Power of Grassroots Innovation: How a Nondescript Box Has Been Saving Lives During the COVID Pandemic

The Conversation

By DOUGLAS HANNAH, BOSTON UNIVERSITY MARCH 27, 2022

A do-it-yourself air purifier in use in a classroom. Credit: Douglas Hannah, CC BY-ND

One afternoon, a dozen Arizona State University students gathered to spend the morning cutting cardboard, taping fans, and assembling filters in an effort to build 125 portable air purifiers for local schools. That same morning, staff members at a homeless shelter in Los Angeles were setting up 20 homemade purifiers of their own, while in Brookline, Massachusetts, another DIY air purifier was whirring quietly in the back of a daycare classroom as children played.

The technology in all three cases – an unassuming duct tape-and-cardboard construction known as a Corsi-Rosenthal box – is playing an important part in the fight against COVID-19. The story of how it came to be also reveals a lot about communities as sources of innovation and resilience in the face of disasters.

A simple technology with a big effect

As it became clear that COVID-19 was spread through airborne transmission, people started wearing masks and building managers rushed to upgrade their ventilation systems. This typically meant installing high-efficiency HEPA filters. These filters work by capturing virus-laden particles: Air is forced into a porous mat, contaminants are filtered out, and clean air passes through.

The efficacy of a building’s ventilation system is governed by two factors, though, not just the quality of the filters. The amount of air moved through the ventilation systems matters as well. Experts typically recommend five to six air changes per hour in shared spaces, meaning the entire volume of air in a room is replaced every 45 minutes. Systems in many older buildings can’t manage this volume, however.

Portable air filters are an option for augmenting ventilation systems, but they typically cost hundreds of dollars, which puts them out of range for schools and other public spaces that face budget constraints.

This is where the Corsi-Rosenthal box comes in. It’s a cube consisting of four to five off-the-shelf furnace filters topped by a standard box fan blowing outward. Once sealed together with tape, it can sit on a floor, shelf or table. The fan draws air through the sides of the cube and out the top. The units are simple, durable, and easy to make, and are more effective than simply placing a single filter in front of a box fan. It usually takes 40 minutes, minimal technical expertise, and US$60 to $90 in materials that are available from any home supply store.

Building a Corsi-Rosenthal box portable air filter comes down to duct-taping together a set of furnace filters and a box fan. Credit: Douglas Hannah, CC BY-ND

Despite this simplicity, though, these homemade units are extremely effective. When used in a shared space like a classroom or hospital ward, they can supplement existing ventilation and remove airborne contaminants, including smoke and virus-laden particles. A raft of recent peer-reviewed research has found portable air purifiers can dramatically reduce aerosol transmission. Other preprint and under-review studies have found Corsi-Rosenthal boxes perform as well as professional units at a fraction of the cost.

Origins of the Corsi-Rosenthal box

The formal story of the Corsi-Rosenthal box began in August 2020, when Richard Corsi, an air quality expert and now dean at the University of California, Davis, pitched the idea of building cheap box-fan air filters on Twitter. Jim Rosenthal, the CEO of a Texas-based filter company, had been playing around with a similar idea and quickly built the first prototype.

Within days, tinkerers and air quality engineers alike were constructing their own Corsi-Rosenthal boxes and sharing the results on social media. A vibrant conversation emerged on Twitter, blending sophisticated technical analysis from engineers with the insight and efforts of nonspecialists.

By December, hundreds of people were making Corsi-Rosenthal boxes, and thousands more had read press coverage in outlets like Wired. In different corners of the world, people tweaked designs based on the availability of supplies and different needs. Their collective improvements and adaptations were documented by dedicated websites and blogs, as well as news reports.

In some cases, design tweaks proved to be influential. In November 2020, for example, a homeowner in North Carolina discovered an issue with air being drawn back in through the corners of the most commonly used square fans. Subsequent testing by air quality experts showed that adding a shroud to the fan increased efficiency by as much as 50%.

Analyzing social media and news coverage gives a sense of the scale of the Corsi-Rosenthal box phenomenon. As of January 2022, more than 1,000 units were in use in schools, with thousands more in homes and offices. More than 3,500 people had used the hashtag #corsirosenthalbox on Twitter, and tens of thousands more contributed to the online conversation. News articles and explainer videos on YouTube had collectively accumulated more than 1.9 million views.

Communities as sources of innovation

The story of the Corsi-Rosenthal box is part of a broader story of the grassroots response to the COVID-19 pandemic. The early days of the pandemic did more than just take a terrible toll on people. They also galvanized a massive entrepreneurial effort, with tens of thousands of everyday citizens lending their hands to design and produce the critical medical supplies and personal protective equipment that was suddenly needed.

