Promising MS drug may worsen disease, research suggests

UNIVERSITY OF VIRGINIA HEALTH SYSTEM

Research News

 

IMAGE: ALBAN GAULTIER, PHD, OF THE UNIVERSITY OF VIRGINIA SCHOOL OF MEDICINE, HAS CONCLUDED THAT A PROMISING MS DRUG MAY WORSEN THE DISEASE IN PEOPLE. view more 

CREDIT: DAN ADDISON | UVA COMMUNICATIONS

A drug that has shown promise for treating multiple sclerosis may actually make the debilitating disease worse, new research from the University of Virginia School of Medicine suggests.

The drug has not yet made it to human trials for MS, but the UVA scientists are warning their fellow researchers to proceed extremely cautiously. In addition to worsening the disease in mouse models, the drug also had unintended, off-target effects, they report.

"It was not at all what we expected," said MS researcher Alban Gaultier, PhD, of UVA's Department of Neuroscience and its Center for Brain Immunology and Glia (BIG). "The take-home message is that we should be very careful and do more fundamental research before we propose to take this to clinical trials."

About Multiple Sclerosis

Multiple sclerosis is a debilitating autoimmune disease that affects an estimated 1 million Americans. The disease causes the body's immune system to destroy myelin, the insulation that surrounds and protects our nerve fibers. This prevents the nerves from transmitting signals to the brain. The damage can create a wide range of symptoms, including muscle spasms, fatigue, difficulty moving, numbness and pain. These symptoms can vary from patient to patient.

Existing MS drugs carry unwanted side effects, such as impairing the body's ability to fight infections, so doctors are eager to develop better alternatives. One promising candidate is a small-molecule drug called TEPP-46. Originally developed to fight cancer, TEPP-46 targets what is known as "metabolic adaptation" - changes in how cells generate energy - that occurs in both cancer and MS.

In Gaultier's MS models, however, TEPP-46 worsened the disease, redirecting inflammation from the spinal cord into the brain. He and his collaborators determined the drug caused harmful changes in immune cells called T cells, though he and his team do not fully understand why. There were also unexpected "off-target" effects, meaning the drug affected other cellular processes than the one intended.

Gaultier notes his findings are at odds with other studies, and he says more research is needed before scientists move the drug into clinical trials in people with MS.

One upside to the new research is that it suggests that TEPP-46 could be used to create better mouse models of MS, helping scientists in their efforts to understand and treat the disease.

"It's something that could be very useful," Gaultier said. "In this animal model of MS, most of the inflammation takes places in the spinal cord. So by using that drug and reprogramming the immune cells, we were able to move the pathology from the spinal cord to the brain, which better mimics human disease."

Findings Published

The researchers have published their findings in the scientific journal Science Signaling. The research team consisted of Scott M. Seki, Kacper Posyniak, Rebecca McCloud, Dorian A Rosen, Anthony Ferna?ndez-Castan?eda, Rebecca M. Beiter, Vlad Serbulea, Sarah C. Nanziri, Nikolas Hayes, Charles Spivey, Lelisa Gemta, Timothy Bullock, Ku-Lung Hsu and Gaultier.

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The research was supported by the Owens Family Foundation and the National Institutes of Health (NIH grants R01 NS083542, R33 MH108156, T32 GM008328, T32 GM007055, T32 GM007267, F31 NS103327 and NSF2018255830).

To keep up with the latest medical research news from UVA, subscribe to the Making of Medicine blog at http://makingofmedicine.virginia.edu.

Hydroxychloroquine 

does not help patients 

hospitalized with 

COVID-19: Study

VANDERBILT UNIVERSITY MEDICAL CENTER

Research News

 

Findings from a national study published today in the Journal of the American Medical Association (JAMA) "do not support" the use of hydroxychloroquine for the treatment of adult patients hospitalized with COVID-19.

The Outcomes Related to COVID-19 treated with Hydroxychloroquine among In-patients with symptomatic Disease (ORCHID) study found that, when compared to inactive placebo, hydroxychloroquine did not significantly improve clinical outcomes of patients hospitalized for respiratory illness related to COVID-19.

The study, which was funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health, was conducted at 34 hospitals in the Prevention and Early Treatment of Acute Lung Injury (PETAL) Clinical Trials Network.

"Hydroxychloroquine became a very commonly used medication for COVID-19 in the spring of 2020 without strong evidence that it would be beneficial," said the study's lead investigator, Wesley H. Self, MD, MPH, an emergency medicine physician and vice president for Clinical Research Networks and Strategy at Vanderbilt University Medical Center.

"Therefore, we conducted a clinical trial with the strongest methods possible to provide high quality information on whether hospitalized patients with COVID-19 should be treated with hydroxychloroquine," Self said. "Combined with other studies that showed similar findings, we believe this trial provides compelling data for clinicians to stop using hydroxychloroquine for hospitalized adults with COVID-19."

