Tuesday, August 01, 2023

Plans to plant billions of trees threatened by massive undersupply of seedlings

US efforts to fight climate change with tree planting at risk from lack of stock and species diversity, new research shows

Peer-Reviewed Publication

UNIVERSITY OF VERMONT

Map: Red Oak Seed Sources — IMAGE: THIS MAP OF RED OAK SEED SOURCES PROVIDES AN EXAMPLE OF A MAJOR THREAT TO AN IMPORTANT EFFORT AGAINST CLIMATE CHANGE: MAJOR GOVERNMENT AND PRIVATE FUNDING IS BEING INVESTED IN PLANTING TREES AS A POWERFUL TOOL TO FIGHT LOCAL AND GLOBAL WARMING. BUT NEW RESEARCH IN THE JOURNAL BIOSCIENCE, FROM WHICH THIS MAP IS ADAPTED, SHOWS A TROUBLING BOTTLENECK THAT COULD THREATEN THESE EFFORTS: U.S. TREE NURSERIES DON’T GROW CLOSE TO ENOUGH TREES—NOR HAVE THE SPECIES DIVERSITY NEEDED—TO MEET AMBITIOUS PLANTING GOALS. view more
CREDIT: ADAPTED FROM PETER CLARK/BIOSCIENCE

The REPLANT Act provides money for the US Forest Service to plant more than a billion trees in the next nine years. The World Economic Forum aims to help plant a trillion trees around the world by 2030. Many US cities have plans to shade their streets with millions of trees. Major government and private funding is being invested in planting trees as a powerful tool to fight climate change, protect water, clean air, and cool cities. In short, trees are hot.

But new research shows a troubling bottleneck that could threaten these efforts: U.S. tree nurseries don’t grow close to enough trees—nor have the species diversity needed—to meet ambitious plans.

The study was published in the journal Bioscience on July 31, 2023.

Seedling Scarcity

“Trees are this amazing natural solution to a lot of our challenges, including climate change. We urgently need to plant many millions of them,” says University of Vermont scientist Tony D’Amato who co-led the new research. “But what this paper points out is that we are woefully underserved by any kind of regional or national scale inventory of seedlings to get the job done.”

A team of 13 scientists, led by D’Amato and UVM post-doctoral scientist Peter Clark, studied 605 plant nurseries across twenty northern states. Only 56 of these grow and sell seedlings in the volumes needed for conservation and reforestation and only 14 of them were government-operated, they report. The team was more dismayed to discover an “overwhelming scarcity of seedlings,” they write, from different species and “seed collection zones”—trees adapted to local conditions and climate. In essence, forest nurseries tended to maintain a limited inventory of a select few species, electing to prioritize those valued for commercial timber production over species required for conservation, ecological restoration, or climate adaptation. Moreover, many areas had no locally adapted tree stock available. (See map for example.) And within the seedlings available, there were not enough types of trees and “future-climate-suitable” genetics to meet goals for conservation and forest restoration in a hot future.

“The world is thinking about a warming climate—can we plant towards that warming climate? We know we’re losing ecologically important species across North America and around the world. So, the goal is: can we restore these trees or replace them with similar species? It’s a powerful idea,” says UVM’s Peter Clark, the lead author on the new study. “But—despite the excitement and novelty of that idea in many policy and philanthropy circles—when push comes to shove, it's very challenging on the ground to actually find either the species or the seed sources needed.”

“The number of seedlings is a challenge,” Clark says, “but finding the diversity we need to restore ecologically complex forests—not just a few industrial workhorse species commonly used for commercial timber operations, like white pine—is an even bigger bottleneck.”

One extreme example is red spruce. This ecologically important species along hundreds of miles of eastern North America has been under stress for decades from climate change, pests, and land clearing. Yet, in their 20-state survey, the team only found two tree nurseries that had inventory of red spruce, a species from which many millions of seedlings are needed to meet restoration goals. “Remarkably, only 800 red spruce seedlings were commercially available for purchase in 2022,” the team reports in their new Bioscience study, “—enough to reforest less than one hectare.”