Corsi-Rosenthal boxes assembled and awaiting delivery to a homeless shelter in California. Credit: Douglas Hannah, CC BY-ND

My research team has been tracking these efforts. Through dozens of interviews and months of archival research, we’ve built a database of more than 200 startups – formal and informal, nonprofit and for-profit – whose activities ranged from designing oxygen concentrators to 3D printing face shields to building UV disinfection rooms. The picture of innovation that emerges is a far cry from the traditional lab coats and middle managers image that is commonly associated with new technologies.

First, few of the innovations we’ve tracked were actually invented by a single person, or even a single team. Rather, they were the joint project of broad networks of individual contributors from different backgrounds and organizations. This breadth is important because it brings more knowledge and more diverse perspectives. It can also be helpful for tapping existing knowledge. For example, as Corsi-Rosenthal boxes gained traction, the community was able to draw on earlier iterations that had been developed to help with wildfire smoke.

Second, the innovation process lacked hierarchical control. There was no single person directing where or how the technology was used. This lack of control made it easier to experiment and adapt to local conditions. One example is the development of oxygen concentrators for use in hospitals in India. Realizing that existing Western technologies failed frequently in the more humid operating environment typical of India, teams of innovators rallied to develop and share improved open-source designs.

Third, these communities shared knowledge online. This allowed individual contributors to communicate directly and share ideas, which helped knowledge spread rapidly through the network. It also meant that knowledge was more readily accessible. The detailed designs and test results from air quality engineers working on Corsi-Rosenthal boxes were readily available to anyone in the community.

Also, most of the organizations we tracked used Facebook, Twitter and Slack as tools to manage collaboration within and between organizations. As I and others have argued, this gives grassroots innovation tremendous promise – especially in a world where large-scale disruptions like a pandemic are increasingly common.

Pitfalls of grassroots innovation

Despite this promise, there are areas in which grassroots innovation communities falter. One challenge is a lack of technological sophistication and resources. While some of the communities in our study produced remarkably complex devices, the greatest contribution was in far simpler products like face shields and surgical gowns.

Then there are rules and regulations. Even when grassroots communities can produce safe and effective innovations, existing rules may not be ready to receive them. Some hospitals were unable to accept personal protective equipment provided by the community during the pandemic because of inflexible procurement policies, and today some schools continue to prohibit Corsi-Rosenthal boxes.

A final issue is sustaining effort. While grassroots communities were vital to allowing hospitals and medical facilities to remain functioning during the early days of the pandemic, many of the efforts that depended on volunteer labor eventually ran out of steam.

What this means for the future

As the second anniversary of the U.S. declaration of emergency approaches, a key lesson the world has learned is the importance of investing in indoor air quality, for example through monitoring and improved ventilation and filtration. And the value of ventilation as a noninvasive public health tool is even greater as mask mandates wane.

Another, broader lesson is the power of grassroots innovation and citizen engineering to develop these technologies. The story of the Corsi-Rosenthal box, like the thousands of other grassroots innovations developed during the pandemic, is fundamentally about people taking the welfare of their communities into their own hands. The most popular tweet shared about Corsi-Rosenthal boxes was from a 14-year-old aspiring engineer in Ontario offering to build and donate boxes to anyone in need.

Written by Douglas Hannah, Assistant Professor of Strategy and Innovation, Boston University.

This article was first published in The Conversation.

Scientists Find Ways To Reconstruct Ancient 

Scents

By MAX PLANCK INSTITUTE FOR THE SCIENCE OF HUMAN HISTORY MARCH 28, 2022

Past scents can be recovered from scent archives by extracting molecules using a variety of different methods. With successful detection and identification of the molecular composition of samples, ancient sources of smell can then be identified. Credit: Michelle O’Reilly

In recent years, millions of people worldwide have suffered the loss of smell due to COVID-19. Even those who have avoided infection with the new coronavirus experience the world of scent differently now due to the very masks that provide protection from the virus. This loss of olfaction has highlighted the important role of smell in how we perceive and navigate the world, and underscored the connections between olfaction and mental and physical health.

Scent has always been an integral component of the human experience, but up until now, the past has remained largely odorless. Most scents come from organic substances that decay quickly, leaving little for archaeologists to investigate thousands of years later. Now a team of researchers from the MPI for the Science of Human History is looking for new ways to bring the smellscapes of the past back to life and using smell to study past experience, behavior, and society.

“Tracking scent in the deep past is not a simple task,” says Barbara Huber, the lead author of the paper, “but the fact that history records expeditions of discovery, wars, and long-distance exchange to acquire materials with strong olfactory properties – like incense and spices – reveals how significant scent has been for humankind.”