Some laboratory studies suggested hydroxychloroquine can inhibit replication of SARS-CoV-2, the virus that causes COVID-19. Observational studies early in the COVID-19 pandemic suggested that the drug may have beneficial effects for patients with COVID-19, which sparked great enthusiasm for hydroxychloroquine as a potential treatment.

However, clinical trials, which are considered the highest quality research studies for understanding the effect of a drug in patients, have failed to show beneficial effects of hydroxychloroquine for patients with COVID-19, Self said.

Between April and June 2020, 479 patients hospitalized for respiratory illness from COVID-19 were enrolled in the ORCHID study, a blinded, placebo-controlled randomized clinical trial.

Patients who were acutely ill and hospitalized with COVID-19 were treated with 10 doses of hydroxychloroquine or placebo over five days. The patient's clinical status, including hospital discharge, oxygen use, mechanical ventilator use and death, was followed for a month after the medication was started.

The study showed no evidence that hydroxychloroquine prevented death or helped patients recover from COVID-19 more quickly. One month after starting the study, 10.4% of patients treated with hydroxychloroquine and 10.6% of patients treated with placebo had died.

In June the NHLBI halted the study after determining that hydroxychloroquine was not likely to be of benefit to hospitalized patients with COVID-19.

"Our diverse teams of clinicians and research staff worked nimbly under extremely difficult circumstances to accomplish what the NIH and the PETAL Network do best: 'gold standard' studies of important questions for patients suffering from life-threatening conditions," said Samuel M. Brown, MD, MS, a critical care physician at Intermountain Healthcare and PETAL Network investigator who helped lead the trial.

"While we hoped that hydroxychloroquine would help, even this clearly negative result is critical as we work together to find effective treatments for COVID-19," Brown said.

"Having a rigorously designed clinical trial that captured patient-centered, clinically meaningful outcomes was critical to reaching the unequivocal conclusions about the use of hydroxychloroquine in COVID-19," said James P. Kiley, PhD, director, Division of Lung Diseases at NHLBI.

"ORCHID shows that hydroxychloroquine does not improve clinical outcomes in hospitalized COVID-19 patients," Kiley said. "We hope this clear result will help practitioners make informed treatment decisions and researchers continue their efforts pursuing other possible safe and effective treatments for patients suffering with this disease."

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Wolves alter wetland creation and recolonization by killing ecosystem engineers

UNIVERSITY OF MINNESOTA

Research News

 

Beavers are some of the world's most prolific ecosystem engineers, creating, maintaining and radically altering wetlands almost everywhere they live. But what, if anything, might control this engineering by beavers and influence the formation of North America's wetlands?

In a paper to be published Friday in the journal Science Advances, researchers with the University of Minnesota's Voyageurs Wolf Project and Voyageurs National Park observed and demonstrated that wolves affect wetland ecosystems by killing beavers leaving their colonies to create new ponds.

Beavers are important ecosystem engineers that create wetlands around the world, storing water and creating habitat for numerous other species. This study documents that wolves alter wetland creation when they kill beavers that have left home and created their own dams and ponds.

Juvenile beavers disperse alone and often create new ponds or fix up and recolonize existing, old ponds. By studying pond creation and recolonization patterns along with wolf predation on beavers, project biologists and co-authors Tom Gable and Austin Homkes found that 84% of newly-created and recolonized beaver ponds remained occupied by beavers for more than one year. But when a wolf kills the beaver that settles in a pond, no such ponds remain active.

This relationship between wolves and dispersing beavers shows how wolves are intimately connected to wetland creation across the boreal ecosystem and all the ecological processes that come from wetlands.

"How large predators impact ecosystems has been a matter of interest among scientists and the public for decades," said Gable, project lead of the Voyageurs Wolf Project. "Because wolves are the apex predators in northern Minnesota and beavers are ecosystem engineers, we knew there was potential for wolves to affect ecosystems by killing beavers."

Researchers found that wolves can have this impact on wetlands without necessarily changing the abundance or behavior of beavers. This newly supported link between wolf predation, dispersing beavers and wetlands may have long-lasting impacts for boreal landscapes and habitat for other species. The Voyageurs Wolf Project is investigating the long-term effects of this relationship.

"In 2015, we documented a wolf killing a dispersing beaver in a newly-created pond," said Homkes, a field biologist with the Voyageurs Wolf Project. "Within days of the wolf killing the beaver, the dam failed because there was no beaver left to maintain it. The wolf appeared to have prevented the beaver from turning this forested area into a pond. This initial observation was fascinating and we realized we needed to figure out how wolves were connected to wetland creation in the Greater Voyageurs Ecosystem."

After five years of intensive fieldwork, Gable, Homkes and colleagues have estimated that wolves altered the establishment of about 88 ponds per year and the storage of over 51 million gallons of water annually in the Greater Voyageurs Ecosystem. The pond observed in 2015 still has not been colonized by another beaver, said Gable, who visited the site in mid-September 2020.

"Our work hints at the possibility that wolves might have a longer-term impact on wetland creation and generate habitat patchiness that supports many other species across the landscape, but we need to study this mechanism further," said Joseph Bump, co-author and associate professor in the University's Department of Fisheries, Wildlife, and Conservation Biology.