“It really points to just how bare the cupboard is when it comes to the diversity of options,” says Tony D’Amato, director of the Forestry Program in UVM’s Rubenstein School of Environment and Natural Resources, “but also the quantity that's needed to make any meaningful impact.”

Increased Investment

The team argues that dramatic increases in both seedling production and diversity at many regional nurseries will be central to any successful campaign to address climate change with tree planting. However, the novelty and risk involved, “likely generates uncertainty among forest nurseries, hampering investment,” they write. This appears to be especially true in regions, like the Northeast, where nurseries have declined over recent decades, the study reports, and where speculative investment—in growing new, future-climate-adapted, non-timber species and seedlots—may carry high financial risk.

Additionally, seedlings brought in from outside a region may be less likely to succeed. The new study reports that the vast majority (80%) of seedlings in the northern states, where the study was conducted, are produced in the North Central states—and very few in the Northeastern states. “Such concentration of production will hinder tree planting efforts,” they write, “because species and seed sources likely originate from similar geographic or bioclimatic zones.” On top of this challenge, seedlings are sensitive to stress. A misalignment between when seedlings are available—say in a southern nursery months before northern soils are frost free—and when they are needed, may doom their chances.

The team of researchers—including scientists from UVM; the USDA’s Northern Forest Research Stations in Minnesota, Michigan and New Hampshire; Minnesota Department of Natural Resources; Wisconsin Department of Natural Resources; Michigan Department of Natural Resources; University of Minnesota; the USDA’s Northern Institute of Applied Climate Science; and The Nature Conservancy (Albany, NY)—recommend a series of improvements from improved policy and financing to better training and expanded research.

For example, today government agencies, such as the US Forest Service and many US state governments, lack clear policies about the movement of tree species and tree genetics. They often rely on seed zones established in the 1970s based on historical climate conditions, not future ones—even though up-to-date guidelines for moving species under a warming climate are becoming available. Additionally, much forest policy and research has been framed around species important for timber production—rather than efforts to diversify species and climate-adapted seed-sourcing.

The team of scientists suggest that expanded federal and state investment will be needed to boost both public tree nurseries and seed collection efforts. “This strategy may stimulate production from private nurseries once a stable demand is apparent,” they write. In 2023, the federal government made an investment of $35 million in expanding federal nursery capacity. “However, given the existing (and growing) reforestation backlog, declines in nursery infrastructure, and complex needs for diverse seeds and seedlings, it is likely that substantially more public investment in the form of grants, loans, and cost-share programs will be needed to reinvigorate, diversify, and expand forest nurseries,” they write.

“People want trillions of trees,” says the University of Vermont’s Peter Clark, “but often, on the ground, it’s one old farmer walking around to collect acorns. There’s a massive disconnect.”

University of Vermont forest scientists Peter Clark and Tony D'Amato at an experimental forest in Vemont. They led new research showing a troubling bottleneck that could threaten efforts to fight climate change with tree planting: U.S. tree nurseries don’t grow close to enough trees—nor have the species diversity needed—to meet ambitious planting goals.
CREDIT
Joshua Brown/UVM

JOURNAL

BioScience

DOI

10.1093/biosci/biad049

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

A lack of ecological diversity in forest nurseries limits the achievement of tree-planting objectives in response to global change

ARTICLE PUBLICATION DATE

31-Jul-2023

How heat treatment affects a milk alternative made from rice and coconut water

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

How heat treatment affects a milk alternative made from rice and coconut water — IMAGE: THIS BEVERAGE WITH 5% RICE FLOUR IN COCONUT WATER (LEFT) BECAME SLIGHTLY DARKER AND STICKIER AFTER BEING TREATED WITH HEAT (RIGHT). view more
CREDIT: DIANA C. CASTRO-RODRÍGUEZ

Whether they’re made from soybeans, almonds, oats, or just sourced straight from the cow, milk products must go through heat treatment to prevent harmful bacterial growth and keep them safe. But understanding how these processes affect new, plant-based milk formulations could make the beverages more pleasant to drink as well. Researchers reporting in ACS Omega have discovered how pasteurization and sterilization affects the look and feel of one such drink made from coconut and rice.