Scent data can be contextualized within the framework of relevant historical texts and visual representations, as well as the archaeological and environmental records. Connecting these different sources of information enables the reconstruction of critical aspects of ancient lifeways and society (indicated by arrows emerging from the blue circle). The icons in the outer area of the figure represent examples of some of the themes that can be addressed through this approach (grey boxes indicate broad headings). Credit: Michelle O’Reilly

Understanding the sensorial dimension of human history and the use of odorous and aromatic substances can contribute knowledge about many aspects of the past – including ritual, perfumery, hygiene, cuisine, trade, and commerce. But because scent is part of how we experience, understand, and navigate the world, ancient scents can also provide insight into more general aspects of the past, from social hierarchy and social practices to group identity.

“Scent is a powerful and underappreciated aspect of human experience,” notes Professor Nicole Boivin, senior author of the study and Director of the Department of Archaeology at the MPI Science of Human History “Smells reach our brain fairly directly and motivate us in critical ways – whether to avoid danger, identify something that is good for us, or remember something from our past, for example.”

“Using only traces of scented substances preserved in archaeological artifacts and features,” adds Huber, “novel methods are revealing the powerful odors that were a cardinal feature of ancient lived realities, and that shaped human action, thoughts, emotions, and memories.”

By leveraging potent new biomolecular and omics approaches, such as proteomic and metabolomics techniques, and linking new data with information from ancient texts, visual depictions, and the broader archaeological and environmental records, researchers stand to open up new aspects of the ancient world, our changing societies and cultures, and our evolution as a species. The authors of the new paper hope that more research into the rich ‘smellscapes’ of the past will provide insight into the sensory worlds of long ago, and the diverse ways that people have captured scents from nature in order to shape human experience. 

Reference: “How to use modern science to reconstruct ancient scent” 28 March 2022, Nature Human Behaviour.
DOI: 10.1038/s41562-022-01325-7

 

Stunning Subsurface Images of Yellowstone National Park Reveal “Mystery Sandwich” Plumbing System

 

By VIRGINIA TECH MARCH 28, 2022

The SkyTEM instrument being flown over Old Faithful in Yellowstone National Park. Credit: Photo by Jeff Hungerford, Yellowstone National Park; supplied by Carol Finn of U.S. Geological Survey

The geysers and fumaroles of Yellowstone National Park are among the most iconic and popular geological features on our planet. Each year, millions of visitors travel to the park to marvel at the towering eruptions of Old Faithful, the bubbling mud cauldrons of Artists Paint Pots, the crystal-clear water, and iridescent colors of Grand Prismatic Spring, and the stacked travertine terraces of Mammoth Hot Springs.

Those who have visited the park may have asked themselves, “Where does all the hot water come from?” A study published last week in Nature, co-authored by Virginia Tech’s W. Steven Holbrook and colleagues from the U.S. Geological Survey and Aarhus University in Denmark, provides stunning subsurface images that begin to answer that question.

The research team used geophysical data collected from a helicopter to create images of Yellowstone’s subsurface “plumbing” system. The method detects features with unusual electrical and magnetic properties indicative of hydrothermal alteration.

“The combination of high electrical conductivity and low magnetization is like a fingerprint of hydrothermal activity that shows up very clearly in the data,” said Holbrook, a professor of geophysics and head of the Department of Geosciences in Virginia Tech’s College of Science. “The method is essentially a hydrothermal pathway detector.”

Images from the study show that the park’s geology profoundly shapes its hot springs. Hot hydrothermal fluids ascend nearly vertically, from depths of more than 1 km (or .62 miles), to arrive at the park’s major hydrothermal fields. Along the way, they mix with shallower groundwater flowing within and beneath the park’s volcanic lava flows, which also are visible in the images. Faults and fractures guide the ascent of hydrothermal waters, while lava flow boundaries control the shallow groundwater aquifers.

An example of a subsurface image of Yellowstone hydrothermal features produced from SkyTEM data. Blue colors are electrically conductive hydrothermal pathways; red features are electrically resistive lava flows. This line crosses two hydrothermal areas, one in the center of the figure that is near Old Faithful, and one labeled “FM” for Firehole Meadows. Credit: W. Steven Holbrook / Virginia Tech

The project fills in a longstanding knowledge gap about the underpinnings of Yellowstone’s charismatic hydrothermal features. Much is known about the park’s surface hydrothermal features, including the chemistry and temperature of mud pots and springs, the eruption interval of geysers, and the unique thermophilic bacteria that live in and around those features.

Likewise, scientists have a growing body of knowledge about the deeper heat sources and tectonic activity by tracking earthquakes that occur there. But little is known about how the surface hydrothermal features are connected to each other and to the deeper sources of heat and fluids.