Wolves and large predators are usually thought to have outsized ecological effects primarily by reducing the abundance of their prey or by altering the behavior of their prey through fear of predation, both of which allow predators to indirectly impact lower parts of the food chain such as vegetation, songbirds and other wildlife. Some research has even claimed wolves impact river ecosystems through trophic cascades, but this has been met with substantial skepticism and remains hotly debated among scientists.

"The fact that we have convincingly shown wolves can impact wetlands without necessarily changing the abundance or behavior of beavers is a really exciting finding," said co-author Sean Johnson-Bice, a project collaborator from the University of Manitoba.

"The Greater Voyageurs Ecosystem sits within a flat landscape that is dominated by water and trees, creating the perfect conditions that currently support some of the highest beaver densities in North America," said Voyageurs National Park wildlife researcher and co-author Steve Windels.

"Though we don't have evidence that wolves are limiting the size of the beaver population in Voyageurs, understanding the nuanced and complex ways that predators and prey affect one another and their environment is critical to fulfilling the National Park Service's mission to protect and preserve our resources for future generations."

This study identified a novel and unique way by which predators influence ecological processes, which ultimately enriches our understanding of the diverse roles predators play in ecosystems.

"There are a number of good reasons to maintain and restore healthy predator populations and this study should be helpful for understanding the full role and therefore value of predators, especially when they eat ecosystem engineers," Bump said.

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What does the fox say to a puma?

VIRGINIA TECH

Research News

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IMAGE: PUMAS ARE THE TOP PREDATORS IN THE STUDY RESEARCH AREA IN THE CHILEAN ANDES. CAMERA TRAP PHOTO BY CHRISTIAN OSORIO. view more 

CREDIT: CHRISTIAN OSORIO

In the high plains of the central Chilean Andes, an ecosystem consisting of only a few animal species is providing researchers with new insights into how predators coexist in the wild.

"The puma and the culpeo fox are the only top predators on the landscape in the Chilean Andes," said Professor Marcella Kelly, of the College of Natural Resources and Environment. "And there isn't a wide range of prey species, in part because the guanacos [closely related to llamas] aren't typically found in these areas anymore due to over-hunting. With such a simplified ecosystem, we thought we could really nail down how two rival predators interact."

Kelly worked with Christian Osorio, a doctoral student in the Department of Fish and Wildlife Conservation, and researchers from the Pontifical Catholic University of Chile to chart the locations of and potential interactions between pumas and foxes in central Chile. They focused on three axes of interaction: spatial (where the animals are on the landscape), temporal (the timing of specific activities on a given landscape), and dietary (what each species is eating).

To understand the interplay between pumas and foxes, researchers deployed 50 camera stations across two sites in central Chile, one in the Rio Los Cipreses National Reserve and another on private land where cattle and horses are raised. They also collected scat samples at both locations to analyze the diets of pumas and foxes.

The team's findings, published in the journal Diversity, showed that while pumas and foxes overlapped significantly where they lived and what time they were active, there was little overlap in what they were eating, with the puma diet consisting primarily of a large hare species introduced from Europe, while the culpeo foxes favored smaller rabbits, rodents, and seeds. The two predator species can successfully share a landscape and hunt for food over the same nighttime hours because they are, in essence, ordering from different menus.

"It is likely that foxes have realized that when they try to hunt hares, they might run into trouble with pumas," Osorio explained. "If they are hunting smaller mammals, the pumas don't care, but if the foxes start targeting larger prey, the pumas will react."

How predator species interact is a crucial question for ecologists trying to understand the dynamics that inform ecosystem balances. And while the puma has been designated a species of least concern, the animal's populations are declining and continue to be monitored by conservationists.

"Least concern does not mean no concern," Osorio noted. "We have laws in Chile that protect the species, but the data we have to make a conservation designation are very scattered. As we accumulate more consistent and reliable data, the puma may be reclassified as vulnerable or even endangered."

The hares that comprise approximately 70 percent of the biomass in the puma's diet are a nonnative species, introduced to the area by European settlers. With guanacos absent from the landscape, the puma has had to adapt its diet to survive.

With some land managers and conservationists campaigning for the removal of the introduced hare species as a way to restore the area's native ecosystem, Kelly and Osorio note that it is important to understand that pumas would be significantly impacted by a reduction in their primary food source.

A further concern, which the two are currently researching, is the interplay between wildlife and humans. The national reserve increasingly sees visitors eager to witness big cats and foxes in their natural environment, while the sheep and cattle industries are increasingly using remote terrain for livestock cultivation.

"Pumas do occasionally kill livestock, which is a challenge we're looking into right now," said Kelly, an affiliate of Virginia Tech's Fralin Life Sciences Institute. "The government would like to preserve the puma, but there are competing challenges of what kind of threat they pose to livestock and what kind of threat cattle or sheep farming poses to them."

Understanding how two predatory species can come to coexist has the potential to provide conservationists and ecologists with better ideas for how humans and wild animals can share a landscape.

