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Publication date: 1 April 2025

Source: Advances in Space Research, Volume 75, Issue 7

Author(s): Kiran, Ravindra P. Singh

Publication date: 1 April 2025

Source: Advances in Space Research, Volume 75, Issue 7

Author(s): Tsung-Yu Wu, Jann-Yenq Liu

Publication date: 1 April 2025

Source: Advances in Space Research, Volume 75, Issue 7

Author(s): İlkin Özsöz, Oya Ankaya Pamukçu

Identifying long-term seismic activity patterns is crucial for understanding how fault systems evolve, as well as for estimating the probability of future earthquakes. But seismic records date back only hundreds of years—1,000 years at the most—not long enough to fully understand any given fault's history.

Depleted groundwater threatens communities, agriculture, and ecosystems in California's Central Valley, which produces much of the nation's fruit, vegetables, and nuts. But the same acres where farmers have long cultivated thirsty crops might be critical for refilling aquifers, Stanford scientists have found.

body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news regarding law and policy changes that impact science and scientists today.

NOAA has quietly reported that they will soon decommission 14 datasets, products, and catalogs related to earthquakes and marine, coastal, and estuary science. According to the list, these data sources will be “decommissioned and will no longer be available” by early- to mid-May.

Though NOAA regularly evaluates its data products to ensure they are still relevant, data sources are usually merged with or replaced by other products rather than outright removed. The agency did this just 7 times in 2024 and 6 times in 2023.

 
Related

• NOAA’s Notice of Changes (16 April 2025)
•  Environmental and Science Groups Sue Trump Admin for Deleting Environmental Justice and Climate Information From Federal Agency Websites (EcoWatch)
•  Get Involved: AGU Science Policy Action Center
 

On social media, scientists are urging their colleagues to access and download these data before they are removed so that scientific analyses can continue and the value of the data is not lost.

The announcement of the removals comes days after environmental and science groups sued the Trump administration for the removal of climate and environmental justice websites and data.

“The public has a right to access these taxpayer-funded datasets,” Gretchen Goldman, president of the Union of Concerned Scientists, said in a statement about the lawsuit. “From vital information for communities about their exposure to harmful pollution, to data that help local governments build resilience to extreme weather events, the public deserves access to federal datasets. Removing government datasets is tantamount to theft.”

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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When Julian Lozos visited the site of the 2019 Ridgecrest earthquakes two days after the event, he noticed something strange. Pebble- to boulder-sized rocks had clearly been moved by the earthquakes—but there were no signs of dragging or shearing on the desert ground.

The Colorado River system is the lifeblood of the southwest, delivering water to 40 million people across the United States and Mexico. Drought and overuse have left the river in crisis—the need for water far exceeds what's available.

In a few weeks, Earth scientists will launch a satellite that will provide unprecedented, high-resolution coverage of some of the most remote and rapidly changing parts of the world. The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, a joint mission between NASA and the Indian Space Research Organisation (ISRO), will scan nearly the entire globe twice every 12 days to measure changes in Earth’s ecosystems, cryosphere, and land surface.

“In my eyes, it’s orbiting magic,” said Alex Gardner, a glaciologist at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., and a member of NISAR’s cryosphere science team. NISAR will provide high-resolution radar imagery that will enable scientists to track glaciers and ice, biodiversity, soil moisture and water placement, and land displacements from events like earthquakes and landslides.

“When there’s an earthquake, and you can see displacements from 500 kilometers up that you wouldn’t even be able to notice if you were standing on the ground…that’s orbiting magic,” Gardner said.

Double Radar

NISAR is currently anticipated to launch in June from the Satish Dhawan Space Centre in India. It will be the largest, but not the first, satellite collaboration between NASA and ISRO, explained Paul Rosen, NISAR project scientist at JPL. “We had some other collaborations in both planetary and Earth science, but not at this level of magnitude,” he said.

The satellite will host two synthetic aperture radar (SAR) systems that operate at different microwave wavelengths, one longer (L band, at a wavelength of 24 centimeters) and one shorter (S band, at a wavelength of 10 centimeters). SAR is a technique used to create high-resolution images from lower-resolution instruments. The instruments emit continuous pulses of microwave radiation and use the light that bounces back, as well as the time delay, to create backscatter images.