“Our knowledge of Yellowstone has long had a subsurface gap,” Holbook said. “It’s like a ‘mystery sandwich’ — we know a lot about the surface features from direct observation and a fair amount about the magmatic and tectonic system several kilometers down from geophysical work, but we don’t really know what’s in the middle. This project has enabled us to fill in those gaps for the first time.”

To collect the data, the team used a unique instrument called “SkyTEM” that consists of a large loop of wire towed beneath a helicopter. As the helicopter flies, the loop sends downward repeated electromagnetic signals that provoke a response from electrically conductive bodies in the subsurface.

That response is recorded and later analyzed to produce detailed cross-sections along the flight lines. The technique is highly effective in environments like Yellowstone: hydrothermal fluids alter the rocks they pass through, turning rock into clay minerals — for example, the surface mud pots — that have heightened electrical conductivity but suppressed magnetization.

Steve Holbrook, professor and head of the Department of Geosciences. Credit: Mike Lee for Virginia Tech

Because the helicopter is able to travel at speeds of 40 to 50 mph while towing the SkyTEM instrument, scientists involved in the study were able to cover large swaths of the sprawling, 3,500-square-mile national park, Holbrook said.

“One of the unique aspects of this dataset is its extensive coverage of this huge system,” Holbrook added. “We were able not just to look deep beneath the hydrothermal features, but also to see how adjacent features might be connected in the subsurface across great distances. That’s never been possible before.”

One of the mysteries addressed by the new work is whether different hydrothermal areas in the park show contrasting deep fluid sources and pathways. The team found a remarkable similarity in the deep structure beneath areas such as Norris Geyser Basin and Lower Geyser Basin, suggesting that contrasts in the chemistry and temperatures of those areas are not caused by deep processes. Instead, variable degrees of mixing with shallow groundwater likely create the wide variety of hot spring characteristics in the park.

Overall, the project generated more than 2,500 miles of helicopter lines, an enormous amount of data, according to Holbrook. Upon the study’s publication last month, the research team released the data so that others can undertake additional research.

“The data set is so big that we’ve only scratched the surface with this first paper,” Holbrook added. “I look forward to continuing to work on this data and to seeing what others come up with, too. It’s going to be a data set that keeps on giving.”

Before coming to Virginia Tech in 2017, Holbrook was part of the Department of Geology and Geophysics at the University of Wyoming in Laramie, Wyoming. He also co-directed the Wyoming Center for Environmental Hydrology and Geophysics. He said, “I’ve made several field trips to collect ground-based geophysical data in Yellowstone. The airborne data covers a lot more ground much more quickly than we could by hiking gear into the backcountry, though.”

Carol Finn of the U.S. Geological Survey and lead author on the study said, “While the airborne data were still being collected, we saw the first images over Old Faithful and knew instantly that our experiment had worked — that we could, for the first time, image the fluid pathways that had long been speculated.”

She added, “Our work has sparked considerable interest across a range of disciplines, including biologists looking to link areas of groundwater and gas mixing to regions of extreme microbiological diversity, geologists wanting to estimate volumes of lava flows, and hydrologists interested in modeling flow paths of groundwater and thermal fluid. With the paper as a guide and the release of the data and models, we will enable research in these diverse scientific communities.”

One mystery that Holbrook is interested in pursuing further is evidence for distant connections between isolated surface hydrothermal areas. The SkyTEM data show evidence for subsurface linkages between hydrothermal systems that are up to 6 miles apart.

“That might have implications for the co-evolution of thermophilic bacteria and Archaea,” Holbrook said. “The notion that airborne geophysical data could illuminate something about the life of microscopic organisms living around hot springs is a fascinating idea.”

Reference: “Geophysical imaging of the Yellowstone hydrothermal plumbing system” by Carol A. Finn, Paul A. Bedrosian, W. Steven Holbrook, Esben Auken, Benjamin R. Bloss and Jade Crosbie, 23 March 2022, Nature.
DOI: 10.1038/s41586-021-04379-1

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Smoke from Australia’s intense fires in 2019 and 2020 damaged the ozone layer

Increasingly large blazes threaten to undo decades of work to help Earth’s protective layer

A towering cloud of smoke rises over the Green Wattle Creek bushfire

 on December 21, 2019, near the township of Yanderra in New South Wales, Australia.

By Carolyn Gramling
MARCH 17, 2022 

Towers of smoke that rose high into the stratosphere during Australia’s “black summer” fires in 2019 and 2020 destroyed some of Earth’s protective ozone layer, researchers report in the March 18 Science.