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--Written by David Fleming

Pumas have an obsession...for Calvin Klein

Along with the traditional lures of wildcat bait and urine to draw pumas to cameras, researchers utilized an unlikely product: Calvin Klein's Obsession for Men cologne. "For some reason, pumas are particularly drawn to that scent," Kelly said. Anyone going for a hike in the high Andes might want to pass on wearing strong fragrances before heading out.

Aurora-chasing citizen scientists help discover a new feature of STEVE

NASA/GODDARD SPACE FLIGHT CENTER

Research News

 

IMAGE: TAKEN JULY 17, 2018, AT LITTLE KENOSEE LAKE, SASKATCHEWAN, CANADA, THIS PHOTO SHOWS THE TINY GREEN STREAKS BELOW STEVE. NEIL ZELLER, PHOTOGRAPHER AND CO-AUTHOR ON THE PAPER, COMMENTED "STEVE WAS... view more 

CREDIT: COPYRIGHT NEIL ZELLER, USED WITH PERMISSION

In 2018, a new aurora-like discovery struck the world. From 2015 to 2016, citizen scientists reported 30 instances of a purple ribbon in the sky, with a green picket fence structure underneath. Now named STEVE, or Strong Thermal Emission Velocity Enhancement, this phenomenon is still new to scientists, who are working to understand all its details. What they do know is that STEVE is not a normal aurora - some think maybe it's not an aurora at all - and a new finding about the formation of streaks within the structure brings scientists one step closer to solving the mystery.

"Often in physics, we build our understanding then test the extreme cases or test the cases in a different environment," Elizabeth MacDonald, a space scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, explains. "STEVE is different than the usual aurora, but it is made of light and it is driven by the auroral system. In finding these tiny little streaks, we may be learning something fundamentally new in how green auroral light can be produced."

These "tiny little streaks" are extraordinarily small point-like features within the green picket fence of STEVE. In a new paper for AGU Advances, researchers share their latest findings on these points. They suggest the streaks could be moving points of light - elongated in the images due to blur from the cameras. The tip of the streak in one image will line up with the end of the tail in the next image, contributing to this speculation from the scientists. However, there are still a lot of questions to be answered - determining whether the green light is a point or indeed a line, is one extra clue to help scientists figure out what causes green light.

"I'm not entirely sure about anything with respect to this phenomenon just yet," Joshua Semeter, a professor at Boston University and first author on the paper, said. "You have other sequences where it looks like there is a tube-shaped structure that persists from image to image and doesn't seem to conform to a moving point source, so we're not really sure about that yet."

STEVE as a whole is something that scientists are still working to label. Scientists tend to classify optical features in the sky into two categories: airglow and aurora. When airglow occurs at night, atoms in the atmosphere recombine and release some of their stored energy in the form of light, creating bright swaths of color. By studying the patterns in airglow, scientists can learn more about that area of the atmosphere, the ionosphere. To be classified as an aurora, on the other hand, that release of light must be caused by electron bombardment. These features are formed differently but also look different - airglow can occur across Earth, while auroras form in a broad ring around Earth's magnetic poles.

"STEVE in general appears to not conform well to either one of those categories," Semeter said. "The emissions are coming from mechanisms that we don't fully understand just yet."

STEVE's purple emissions are likely a result of ions moving at a supersonic speed. The green emissions seem to be related to eddies, like the ones you might see forming in a river, moving more slowly than the other water around it. The green features are also moving more slowly than the structures in the purple emissions, and scientists speculate they could be caused by turbulence in the space particles - a brew of charged particles and magnetic field, called plasma - at these altitudes.

"We know this kind of turbulence occurs. There are people who base their entire careers on studying turbulence in the ionospheric plasma formed by very rapid flows." Semeter said. "The evidence generally comes from radar measurements. We don't ever have an optical signature." Semeter suggests that when it comes to the appearance of STEVE, the flows in these instances are so extreme, that we can actually see them in the atmosphere.

"This paper is the tip of the iceberg in this new area of these tiny little pieces of the picket fence. Something we do in physics is try to chip away to increase our understanding," MacDonald said. "This paper establishes the altitude range and some of the techniques we can use to identify these features, then they can be better resolved in other observations."

To establish the altitude range and identify these features, the scientists extensively used photos and videos captured by citizen scientists.

"Citizen scientists are the ones who brought the STEVE phenomenon to the scientists' attention. Their photos are typically longer time lapse than our traditional scientific observations," MacDonald said. "Citizen scientists don't get into the patterns that scientists get into. They do things differently. They are free to move the camera around and take whatever exposure they want." However, to make this new discovery of the points within STEVE, photographers actually took shorter exposure photographs to capture this movement.

To get those photographs, citizen scientists spend hours in the freezing cold, late at night, waiting for an aurora - or hopefully STEVE - to appear. While data can indicate if an aurora will show up, indicators for STEVE haven't been identified yet. However, the aurora chasers show up and take pictures anyway.