Despite the ubiquity of dairy-based foods, many people have some form of lactose intolerance — up to 36% of Americans, according to the National Institutes of Health. As a result, many turn to lactose-free, plant-based alternatives, some of which have added health benefits. For example, one drink under development combines rice flour and coconut water: Rice is hypoallergenic and high in fiber, and coconut water is hydrating and low in calories. To understand how heat treatment might alter this beverage, Jorge Yáñez-Fernández, Diana Castro-Rodríguez and colleagues wanted to test the formulation against two different high-temperature processing steps.

The team used three versions of the beverage, containing either 2%, 5% or 8% rice flour, with coconut water comprising the rest. These were heated either by pasteurization in a water bath at 140 degrees Fahrenheit or by sterilization in an autoclave at almost 250 degrees Fahrenheit. After these treatments, the team found that the starches in the rice flour gelatinized and underwent the Maillard reaction, producing a slightly darkened color and stickier fluid for all three versions. Additionally, the drinks’ acidities increased, and there were fewer sugars, which may alter the way they taste. The team plans to use these results to inform future research into similar, dairy-free, “functional beverages,” including those that could one day contain probiotic, lactic-acid bacteria.

The authors acknowledge funding from the Instituto Politecnico Nacional of Mexico.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

JOURNAL

ACS Omega

DOI

10.1021/acsomega.3c01761

ARTICLE TITLE

“Role of Thermal Process on the Physicochemical and Rheological Properties and Antioxidant Capacity of a New Functional Beverage Based on Coconut Water and Rice Flour”

ARTICLE PUBLICATION DATE

28-Jul-2023

Plant-based protein intake may reduce kidney disease risk

Peer-Reviewed Publication

NATIONAL KIDNEY FOUNDATION

Plant-based diets confer various health benefits, including lowering the risk of cardiovascular disease and certain cancers. However, the relationship between plant protein intake and the risk of chronic kidney disease (CKD) remains unclear. This study led by Ga Young Heo aimed to investigate the association between plant protein intake and the development of CKD. Using the UK biobank study data, the researchers found that participants with a higher plant protein intake had a lower risk of developing CKD. This finding suggests that a higher dietary intake of plant-based protein may be beneficial for kidney health and provide insight into dietary interventions to prevent CKD in primary care settings.

ARTICLE TITLE: Association of Plant Protein Intake With Risk of Incident CKD: A UK Biobank Study

AUTHORS: Ga Young Heo, MD, Hee Byung Koh, MD, Hyo Jeong Kim, MD, Kyung Won Kim, MD, Chan-Young Jung, MD, Hyung Woo Kim, MD, Tae Ik Chang, MD, PhD, Jung Tak Park, MD, PhD, Tae-Hyun Yoo, MD, PhD, Shin-Wook Kang, MD, PhD, and Seung Hyeok Han, MD, PhD

DOI: 10.1053/j.ajkd.2023.05.007

JOURNAL

American Journal of Kidney Diseases

DOI

10.1053/j.ajkd.2023.05.007

ARTICLE TITLE

Association of Plant Protein Intake With Risk of Incident CKD: A UK Biobank Study

ARTICLE PUBLICATION DATE

28-Jul-2023

Lignin separation method could make renewable material profitable

Peer-Reviewed Publication

WASHINGTON STATE UNIVERSITY

RICHLAND, Wash. – A novel method to extract lignin could help spin wheat straw into gold. Lignin produced using the new method was color-neutral, odorless and homogenous, an advance that could make this carbon-neutral material a more viable candidate for development of high-value products.