Chemist Peter Bernath of Old Dominion University in Norfolk, Va., and his colleagues analyzed data collected in the lower stratosphere during 2020 by a satellite instrument called the Atmospheric Chemistry Experiment. It measures how different particles in the atmosphere absorb light at different wavelengths. Such absorption patterns are like fingerprints, identifying what molecules are present in the particles.

The team’s analyses revealed that the particles of smoke, shot into the stratosphere by fire-fueled thunderstorms called pyrocumulonimbus clouds, contained a variety of mischief-making organic molecules (SN: 12/15/20). The molecules, the team reports, kicked off a series of chemical reactions that altered the balances of gases in Earth’s stratosphere to a degree never before observed in 15 years of satellite measurements. That shuffle included boosting levels of chlorine-containing molecules that ultimately ate away at the ozone.

Ozone concentrations in the stratosphere initially increased from January to March 2020, due to similar chemical reactions — sometimes with the contribution of wildfire smoke — that produce ozone pollution at ground level (SN: 12/8/21). But from April to December 2020, the ozone levels not only fell, but sank below the average ozone concentration from 2005 to 2019.

Earth’s ozone layer shields the planet from much of the sun’s ultraviolet radiation. Once depleted by human emissions of chlorofluorocarbons and other ozone-damaging substances, the layer has been showing signs of recovery thanks to the Montreal Protocol, an international agreement to reduce the atmospheric concentrations of those substances (SN: 2/10/21).

But the increasing frequency of large wildfires due to climate change — and their ozone-destroying potential — could become a setback for that rare climate success story, the researchers say (SN: 3/4/20).

Questions or comments on this article? E-mail us at feedback@sciencenews.org

CITATIONS

P. Bernath, C. Boone and J. Crouse. Wildfire smoke destroys stratospheric ozone. Science. Vol. 375, March 18, 2022, p. 1,292. doi: 10.1126/science.abm5611.

About Carolyn Gramling
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Carolyn Gramling is the earth & climate writer. She has bachelor’s degrees in geology and European history and a Ph.D. in marine geochemistry from MIT and the Woods Hole Oceanographic Institution.

Palpable Change in Fire Dynamics Confirmed: U.S. Wildfires 4x Larger, 3x More Frequent Since 2000

By UNIVERSITY OF COLORADO AT BOULDER MARCH 28, 2022

This is a 2013 photo of the Alder Fire in Yellowstone National Park. Credit: Mike Lewelling, National Park Service

New analysis confirms a palpable change in fire dynamics already suspected by many.

Fires have gotten larger, more frequent, and more widespread across the United States since 2000, according to a new CIRES Earth Lab-led paper. Recent wildfires have stoked concern that climate change is causing more extreme events, and the work published recently in Science Advances shows that large fires have not only become more common, they are also spreading into new areas, impacting land that previously did not burn.

“Projected changes in climate, fuel, and ignitions suggest that we’ll see more and larger fires in the future. Our analyses show that those changes are already happening,” said Virginia Iglesias, a research scientist with CIRES’ Earth Lab and lead author of the paper.

To evaluate how the size, frequency, and extent of fires have changed in the United States, Iglesias and her colleagues analyzed data from over 28,000 fires that occurred between 1984 and 2018 from the Monitoring Trends in Burn Severity (MTBS) dataset, which combines satellite imagery with the best available state and federal fire history records.

A DC-10 drops fire retardant on the edge of the 2020 Calwood Fire in Colorado. Credit: William Travis, University of Colorado

The team found that there were more fires across all regions in the contiguous United States from 2005 to 2018 compared to the previous two decades. In the West and East, fire frequency doubled, and in the Great Plains, fire frequency quadrupled. As a result, the amount of land burned each year increased from a median of 1,552 to 5,502 square miles (4,019 to 14,249 km²) in the West and from 465 to 1,295 square miles (1,204 to 3,354 km²) in the Great Plains.

The researchers also took a closer look at the most extreme fire events in each region. They found that in the West and Great Plains, the largest wildfires grew bigger and ignited more often in the 2000s. Throughout the record, large fires were more likely to occur around the same time as other large fires.

“More and larger co-occurring fires are already altering vegetation composition and structure, snowpack and water supply to our communities,” Iglesias explained. “This trend is challenging fire-suppression efforts and threatening the lives, health, and homes of millions of Americans.”

Finally, the team discovered that the size of fire-prone areas increased in all regions of the contiguous United States in the 2000s, meaning that not only is the distance between individual fires getting smaller than it was in the previous decades, but also that fires are spreading into areas that did not burn in the past. 