Neil Zeller, a photographer and co-author on the paper, says he didn't originally plan to be a citizen scientist. "It was just for the beauty of it," Zeller explained. Zeller has been involved with the discovery of STEVE from the start. He showed a picture he took of STEVE to MacDonald years ago, sparking the first research into the phenomena. Now he's a co-author on this paper.

"It's an honor, it really is," Zeller said about contributing to this research. "I tend to take a step back from the scientists doing the work. I'm out there for the beauty of it and to capture these phenomena in the sky."

This paper also made use of another valuable citizen scientist contribution - a volunteer database of STEVE observations. Michael Hunnekuhl, another author on the paper, maintains this database and has contributed to STEVE findings in the past. Hunnekuhl noticed the streaks in the photographs independently of the scientists on the paper, and his detailed record and triangulation techniques were pivotal in this research.

Zeller and other citizen scientists plan to keep taking and examining those pictures, capturing the beauty of Earth's atmosphere, and MacDonald, Semeter, and other scientists will keep studying them, uncovering more about this new phenomenon.

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Retreating glacier presents landslide threat, tsunami risk in Alaskan fjord

NASA/GODDARD SPACE FLIGHT CENTER

Research News

 

IMAGE: THE UNSTABLE TERRAIN THAT POSES A LANDSLIDE THREAT LIES BETWEEN THE CASCADE GLACIER AND BARRY ARM GLACIER, WHICH HAS BEEN STEADILY RETREATING OVER THE LAST DECADE. THIS SATELLITE IMAGE SHOWS... view more 

CREDIT: NASA EARTH OBSERVATORY IMAGES BY LAUREN DAUPHIN, USING LANDSAT DATA FROM THE U.S. GEOLOGICAL SURVEY

Using NASA satellite imagery and software processing approaches, a group of geoscientists has discovered a landslide-generated tsunami threat in Barry Arm, Alaska, that will likely affect tourists and locals in the surrounding area in the next 20 years.

The Barry Arm Glacier has diminished rapidly in the last decade due to climate change, causing the surrounding terrain to become unstable. The researchers found that the mountainside near the Barry Arm Glacier has moved 394 feet (120 meters) over the seven-year period between 2010 to 2017. If that slow-moving landmass were to catastrophically fail - becoming what we typically think of as a landslide - it would fall 3,000 feet into the fjord below, sending tsunami waves toward nearby communities.

The researchers jumped into action after the discovery, writing an open letter to community stakeholders. The findings were published Oct. 29 in Geophysical Research Letters.

Chunli Dai, geophysics researcher at The Ohio State University in Columbus, worked with Bretwood Higman, geologist and co-founder of Ground Truth Alaska nonprofit, to analyze the slow-moving landslide near the Barry Arm Glacier. Their team tracked the landslide's horizontal movement using satellite imagery and measurements from NASA-U.S. Geological Survey's Landsat constellation, NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), ESA's (the European Space Agency) Sentinel-1, Planet Labs, and DigitalGlobe. As the longest-running Earth-observing satellite program, Landsat provided the researchers with an archive of satellite imagery that allowed the team to see how the Arctic surface in that area has changed over time. Data from the Polar Geospatial Center's ArcticDEM project were also used to measure the elevation of the glacier to see how its height has changed over the years.

Dai and her team developed new and innovative tools that confirmed the threat from the landslide near the Barry Arm Glacier. The tools are sensitive enough to enable the team to detect signals associated with volcanic eruptions, changes in the surface due to permafrost melting, and landslides. These tools sort through massive topographic datasets to detect subtle changes in the land's surface over time - acting as one step toward better preparation for hazards on the changing Arctic.

The new finding came out of a large project studying the topography of the Arctic surface and how that landscape is changing. The project uses ArcticDEM digital elevation models and is funded by the NASA Earth Surface and Interior (ESI) program. This project intends to use global, high-resolution topographic measurements so that NASA may better understand natural hazards and changing environments, said Benjamin Phillips, lead for NASA's Earth Surface and Interior Focus Area. Partnering with the National Science Foundation, National Geospatial-Intelligence Agency, and others, NASA supports the development and distribution of new digital surface models of the globe, constructed from optical imagery acquired by the DigitalGlobe constellation.

As the Barry Arm Glacier retreats, 600 million cubic yards of rugged terrain that was once supported by the glacier is left unstable. During a landslide, rocks and debris act less like a collection of solids and more like a fluid. In the case of sudden landslide failure, this flow of rock and debris would likely fill the fjord, leaving several smaller lakes in place of the 450-foot deep body of water.

Barry Arm Fjord and the adjacent Harriman Fjord - 60 miles east of Anchorage on the southern coast of Alaska - are frequented by cruise ships, tour boats, fishing boats, kayakers, and hikers. Because of the immediate dangers posed by the potential the landslide and tsunami threat, Dai and the other scientists signed an open letter to local community stakeholders as soon as the hazard was identified so that they were aware of the implications that the landslide would likely generate a tsunami.

At the landslide's current elevation, its mass would trigger a tsunami with waves hundreds of feet tall in Barry Arm. Broader impacts of the tsunami include 30-foot waves hitting Whittier, Alaska. Prince William Sound may experience wave and current changes, and rock and debris from the landslide would be scattered in this area.