Reporting in the Proceedings of the National Academy of Sciences, the Washington State University researchers extracted up to 93% lignin with up to 98% purity from wheat straw, producing a significant amount of material in a uniform way that could make it more attractive for industry use.

“This method allows us to extract lignin from plant material in its native form and at a high yield,” said Xiao Zhang, professor in WSU’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering, who led the work. “We were able to demonstrate to industry that it is possible to make color-neutral and odorless lignin, and we can make quite a bit of the material to begin evaluating its applications.”

Lignin is the second most abundant renewable carbon source, making up about 30% of the non-fossil fuel-based carbon on Earth. It is in all vascular plants, where it forms cell walls and provides plants with rigidity. Lignin allows trees to stand, gives vegetables their firmness and makes up about 20%-35% of the weight of wood. The material holds great promise as a precursor for biobased materials and fuels, but it is also notoriously difficult to extract from plants.

The material is usually separated during papermaking and biorefining, but these processes often contaminate and significantly alter lignin’s chemical and physical properties, decreasing its value. So most lignin is either burned to produce fuel and electricity or used in low-value products, such as for cement additives or as a binder in animal feed. Producing a more homogenous lignin provides the opportunity to pursue high-value material development to replace petroleum-derived plastics and polymers.

“Because of its heterogeneity, lignin can’t be used as a valuable material despite centuries of effort,” said Zhang, who holds a joint appointment with Pacific Northwest National Laboratory. “The saying has been that ‘you can make anything out of lignin, except money.’ There’s so much heterogeneity in the molecules that nobody can reliably make things out of it.”

In their work, the researchers used a solvent to separate the lignin from wheat straw and were able to preserve and control its key properties, producing a more uniform molecule with a consistent molecular weight that makes it more useful for industry. The lignin extracted was light-colored, which is more like the lignin that exists in nature.

Because it is an electron-rich compound, the lignin had a strong affinity for the solvent, and the electron interactions allowed the researchers to extract it with minimal chemical reactions, which protected its natural molecular structure that is so often easily damaged in chemical separations.

WSU’s Office of Commercialization has filed a provisional patent and will assist the researchers for the scale-up and eventual commercialization of this technology. To make it more viable for industry applications, the research team is working to decrease the lengthy processing time and the amount of purification chemicals needed.

The work was done in collaboration with Edoardo Apra, a computational scientist from PNNL, and Professor Art Ragauskas from University of Tennessee, Knoxville. It was supported by the National Science Foundation and the U.S. Department of Agriculture National Institute of Food and Agriculture as well as WSU’s Commercialization Gap fund.

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2307323120

ARTICLE TITLE

Lignin with controlled structural properties by N-heterocycle-based deep eutectic solvent extraction

ARTICLE PUBLICATION DATE

4-Aug-2023

MIT engineers create an energy-storing supercapacitor from ancient materials

Made of cement, carbon black, and water, the device could provide cheap and scalable energy storage for renewable energy sources

ANCIENT PEOPLES COULD HAVE DONE THIS

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Cement supercapacitor — IMAGE: SINCE THE NEW “SUPERCAPACITOR” CONCRETE WOULD RETAIN ITS STRENGTH, A HOUSE WITH A FOUNDATION MADE OF THIS MATERIAL COULD STORE A DAY’S WORTH OF ENERGY PRODUCED BY SOLAR PANELS OR WINDMILLS, AND ALLOW IT TO BE USED WHENEVER IT’S NEEDED. view more
CREDIT: IMAGE COURTESY OF FRANZ-JOSEF ULM, ADMIR MASIC, AND YANG-SHAO HORN

CAMBRIDGE, Mass. -- Two of humanity's most ubiquitous historical materials, cement and carbon black (which resembles very fine charcoal), may form the basis for a novel, low-cost energy storage system, according to a new study. The technology could facilitate the use of renewable energy sources such as solar, wind, and tidal power by allowing energy networks to remain stable despite fluctuations in renewable energy supply.

