity for the region. In the discarded data, West sees opportunity.

"We have amassed a large record of glacial events by accident," said West. "The seismic network can act as an objective tool for monitoring glaciers, operating 24/7 and creating a data flow that can alert us to dynamic changes in the glaciers as they are happening." It's when a glacier is perturbed or changing in some way, says West, that the scientific community can learn the most.

Since 2007, the Alaska Earthquake Center has recorded more than 2800 glacial events along 600 km of Alaska's coastal mountains. The equivalent earthquake sizes for these events range from about 1 to 3 on the local magnitude scale. While calving accounts for a significant number of the recorded quakes, each glacier's terminus -- the end of any glacier where the ice meets the ocean -- behaves differently. Seasonal variations in weather cause glaciers to move faster or slower, creating an expected seasonal cycle in seismic activity. But West and his colleagues have found surprises, too.

In mid-August 2010, the Columbia Glacier's seismic activity changed radically from being relatively quiet to noisy, producing some 400 quakes to date. These types of signals from the Columbia Glacier have been documented every single month since August 2010, about the time when the Columbia terminus became grounded on sill, stalling its multi-year retreat.

That experience highlighted for West the value of the accidental data trove collected by the Alaska Earthquake Center. "The seismic network is blind to the cause of the seismic events, cataloguing observations that can then be validated," said West, who suggests the data may add value to ongoing field studies in Alaska.

Many studies of Alaska's glaciers have focused on single glacier analyses with dedicated field campaigns over short periods of time and have not tracked the entire glacier complex over the course of years. West suggests leveraging the data stream may help the scientific community observe the entire glacier complex in action or highlight in real time where scientists could look to catch changes in a glacier.

"This is low-hanging fruit," said West of the scientific advances waiting to be gleaned from the data.

Source: Seismological Society of America

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