These results confirm a palpable change in fire dynamics that has been suspected by the media, public, and fire-fighting officials. Unfortunately, the results also align with other troubling risk trends, such as the fact that development of natural hazard zones is also increasing wildfire risk. “These convergent trends, more large fires plus intensifying development, mean that the worst fire disasters are still to come,” said co-author and Earth Lab deputy director, William Travis.

The study authors suggest that to adapt and build resilience to wildfire impacts, planners and stakeholders must account for how fire is changing and how it is impacting vulnerable ecosystems and communities.

Reference: “U.S. fires became larger, more frequent, and more widespread in the 2000s” by Virginia Iglesias, Jennifer K. Balch and William R. Travis, 16 March 2022, Science Advances.
DOI: 10.1126/sciadv.abc0020

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Tonga Volcano Eruption Caused Massive Space Plasma Disturbances on a Global Scale

By NANCY WOLFE KOTARY, MIT HAYSTACK OBSERVATORY MARCH 26, 2022

This looping video shows a series of GOES-17 satellite images that caught an umbrella cloud generated by the underwater eruption of the Hunga Tonga-Hunga Ha’apai volcano on January 15, 2022. Crescent-shaped bow shock waves and numerous lighting strikes are also visible. Credit: NASA Earth Observatory image by Joshua Stevens using GOES imagery courtesy of NOAA and NESDIS

MIT Haystack Observatory identifies long-duration atmospheric waves launched by the recent Tonga eruption.

The recent eruption of Tonga’s Hunga Tonga–Hunga Ha‘apai volcano, at 04:14:45 UT on January 15, 2022, was recently confirmed to have launched far-reaching, massive global disturbances in the Earth’s atmosphere.

Using data recorded by more than 5,000 Global Navigation Satellite System (GNSS) ground receivers located around the globe, MIT Haystack Observatory scientists and their international partners from the Arctic University of Norway have observed substantial evidence of eruption-generated atmospheric waves and their ionospheric imprints 300 kilometers above the Earth’s surface over an extended period. These atmospheric waves were active for at least four days after the eruption and circled the globe three times. Ionospheric disturbances passed over the United States six times, at first from west to east and later in reverse.

This volcanic event was extraordinarily powerful, releasing energy equivalent to 1,000 atomic bombs of the size deployed in 1945. Scientists have known that explosive volcanic eruptions and earthquakes can trigger a series of atmospheric pressure waves, including acoustic waves, and that they can perturb the upper atmosphere a few hundred kilometers above the epicenter. When over the ocean, they can trigger tsunami waves, and therefore upper-atmospheric disturbances. Results from this Tonga eruption have surprised this international team, particularly in their geographic extent and multiple-day durations. These discoveries ultimately suggest new ways in which the atmospheric waves and the global ionosphere are connected.

A new study, led by researchers at MIT Haystack Observatory and the Arctic University of Norway, reporting the results was published on March 23, 2022, in the peer-reviewed journal Frontiers in Astronomy and Space Sciences.

Traveling ionospheric disturbances following an eruption in the kingdom of Tonga in the South Pacific Ocean, as measured from the global GNSS networks of receivers. The horizontal axis shows time; the vertical axis shows distance. Yellow areas within the white-line envelope as marked by fiducial arrows are enhanced ionospheric disturbances in total electron content (TEC). Distance is measured along Great-Circle loci with origin at Tonga. The positive and negative distance shows TIDs propagating both northward and southward from Tonga. The eruption antipode is in North Africa, approximately 21,000 km away from Tonga. TIDs took 17-18 hours to reach the antipode and the same time to return to Tonga on the next day. Credit: Shunrong Zhang/Haystack Observatory

The authors believe the disturbances to be an effect of Lamb waves; these waves, named after mathematician Horace Lamb, travel at the speed of sound globally without much reduction in amplitude. Although they are located predominantly near Earth’s surface, these waves can exchange energy with the ionosphere through complex pathways. As stated in the new paper, “prevailing Lamb waves have been reported before as atmospheric responses to the Krakatoa eruption in 1883 and other geohazards. This study provides substantial first evidence of their long-duration imprints up in the global ionosphere.”

Under National Science Foundation support, Haystack has been assembling global GNSS network observations to study important total electron content information on a daily basis since 2000. The observatory shares this data with the international geospace community to enable innovative research on a variety of frontiers, ranging from solar storm effects to low atmospheric forcing. A particular form of space weather, caused by ionospheric waves called traveling ionospheric disturbances (TIDs), are often excited by processes including sudden energy inputs from the sun, terrestrial weather, and human-made disturbances. For example, Haystack scientists used TID observations to provide the first evidence that solar eclipses can trigger bow waves in Earth’s atmosphere.