The two materials, the researchers found, can be combined with water to make a supercapacitor — an alternative to batteries — that could provide storage of electrical energy. As an example, the MIT researchers who developed the system say that their supercapacitor could eventually be incorporated into the concrete foundation of a house, where it could store a full day’s worth of energy while adding little (or no) to the cost of the foundation and still providing the needed structural strength. The researchers also envision a concrete roadway that could provide contactless recharging for electric cars as they travel over that road.

The simple but innovative technology is described in a forthcoming paper in the journal PNAS, in a paper by MIT professors Franz-Josef Ulm, Admir Masic, and Yang-Shao Horn, and four others at MIT and at the Wyss Institute.

Capacitors are in principle very simple devices, consisting of two electrically conductive plates immersed in an electrolyte and separated by a membrane. When a voltage is applied across the capacitor, positively charged ions from the electrolyte accumulate on the negatively charged plate, while the positively charged plate accumulates negatively charged ions. Since the membrane in between the plates blocks charged ions from migrating across, this separation of charges creates an electric field between the plates, and the capacitor becomes charged. The two plates can maintain this pair of charges for a long time and then deliver them very quickly when needed. Supercapacitors are simply capacitors that can store exceptionally large charges.

The amount of power a capacitor can store depends on the total surface area of its conductive plates. The key to the new supercapacitors developed by this team comes from a method of producing a cement-based material with an extremely high internal surface area due to a dense, interconnected network of conductive material within its bulk volume. The researchers achieved this by introducing carbon black — which is highly conductive — into a concrete mixture along with cement powder and water, and letting it cure. The water naturally forms a branching network of openings within the structure as it reacts with cement, and the carbon migrates into these spaces to make wire-like structures within the hardened cement. These structures have a fractal-like structure, with larger branches sprouting smaller branches, and those sprouting even smaller branchlets, and so on, ending up with an extremely large surface area within the confines of a relatively small volume. The material is then soaked in a standard electrolyte material, such as potassium chloride, a kind of salt, which provides the charged particles that accumulate on the carbon structures. Two electrodes made of this material, separated by a thin space or an insulating layer, form a very powerful supercapacitor, the researchers found.

The two plates of the capacitor function just like the two poles of a rechargeable battery of equivalent voltage: When connected to a source of electricity, as with a battery, energy gets stored in the plates, and then when connected to a load, the electrical current flows back out to provide power.

“The material is fascinating,” Masic says, “because you have the most-used manmade material in the world, cement, that is combined with carbon black, that is a well-known historical material — the Dead Sea Scrolls were written with it. You have these at least two-millennia-old materials that when you combine them in a specific manner you come up with a conductive nanocomposite, and that’s when things get really interesting.”

As the mixture sets and cures, he says, “The water is systematically consumed through cement hydration reactions, and this hydration fundamentally affects nanoparticles of carbon because they are hydrophobic (water repelling).” As the mixture evolves, “the carbon black is self-assembling into a connected conductive wire,” he says. The process is easily reproducible, with materials that are inexpensive and readily available anywhere in the world. And the amount of carbon needed is very small — as little as 3 percent by volume of the mix — to achieve a percolated carbon network, Masic says.

Supercapacitors made of this material have great potential to aid in the world’s transition to renewable energy, Ulm says. The principal sources of emissions-free energy, wind, solar, and tidal power, all produce their output at variable times that often do not correspond to the peaks in electricity usage, so ways of storing that power are essential. “There is a huge need for big energy storage,” he says, and existing batteries are too expensive and mostly rely on materials such as lithium, whose supply is limited, so cheaper alternatives are badly needed. “That’s where our technology is extremely promising, because cement is ubiquitous,” Ulm says.

The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household. Since the concrete would retain its strength, a house with a foundation made of this material could store a day’s worth of energy produced by solar panels or windmills and allow it to be used whenever it’s needed. And, supercapacitors can be charged and discharged much more rapidly than batteries.