If the landslide were to fail all at once, the potential energy stored within the event is equivalent to a magnitude seven earthquake, nearly ten times greater than any of Alaska's largest tsunami-generating landslides in the last 70 years, said geoscientist Anna Liljedahl of Woods Hole Research Center in Homer, Alaska.

The resulting tsunami could travel up the opposite side of the fjord, harming wildlife, hikers and vegetation. Farther away from the source, bays throughout Prince William Sound act as amplifiers, meaning this tsunami would be less localized and more powerful even tens of miles from the source.

As a result of this discovery, the National Oceanic and Atmospheric Administration (NOAA), the agency responsible for tsunami alerts, is in the process of preliminary tsunami modeling. In early June, NOAA also assessed the fjord for wave height monitoring equipment, which could be installed and connected to their warning system network later this summer, said Liljedahl, who worked with Dai to assess the Barry Arm landslide threat.

Alaska's Division of Geological and Geophysical Surveys (DGGS) is also monitoring the Barry Arm region following the scientists' discovery. They completed an airborne lidar survey in mid-June to track the slide's movement and are working with the Alaska Earthquake Center to install a seismic station near the fjord that will help detect sudden landslide movements. Without new monitoring equipment, Whittier would only have 20 minutes warning to evacuate if the Barry Arm landslide were to suddenly fail.

"There are a lot of natural hazards that people in Alaska are used to - earthquakes, volcanoes, and fire hazards. We need to take that mindset and apply that to landslide-generated tsunamis," Liljedahl said.

In addition to current monitoring efforts, geoscientist Bretwood Higman said that having a GPS system on the landslide mass should be a high priority because it could give a better indication as to when the landslide will fail.

"Landslides sometimes accelerate just before they fail," he said. "If you have some way of measuring deformation - if we see something like that - we can say risk is much higher right now, let's get everyone out of the area."

The landslide's movement down the mountainside is strongly correlated to the nearby Barry Arm Glacier's retreat, as surrounding area becomes destabilized as the glacier melts. While a landslide-generated tsunami is not a certainty, knowledge of the risk informs the need to monitor and prepare for the possibility. "This is such a huge area and rare event, but the risk of it happening is just going up because we have this warming climate," Liljedahl said.

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Love waves from the ocean floor

Stanford study identifies the undersea origins of mysterious love waves, decoding some of Earth's continuous vibrations

STANFORD UNIVERSITY

Research News

 

Vibrations travel through our planet in waves, like chords ringing out from a strummed guitar. Earthquakes, volcanoes and the bustle of human activity excite some of these seismic waves. Many more reverberate from wind-driven ocean storms.

As storms churn the world's seas, wind-whipped waves at the surface interact in a unique way that produces piston-like thumps of pressure on the seafloor, generating a stream of faint tremors that undulate through Earth to every corner of the globe.

"There is an imprint of those three Earth systems in this ambient seismic data: atmosphere, Earth's rocky outer layers and ocean," said Stanford University geophysicist Lucia Gualtieri, lead author of a paper in Proceedings of the National Academy of Sciences that helps to resolve a decades-old conundrum over the physics of seismic waves related to ocean storms.

Known as secondary microseisms, the small seismic waves excited by rumbling oceans are so ubiquitous and chaotic that seismologists have long set the data aside. "When you record these waves, the seismic record looks like random noise because there are so many sources, one close to the other across the extended area of a storm. They're all acting at the same time, and the resulting wavefields interfere with each other," Gualtieri said. "You want to just discard it."

Yet over the last 15 years, researchers have found a way to extract meaning from this noisy data. By analyzing how quickly pairs of waves travel from one seismic station to another, they have begun to glean insights about the materials they're moving through. "We use seismic waves like X-rays in medical imaging for scanning the Earth," said Gualtieri, who is an assistant professor of geophysics in Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth).

Love waves from the ocean floor

Unlike a single ocean wave rolling across the surface, which dies out before it reaches the deep sea, the chaotic interactions of waves traveling in opposite directions during a storm can create an up-and-down bobbing motion at the surface that pulses all the way to the solid Earth below. Vibrations known as Rayleigh waves then travel outward from the pulse, moving the ground up and down as they go.

For decades, scientists have understood the vertical component of ocean-storm microseisms, where Rayleigh waves dominate. But there is another set of vibrations recorded during ocean storms that are inexplicable in the accepted theories for how stormy seas generate movements in the solid Earth. These vibrations, named Love waves after their 20th-century discoverer, jostle underground rock particles side to side - perpendicular to their path forward - like a slithering snake. "These waves shouldn't be there at all," Gualtieri said. "We didn't know where they were coming from."

Scientists have presented two plausible explanations. One idea is that when the vertical force pumping down from colliding ocean waves encounters a slope on the seafloor, it splits and forms the two different surface wave types: Rayleigh and Love. "In that case, the source of Love waves would be very close to the source of Rayleigh waves, if not the same location," Gualtieri said.