Lead author Shunrong Zhang says, “Only severe solar storms are known to produce TID global propagation in space for several hours, if not for days; volcanic eruptions and earthquakes normally yield ionospheric disturbances only within thousands of kilometers. By detecting these significant eruption-induced ionospheric disturbances in space over very large distances, we found not only generation of Lamb waves and their global propagation over several days (often monitored as sound waves on the ground for compliance with Comprehensive Nuclear Test Ban Treaties) but also a fundamental new physical process. In the end, surface and lower atmospheric signals can make a loud splash, even deep in space.”

Beyond these results, Haystack scientists continue additional studies of the Tonga eruption’s generation of severe space weather effects.

Reference: “2022 Tonga Volcanic Eruption Induced Global Propagation of Ionospheric Disturbances via Lamb Waves” by Shun-Rong Zhang, Juha Vierinen2, Ercha Aa, Larisa P. Goncharenko, Philip J. Erickson, William Rideout, Anthea J. Coster and Andres Spicher, 23 March 2022, Frontiers in Astronomy and Space Sciences.
DOI: 10.3389/fspas.2022.871275

Describing the devastating eruption in Tonga

Date: March 29, 2022

Source: University of California - Santa Barbara

On January 15, the volcano Hunga Tonga-Hunga Ha'apai devastated the nation of Tonga. The eruption triggered tsunamis as far afield as the Caribbean and generated atmospheric waves that travelled around the globe several times. Meanwhile, the volcano's plume shot gas and ash through the stratosphere into the lower mesosphere.

Just two months after the eruption, geologists have put together a preliminary account of how it unfolded. UC Santa Barbara's Melissa Scruggs and emeritus Professor Frank Spera were part of an international team of researchers that published the first holistic account of the event in the journal Earthquake Research Advances. The authors think that an eruption the day before may have primed the volcano for the violent explosion by sinking its main vent below the ocean's surface. This enabled molten rock to vaporize a large volume of seawater, intensifying the volcanic eruption the very next day.

"This is definitely, without a doubt, the largest eruption since Mt. Pinatubo in 1991," said corresponding author Scruggs, who studies magma mixing and eruption triggering mechanisms, and recently completed her doctorate at UC Santa Barbara. She compared January's event to the 1883 eruption of Krakatoa, which was heard 3,000 miles away.

Hunga Tonga-Hunga Ha'apai (HTHH) is a stratovolcano: a large, cone-shaped mountain that is prone to periodic violent eruptions, but which usually experiences milder activity. It's one of many along the Tofua Volcanic Arc, a line of volcanoes fed by magma from the Pacific Plate diving beneath the Indo-Australian Plate. Heat and pressure cook the rocks of the descending plate, driving out water and other volatiles. That same water decreases the melting temperature of the rock above, leading to a chain of volcanoes about 100 kilometers from the plate boundary.

A submerged danger

The islands of Hunga Tonga and Hunga Ha'apai -- after which the volcano is named -- are merely the two highest points along the rim of the caldera, or central crater. Or they were, until the eruption blew most of the islands sky high.

Scruggs first heard about the eruption as she scrolled through her Twitter feed while getting ready for bed. "I saw a GIF of the satellite eruption, and my heart just stopped," she said, pausing to find her words. She immediately knew that the event would cause massive devastation. "The scariest part was that the entire country was cut off, and we didn't know what had happened."

She was already messaging other volcanologists as the events unfolded, trying to understand the images that satellites had so clearly captured. "We really just set out to try to understand what happened," Scruggs said. "So, we gathered all the information that we could, anything that was available within the first few weeks." The authors drew on whatever resources they could find to quickly characterize this eruption, including publicly available data, videos and even tweets.

Using a variety of data sets, the team calculated that the January 15 event began at 5:02 p.m. local time (0402 ±1 UTC). The U.S. Geological Survey recorded a seismic event around 13 minutes later at the vent location. The first two hours of the eruption were particularly violent, with activity fading after about 12 hours.

But eruption activity had actually started all the way back on December 20, 2021. And before that, the volcano had erupted in 2009 and again in 2014 and 2015. Scruggs believes these earlier episodes are key to understanding the violence behind HTHH's recent eruption, perhaps related to changes in the magma plumbing system at depth or the chemistry of the magma over time.

Hunga Tonga and Hunga Ha'apai used to be separate islands until they were united by eruptions from the volcano's main vent, which created a land bridge. "This island was just born in 2015," said Scruggs. "And now it's gone. Were it not for the satellite era, we would not have even known it ever existed."

On January 14, 2022 an explosion from the main vent razed this connection, sinking the vent beneath the ocean's surface. "Had that land bridge not been taken out, the January 15 eruption might have behaved just like the day before because it would not have had that excess seawater," Scruggs remarked.