After a series of tests used to determine the most effective ratios of cement, carbon black, and water, the team demonstrated the process by making small supercapacitors, about the size of some button-cell batteries, about 1 centimeter across and 1 millimeter thick, that could each be charged to 1 volt, comparable to a 1-volt battery. They then connected three of these to demonstrate their ability to light up a 3-volt light-emitting diode (LED). Having proved the principle, they now plan to build a series of larger versions, starting with ones about the size of a typical 12-volt car battery, then working up to a 45-cubic-meter version to demonstrate its ability to store a house-worth of power.

There is a tradeoff between the storage capacity of the material and its structural strength, they found. By adding more carbon black, the resulting supercapacitor can store more energy, but the concrete is slightly weaker, and this could be useful for applications where the concrete is not playing a structural role or where the full strength-potential of concrete is not required. For applications such as a foundation, or structural elements of the base of a wind turbine, the “sweet spot” is around 10 percent carbon black in the mix, they found.

Another potential application for carbon-cement supercapacitors is for building concrete roadways that could store energy produced by solar panels alongside the road and then deliver that energy to electric vehicles traveling along the road using the same kind of technology used for wirelessly rechargeable phones. A related type of car-recharging system is already being developed by companies in Germany and the Netherlands, but using standard batteries for storage.

Initial uses of the technology might be for isolated homes or buildings or shelters far from grid power, which could be powered by solar panels attached to the cement supercapacitors, the researchers say.

Ulm says that the system is very scalable, as the energy-storage capacity is a direct function of the volume of the electrodes. “You can go from 1-millimeter-thick electrodes to 1-meter-thick electrodes, and by doing so basically you can scale the energy storage capacity from lighting an LED for a few seconds, to powering a whole house,” he says.

Depending on the properties desired for a given application, the system could be tuned by adjusting the mixture. For a vehicle-charging road, very fast charging and discharging rates would be needed, while for powering a home “you have the whole day to charge it up,” so slower-charging material could be used, Ulm says.

“So, it’s really a multifunctional material,” he adds. Besides its ability to store energy in the form of supercapacitors, the same kind of concrete mixture can be used as a heating system, by simply applying electricity to the carbon-laced concrete.

Ulm sees this as “a new way of looking toward the future of concrete as part of the energy transition.”

The research team also included postdocs Nicolas Chanut and Damian Stefaniuk at MIT’s Department of Civil and Environmental Engineering, James Weaver at the Wyss Institute for Biologically Inspired Engineering, and Yunguang Zhu in MIT’s Department of Mechanical Engineering. The work was supported by the MIT Concrete Sustainability Hub, with sponsorship by the Concrete Advancement Foundation.

MIT engineers have created a “supercapacitor” made of ancient, abundant materials, that can store large amounts of energy. Made of just cement, water, and carbon black (which resembles powdered charcoal), the device could form the basis for inexpensive systems that store intermittently renewable energy, such as solar or wind energy.

CREDIT

Image courtesy of Franz-Josef Ulm, Admir Masic, and Yang-Shao Horn

Written by David L. Chandler, MIT News Office

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2304318120

ARTICLE TITLE

Carbon–cement supercapacitors as a scalable bulk energy storage solution

ARTICLE PUBLICATION DATE

31-Jul-2023

How to distinguish slow and fast earthquakes

New data analysis bolsters a controversial law defining the scale of slow earthquakes, allows reinterpretation, and offers a potential for forecasting fast earthquakes.

Peer-Reviewed Publication

SCHOOL OF SCIENCE, THE UNIVERSITY OF TOKYO

The difference between slow and fast earthquakes — IMAGE: WHILE FAST EARTHQUAKES ARE VIOLENT SHAKES LASTING FOR A FEW MINUTES, SLOW EARTHQUAKES ARE SUBDUED SHAKES LASTING SEVERAL DAYS. UNDERSTANDING SLOW EARTHQUAKES MIGHT HELP FORECAST FAST EARTHQUAKES. view more
CREDIT: IMAGE MODIFIED FROM “SCIENCE OF SLOW EARTHQUAKES” LEAFLET. HTTPS://WWW.ERI.U-TOKYO.AC.JP/PROJECT/SLOWEQ/EN/NEWSLETTERS/PDF/LEAFLET_EN.PDF

Researchers from the University of Tokyo and Stanford University show what differentiates slow and fast earthquakes and how their magnitudes vary with time.