But Gualtieri's research, co-authored with geoscientists from Princeton University, finds the slopes and inclines of the seafloor are not steep enough to generate the strong horizontal force necessary to produce the Love waves picked up by seismic recorders. Their results, published Nov. 9, support an alternative theory, in which Love waves originate within the Earth itself. It turns out that when windswept seas throttle pressure down to the seafloor, the patchwork structure of the solid Earth underneath answers with a thrum all its own.

"We understand how earthquakes create Love waves, but we've never exactly figured out how ocean waves create them," said ambient seismic noise expert Keith Koper, a professor of geology and geophysics and director of seismograph stations at the University of Utah, who was not involved with the study. "This is a little embarrassing because ocean-generated Love waves have been observed for over 50 years." The paper led by Gualtieri, he said, "provides conclusive evidence" for how ocean waves generate this particular kind of vibration in the Earth.

Simulating Earth

Using the Summit supercomputer at Oak Ridge National Laboratory, the researchers simulated the complex interactions that occur between storms, ocean waves and the solid Earth over three-hour periods. Accurate down to four seconds, each simulation included 230,400 pressure sources scattered across the entire globe. "We're using the computer as a lab, to let seismic waves propagate from realistic sources all over the world's oceans based on known physics about how and where seismic waves are generated by ocean storms, as well as how they move through the Earth," Gualtieri said.

One version of the model Earth represented the planet as a simplistic stratified world, where properties vary only with depth, like a layer cake. The other, more true-to-life model captured more of the three-dimensional variation in its underground terrain, like a chocolate chip cookie. For each version, the researchers switched underwater depth data on and off to test whether seafloor features like canyons, ravines and mountains - as opposed to the deeper structure - could produce Love waves.

The results show that Love waves are poorly generated in the layer-cake-like, one-dimensional Earth. Given about 30 minutes and a rumbling ocean, however, Love waves emanated from below the seafloor in the three-dimensional model. When Rayleigh waves and other seismic waves generated by ocean storms encounter hotter or cooler zones and different materials in their lateral journey through Earth, the study suggests their energy scatters and refocuses. In the process, a portion of the wavefield converts to Love waves. "If you apply those pressure sources from interfering ocean waves and you wait, the Earth will give you the entire wavefield," Gualtieri said. "It's the Earth itself that will generate the Love waves."

According to Gualtieri, better understanding of how these vibrations arise and propagate through Earth could help to fill in gaps in knowledge of not only our planet's interior but also its changing climate. Analog seismic recordings date back to before the satellite era, and high-quality digital data has been logged for several decades.

"This database holds information about environmental processes, and it's virtually untapped," she said.

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Computational resources were provided by the U.S. Department of Energy's Oak Ridge Leadership Computing Facility and the Princeton Institute for Computational Science & Engineering (PICSciE).

What type of forest to choose for better CO2 storage?

Forests help mitigate carbon dioxide emissions by capturing it; to make the most of this natural phenomenon, scientists have defined which types of forests can store the most carbon and under what conditions

UNIVERSITÉ DE GENÈVE

Research News

 

IMAGE: SPECIES DIVERSITY ALLOWS GREAT CARBON STORAGE ONLY IN EQUATORIAL AND TROPICAL RAIN FORESTS, SUCH AS NORTHERN CHILEAN PATAGONIA FOREST ILLUSTRATED HERE. view more 

CREDIT: © UNIGE/ MADRIGAL-GONZALEZ

An international team led by the University of Geneva (UNIGE) has studied which types of forest, in terms of biodiversity, are the most effective in storing carbon. Inventory data from natural forests on five continents show that species diversity is optimal for equatorial and tropical rainforests, and that, conversely, in forests located in cold or dry regions, it is the abundance of trees and not their diversity that favours the recapture of CO2. The results of the study, published in Nature Communications, are valuable in defining natural strategies to combat climate change. Global warming is stressing forests through higher mean annual temperatures, longer-lasting droughts and more frequent and extreme weather events. At the same time, forests - and the wood they produce - can trap and store carbon dioxide (CO2), they therefore play a crucial role in mitigating climate change. Trees and forests remove carbon dioxide from the atmosphere and convert it to carbon during photosynthesis, which they then store in the form of wood and vegetation, a process referred to as «carbon sequestration». However, not all forests have the same capacity to capture and store carbon.

Opposite Assumptions

In recent decades, researchers have suggested that species diversity allows for denser stacking and niche compartmentalisation that promotes the abundance of trees within a forest and that this abundance increases the forest's carbon storage capacity. But another hypothesis suggests that it is not diversity that allows tree abundance but the availability of energy substrate. Areas with higher energy content allows more trees to thrive per unit area and thus increase carbon recapture. While these two hypotheses question the scientific community on the relationship between diversity and abundance, knowing the answer could pragmatically guide the fight against CO2 emissions. An international team around Jaime Madrigal-Gonzalez, scientific collaborator at the Institute for Environmental Sciences of the Sciences Faculty of UNIGE, investigated which of these hypotheses is more likely and under which climatic conditions one is more likely than the other. The question was addressed using inventory data from natural forests from five continents.