“We made sure that the two radars could work together,” Rosen said. “They’re highly in sync, and we can turn them on together or operate them separately.”

“It’s got a lot to deliver on, but I don’t feel that nervous about it.”

Unlike visible-light imaging, SAR is not limited by the time of day or the weather, explained Deepak Putrevu, an engineer and colead of NISAR’s ISRO science team at the Space Applications Centre in Ahmedabad, India. “It uses microwaves for imaging, so that that makes it able to penetrate the clouds and to image even during the nighttime.…The SAR technology enables us to have day and night coverage and all-weather imaging capability.”

NISAR’s orbit will cause it to pass over the same locations every 12 days. Because SAR can map an area both as it approaches (ascending orbit) and departs (descending orbit), NISAR will be able to scan each area twice every 12 days. Each space agency provided one of the radar systems, as well as other components of the satellite, the launch system, and the data management infrastructure.

“We jointly operate the mission and jointly do the science,” Rosen added.

“It’s got a lot to deliver on, but I don’t feel that nervous about it,” Gardner said. “Aspects of these technologies have flown before,” he added. For example, the European Space Agency’s Sentinel satellites carry SAR instruments that have helped scientists understand the cryosphere, Earth surface processes, and ecosystems. But NISAR’s dual radar frequency bands are a first for Earth-observing satellites. The systems will be able to detect changes at different physical scales—L band for large structures and S band for smaller ones—as well as provide higher-resolution images together than can be achieved individually.

Global Surface Changes

One of NISAR’s primary science objectives is to observe changes to the cryosphere and glaciers around the world. That’s Gardner’s wheelhouse.

“Glaciers are just these really fantastic living creatures,” he said. NISAR will monitor seasonal growth and retreat patterns of glaciers around the world, with a special focus on those of the West Antarctic Ice Sheet like Pine Island and Thwaites.

On 23 January, a large iceberg broke away from Antarctica’s Brunt Ice Shelf. NISAR’s orbit will help glaciologists monitor Earth’s rapidly changing cryosphere. Credit: Contains modified Copernicus Sentinel data (2023), processed by ESA, CC BY-SA 3.0 IGO

“They just have such large societal consequence that there’ll be a lot of attention there,” Gardner explained. More broadly, he said, those seasonal patterns can be a good predictor of long-term changes in the cryosphere.

NISAR will also be able to observe the vertical displacements of ice sheets, which Gardner said will allow cryosphere scientists to map where floating ice sheets meet grounded ice, a boundary called the grounding line.

“It’s really hard to measure, and it’s been done locally but not really at large scale,” he said. “We can watch that position of that grounding line change with time, which is an indicator of vulnerability” to warming temperatures.

NISAR will also measure global biodiversity and soil moisture. The two radar frequency bands will be especially helpful with this, Putrevu explained. “With forest biomass, the L-band system will be able to see the dense forest with more sensitivity. But when we use the S-band system, you can use it for sparse vegetation, as well.”

The SAR systems will be able to see through crop cover and measure soil moisture, Putrevu added, which will provide key information for farmers and agribusiness. He also highlighted the importance of closely monitoring changes in land deformation, which might suggest imminent earthquakes or landslides.

“All the applications have a societal benefit attached,” Putrevu said. “It gives a great deal of satisfaction that this will actually be useful for society.”

NISAR will map Earth’s global land biomass twice every 12 days. Credit: NASA/JPL-Caltech, Public Domain A Data Deluge

After launch, it will take 90 days for the satellite to conduct its commissioning tests and reach its science orbit. “But as we progress, we’re going to get little peeks behind the curtains that we are going to be so enthusiastic about as we see the imagery start to really mature, and the data processing mature, the data acquisition mature,” Gardner explained. “There’ll be a progression from a first light image to science ready data.”

Every pass of the satellite will provide an order of magnitude more data than past satellites have delivered. Much of the final preparation before launch has involved developing the infrastructure needed to efficiently receive, process, and make available such large quantities of data.

“The sheer volume of new data that we’re going to be dealing with requires the development of novel tools.”

“Once NISAR comes online, the sheer volume of new data that we’re going to be dealing with requires the development of novel tools,” Gardner said. “NISAR is really leaning into cloud architecture” for data storage, availability, and computing, so that users don’t have to download massive quantities of data to individual servers. “Moving data around is one of the largest bottlenecks with missions like this.”