Normally, earthquakes last up to a few minutes and radiate strong seismic waves. But around 23 years ago, scientists discovered an unusual slow-slip phenomena called slow earthquakes. Slow earthquakes last days or even months. Though they involve significant tectonic movement, you may never feel them. Since slow earthquakes could indicate future fast earthquakes, monitoring and understanding them helps accurately forecast devastating earthquakes and tsunamis.

Understanding them requires knowing how they change over time. For that, researchers use scaling laws which define the relationship between two quantities over a wide interval. In 2007, researchers proposed a controversial scaling law relating the magnitude and duration of earthquakes, which can help differentiate slow and fast earthquakes.

According to the scaling law, for slow earthquakes, as its magnitude (measured by a quantity called seismic moment) increases, the duration of the earthquake increases proportionately. For fast earthquakes, the relation is not linearly but cubically proportionate, which means the seismic moment increases very rapidly in a short time.

The scaling law received criticism from other researchers and raised questions about the likelihood of events in between slow and fast earthquakes that do not fall within the law. Seismologists Satoshi Ide of the University of Tokyo and Gregory Beroza of Stanford University now bolster the scaling law with more data, reinterpret the scaling relation, and address the controversy.

“Most of the challenges to the scaling law were problematic, but we have had no chance to disprove their challenges,” says Ide. “A surprise was that totally erratic results were published in Nature, and believed by many scientists, who made further problematic numerical models.”

With the advent of new seismic detection technology and data accumulated over 16 years, Ide and Beroza now reason that most arguments against the law had improper data calculations and were inconsistent given their data constraints. They suggest the presence of a speed limit to slow earthquakes and reveal physical processes that differentiate slow and fast earthquakes.

Many, but all the same

Since slow earthquakes include phenomena with different frequency bands, they are more diverse than fast earthquakes. They were named differently, such as low-frequency earthquakes, tectonic tremors, very low-frequency earthquakes, and slow slip events. So researchers observing one type of slow earthquake considered other types irrelevant. “Our study confirmed that all these phenomena are mutually connected, or rather regarded as a single phenomenon that radiates various signals,” explains Ide.

Slow slips, but not so fast

Slow earthquakes are so subtle and inaccessible that detecting and monitoring them is challenging. Due to the detection bias, only large enough slow earthquakes are observed. That prompted Ide and Beroza to propose an upper limit to the speed of slow earthquakes. Based on that, the duo redefined the 2007 scaling law with the maximum value constraint. As they showed continuous evidence for the scaling law over a broad time scale of less than a second to more than a year, they put an end to the debate.

How are slow and fast earthquakes different?

When Ide’s group proposed the scaling law in 2007, they were unsure of what makes these two earthquake types different. Now, with more data and theoretical models, Ide and Beroza show that their scaling differences dictate physical movement processes governing the events. Diffusion processes govern slow earthquakes, whereas seismic wave propagation dictates fast earthquakes. Because of this difference, the magnitude of slow earthquakes cannot be as large as fast earthquakes when the event lasts longer.

“We pointed out that ‘diffusion’ is important in slow earthquakes, but what is physically diffusing is not well understood,” says Ide.

Experts still don't know what kind of forecast information they can provide based on slow earthquake monitoring. This study will be a foundation for building appropriate numerical models, making predictions, and taking countermeasures.