A staggering explosion

Same volcano, one day's difference: On Friday the vent was above the water, and by Saturday it was below. "That made all of the difference in the world," Scruggs said.

The team believes that the seawater played a large part in the violence and force behind the Jan. 15 eruption. Much like a bottle rocket, an eruption of this scale takes the right ratio of water and gas to provide the force to send it skyward.

And it took off like a rocket, too. "It went halfway to space," Scruggs exclaimed. The ash plume shot 58 kilometers into the atmosphere, past the stratosphere and into the lower mesosphere. This is more than twice the height reached by the plume from Mt. Saint Helens in 1980. It was the tallest volcanic plume ever recorded.

A truly staggering amount of lightning also accompanied the eruption. The authors suspect that vaporizing seawater caused the lava to fragment into microscopic ash particles, which were joined by tiny ice crystals once the steam froze in the upper atmosphere. The motion, temperature change and size of the particles generated incredible amounts of static charge separation that flashed above the eruption. For the first two hours of the eruption, about 80% of all lightning strikes on Earth split the sky above Hunga Tonga-Hunga Ha'apai.

The authors estimate around 1.9 km3 of material, weighing 2,900 teragrams, erupted from HTHH on Jan. 15. "But the volume of the eruption was not the big deal," said Spera, a coauthor on the paper and Scruggs' doctoral advisor. "What was special is how the energy of the eruption coupled to the atmosphere and oceans: A lot of the energy went into moving air and water on a global scale."

The shockwave traveling through the ocean triggered tsunamis throughout the Pacific, and beyond. What's more, the wave arrived faster than tsunami warning models predicted because the models aren't calibrated for volcanic eruptions -- they're based on equations that describe tsunamis generated by earthquakes.

A second tsunami followed the atmospheric pressure wave. This shockwave even triggered a meteo-tsunami in the Caribbean, which has no direct connection to the South Pacific. Scruggs called it unprecedented: "Basically the whole ocean just kind of sloshed around for five days after the eruption," she added.

Plenty of work to do

Scientists are still piecing together what happened at the volcano, so they have yet to develop a complete understanding of the tsunami wave. However, it's an important task needed to update tsunami travel forecast systems so they account for this type of mechanism. Otherwise, warnings could be incorrect the next time a volcano like HTHH erupts, potentially costing more lives.

Indeed, the event highlights the danger posed by unmonitored submarine volcanoes. Despite the devastation, the people of Tonga were relatively well prepared for the Jan. 15 eruption. The government had issued warnings based on the previous day's activity, and the nation had plans in place for eruptions and tsunamis.

HTHH has experienced similarly violent eruptions in the past. A recent paper by researchers at the University of Otago, New Zealand revealed that a large eruption destroyed the caldera at the summit of the undersea volcano about 1,000 years ago. And similar volcanoes could well erupt in the same manner. Consider Kick 'em Jenny, another submarine volcano whose main vent is a mere 150 meters underwater. It's located just 8 km north of the island of Grenada. "Imagine if something like the Tonga eruption happened in the Caribbean," Scruggs said.

The researchers worked quickly with only publicly available data. They plan to revisit all their findings as more information and samples become available and as more researchers publish their own findings on this groundbreaking eruption. Their primary goal was to provide a point of departure for future work on the topic.

Scruggs is particularly keen on learning about the ash collected from this eruption. Volcanic rock provides a wealth of information to a trained geologist. Examining the material could shed light on the type of magma that erupted, how much of it there was and perhaps even how much seawater was involved in the eruption.

"There's so many questions that have been raised," said Scruggs. "Things we didn't even think were possible have now been recorded."

The UC Santa Barbara researchers will lead a special invited session on the Hunga Tonga-Hunga Ha'apai eruption at the Geological Society of America's 2022 annual meeting in Denver this October. "It will be exciting to see what scores of other earth scientists can discover about this unique volcano," Spera said. "We are just at the beginning."

Journal Reference:
David A. Yuen, Melissa A. Scruggs, Frank J. Spera, Yingcai Zheng, Hao Hu, Stephen R. McNutt, Glenn Thompson, Kyle Mandli, Barry R. Keller, Songqiao Shawn Wei, Zhigang Peng, Zili Zhou, Francesco Mulargia, Yuichiro Tanioka. Under the Surface: Pressure-Induced Planetary-Scale Waves, Volcanic Lightning, and Gaseous Clouds Caused by the Submarine Eruption of Hunga Tonga-Hunga Ha’apai Volcano Provide an Excellent Research Opportunity. Earthquake Research Advances, 2022; 100134 DOI: 10.1016/j.eqrea.2022.100134