Forests of the Five Continents

"Having more species may not always be what is needed to achieve greater carbon storage in forests", states Dr. Madrigal-Gonzalez. Instead, this relation only seems to prevail in the most productive forest regions of the planet that are basically restricted to equatorial and tropical rain forests, and some temperate forests - in regions where deforestation and human-induced forest fires have ravaged pristine environments lately. On the contrary, in the forests located in the coldest or driest regions on Earth, it is seemingly the abundance, promoted by productivity, that determines the diversity. Here, any increase in the number of species will not necessarily result in more trees and will not therefore have a big contribution to carbon storage. The findings of these studies are of substantial practical relevance as they will aid decision makers identifying nature-based climate change mitigation strategies and to successfully use forests and their sequestration of carbon to reach the climate goals defined in the Paris Agreement. "Increasing climatic stress in the most productive forests of the planet could diminish or even collapse the role of diversity against climate change" says Prof. Markus Stoffel, Professor at the Institute for Environmental Sciences of the UNIGE.

East African Rift System is slowly breaking away, with Madagascar splitting into pieces

VIRGINIA TECH

Research News

 

IMAGE: GEOSCIENCES DOCTORAL STUDENT TAHIRY RAJAONARISON SETS UP A GPS INSTRUMENT IN NORTHERN MADAGASCAR IN THIS 2016 PHOTOGRAPH. PHOTO CREDIT: RINA ANDRIANASOLO. view more 

CREDIT: RINA ANDRIANASOLO

The African continent is slowly separating into several large and small tectonic blocks along the diverging East African Rift System, continuing to Madagascar - the long island just off the coast of Southeast Africa - that itself will also break apart into smaller islands.

These developments will redefine Africa and the Indian Ocean. The finding comes in a new study by D. Sarah Stamps of the Department of Geosciences for the journal Geology. The breakup is a continuation of the shattering of the supercontinent Pangea some 200 million years ago.

Rest assured, though, this isn't happening anytime soon.

"The rate of present-day break-up is millimeters per year, so it will be millions of years before new oceans start to form," said Stamps, an assistant professor in the Virginia Tech College of Science. "The rate of extension is fastest in the north, so we'll see new oceans forming there first."

Geosciences doctoral student Tahiry Rajaonarison sets up a GPS instrument in northern Madagascar in this 2016 photograph. Behind Tahir is the Indian Ocean and a rock island. Photo credit: Rina Andrianasolo.

"Most previous studies suggested that the extension is localized in narrow zones around microplates that move independent of surrounding larger tectonic plates," Stamps said. The new GPS dataset of very precise surface motions in Eastern Africa, Madagascar, and several islands in the Indian Ocean reveal that the break-up process is more complex and more distributed than previously thought, according to the study, completed by Stamps with researchers from the University of Nevada-Reno, University of Beira Interior in Portugal, and the Institute and Observatory of Geophysics of Antananarivo at the University of Antananarivo in Madagascar itself.

In one region, the researchers found that extension is distributed across a wide area. The region of distributed extension is about 600 kilometers (372 miles) wide, spanning from Eastern Africa to whole parts of Madagascar. More precisely, Madagascar is actively breaking up with southern Madagascar moving with the Lwandle microplate -- a small tectonic block -- and a piece of central Madagascar is moving with the Somalian plate. The rest of the island is found to be deforming nonrigidly, Stamps added.

Also working on the paper was geosciences Ph.D. student Tahiry Rajaonarison, who previously was a master's student at Madagascar's University of Antananarivo. He assisted Stamps in 2012 in collecting GPS data that was used in this study. He joined Virginia Tech in 2015 and returned to Madagascar later to collect more data as the lead on a National Geographic Society grant. "Leading a team to collect GPS data in Madagascar in summer 2017 was an amazing field experience," Rajaonarison said.

The team used new surface motion data and additional geologic data to test various configurations of tectonic blocks in the region using computer models. Through a comprehensive suite of statistical tests, the researchers defined new boundaries for the Lwandle microplate and Somalian plate. This approach allowed for testing if surface motion data are consistent with rigid plate motion.

Final model for the East African Rift System.

Hashed lines indicate newly discovered broad deforming zone. Arrows represent predicted tectonic plate motions. ABFZ--Andrew Bain Fracture Zone; IFZ--Indomed Fracture Zone; RSZ--Ranotsara shear zone. Figure created by D.S. Stamps.

"Accurately defining plate boundaries and assessing if continents diverge along narrowly deforming zones or through wide zones of diffuse deformation is crucial to unraveling the nature of continental break-up," Stamps said. "In this work, we have redefined how the world's largest continental rift is extending using a new GPS velocity solution."

The discovery of the broad deforming zone helps geoscientists understand recent and ongoing seismic and volcanic activity happening in the Comoros Islands, located in the Indian Ocean between East Africa and Madagascar. The study also provides a framework for future studies of global plate motions and investigations of the forces driving plate tectonics for Stamps and her team.

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