###

Useful resources for journalists:

A leaflet explaining slow and fast earthquakes:

https://www.eri.u-tokyo.ac.jp/project/sloweq/en/newsletters/pdf/leaflet_EN.pdf

About the School of Science, the University of Tokyo: https://www.s.u-tokyo.ac.jp/en/overview/
Researcher website: http://www-solid.eps.s.u-tokyo.ac.jp/~ide/en/
About the project: https://en.slow-to-fast-eq.org/project-overview/

How slow and fast earthquakes differ in their scaling

They differ in the duration and the magnitude of the quake. Data from slow earthquakes from three well-known earthquakes regions, Nankai, Cascadia, and Mexico, are highlighted in different colors.
CREDIT
Ide and Beroza, 2023.

Journal article: Satoshi Ide and Gregory Beroza. 2023. Slow earthquake scaling reconsidered as a boundary between distinct modes of rupture propagation. PNAS.

JOURNAL

Proceedings of the National Academy of Sciences

METHOD OF RESEARCH

Data/statistical analysis

ARTICLE TITLE

Slow earthquake scaling reconsidered as a boundary between distinct modes of rupture propagation

ARTICLE PUBLICATION DATE

31-Jul-2023

Holding Trump accountable will not threaten American democracy

Reports and Proceedings

UNIVERSITY OF PENNSYLVANIA

With a Fulton County indictment of former President Donald Trump possible at any time, law enforcement in Atlanta is bracing for potential violence, with orange barricades restricting access to the entrance of the county courthouse.

With the anticipation of each new indictment has come threats of violence, decrease in trust in American justice and calls for retribution against the government. Just how concerned should Americans be that we may face another January 6th-type incident?

New data from the Polarization Research Lab — a collaboration among researchers at Dartmouth College, the University of Pennsylvania, and Stanford University — has found that despite rhetoric from Trump and his allies, the public do not see the indictment of a former president as a reason to abandon democratic principles or as a call to support violent retribution.

During the study — conducted by lab Co-Directors Yphtach Lelkes, Associate Professor of Communication at the Annenberg School for Communication at the University of Pennsylvania; Sean J. Westwood, Associate Professor of Government at Dartmouth College; and Derek Holliday, postdoctoral fellow with the lab, based at Stanford University — the researchers tracked public attitudes among Americans toward democratic norms, political violence, and general partisan hatred.

For nearly a year, they performed daily tracking polls with nearly 30,000 survey interviews.

What they found is that 97% of Americans — from both parties — oppose political violence, and the majority disapprove when politicians violate political norms.

Reacting to the June 12 Indictments

Support for political violence remained stable before and after the June 12 federal indictment of Trump and co-defendant Walt Naruta, with most Americans rejecting even non-violent acts of protest.

Following the indictment, both Democrats and Republicans felt a surge of positive regard for their own parties, but this effect lasted only a week, and each party’s dislike of the other remained unchanged.

The indictments on June 12 did increase Republican appetites for violating political norms, but it was fleeting, and driven largely by a four percentage point rise in the desire to censor news networks that were, in their view, unfair to their party.

The effect vanished after seven days, and by the end of June, Republicans were less supportive of norm violations relative to the period before the indictment.

A Fractured America

Trump’s indictments did not permanently change American attitudes on democracy, but real threats remain.

“Trump rose to power in a fractured America and while he contributed to divides, they existed before his presidency and will continue in the years to come,” Lelkes says.

The researchers’ data shows that the majority of everyday Americans have no positive views of the opposing party, don’t trust their politicians, don’t feel their government is responsive to their needs, and nearly a majority support at least one democratic norm violation.

It remains possible that the short-lived trends observed in their data could trigger mob behavior similar to what happened on January 6th, they say.

But critically, the overwhelming majority of Americans would reject both violence and an attack on democratic norms.

“As much as American politics can be crude and juvenile, when it comes to support for democracy itself, our data show that Americans are remarkably adult-like,” Lelkes says.

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Holding Trump Accountable Has Not Threatened American Democracy

ARTICLE PUBLICATION DATE

28-Jul-2023