“We have been preparing for the last couple years to get all of our algorithms working really efficiently in the cloud,” Gardner said, “so that when the fire hose of data comes online, we can get in there, plug into that data stream, and benefit from it really early on.”

Putrevu said that scientists and students across India have been participating in workshops since 2014 to learn how to access, process, and produce science from NISAR’s data. “That shows how the community is getting geared up to use the data,” he said. “Everyone is eagerly looking forward to [launch] day.”

Because the volume of information requires such novel processing tools, Gardner cautioned that it might be a year or two before NISAR data yield new scientific outcomes. The mission’s nominal lifetime is 3 years, and once the analysis gets up to speed, discoveries derived from those data will likely continue for decades.

“Without a doubt, it will be a legacy dataset,” Gardner said. “It’s going to be transformational.”

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

Correction 22 April 2025: NISAR’s launch date has been updated.

Citation: Cartier, K. M. S. (2025), “Transformational” satellite will monitor Earth’s surface changes, Eos, 106, https://doi.org/10.1029/2025EO250140. Published on 17 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

From cracking mud to thawing permafrost, fractured terrain is common on Earth and many planetary surfaces. And the geometry of those fractures is influenced by both the presence of water and how long it’s been around, according to researchers. A team has now proposed a model to predict the evolution of fractured terrain through time. These new findings could be used to unravel the history of water on other worlds.

Since the 1960s, spacecraft and landers have been beaming back observations of various solar system bodies, returning hundreds of thousands of images. “The amount of data coming in is overwhelming, and it is mostly pictures,” said Gábor Domokos, an applied mathematician at the Budapest University of Technology and Economics in Hungary.

“From the moment that materials solidify, they start falling apart.”

Many of those images show a process now known to be ubiquitous across the solar system: disintegration. “From the moment that materials solidify, they start falling apart,” said Doug Jerolmack, a geophysicist at the University of Pennsylvania in Philadelphia. The study that Domokos and Jerolmack and their respective graduate students Krisztina Regős and Sophie Silver recently published in the Proceedings of the National Academy of Sciences of the United States of America reflects that sentiment in a poetic first line: “Things fall apart.”

The researchers analyzed images of fractured terrain on Venus, Mars, and Jupiter’s moon Europa and manually traced fractures visible in each. The team focused on 15 images: 4 of Venus, 9 of Mars, and 2 of Europa.

From above, the fracture networks look like mosaics of convex polygons. Those polygons can be characterized by simple geometric properties, including their number of vertices and the number of cracks that meet at each of those vertices (or “nodes”). The team did just that, and there was nothing particularly complicated about that work, Domokos said. “We are just counting.”

Of the more than 13,000 nodes that the researchers tabulated, more than 95% consisted of the meeting of two, three, or four cracks. Previous work in geomorphology has referred to those intersections as T, Y, and X junctions, respectively, on the basis of the letters that they often resemble.

Three Letters, Three Processes

T junctions were the most prevalent in the imagery. That result is consistent with investigations of fractures on Earth and not surprising, Jerolmack said, because these junctions form from a basic process: a newer crack running into an older crack and stopping. “This is the most common pattern of something that just breaks and breaks and breaks,” Jerolmack explained. A mud plain that was once wet and then dried over time would be dominated by T junctions.

Y junctions, on the other hand, were less common and tended to occur in landforms that had experienced alternating periods of drying and wetting, the team showed. Laboratory results support that finding: In 2010, another research group published time-lapse photography of clay undergoing repeated cycles of drying and wetting and uncovered T junctions evolving into Y junctions.

The propagation of a crack through partially, but not fully, healed T junctions tends to produce rounded corners, said Lucas Goehring, a physicist at Nottingham Trent University in the United Kingdom and the lead author of that study. “Over time, that corner will be dragged into a shape that is like a Y.”

Though Y junctions do not necessarily imply the presence of water—these features also form in basalt columns, for instance—they hint that a landscape might have experienced a sustained presence of water, according to the researchers.

X junctions proved to be the rarest of the three. The team spotted X junctions—in which a newer crack runs right through an older crack—only on Europa. “Normally, a crack cleanly separates two surfaces,” Goehring said. But an X junction is evidence that a previous crack healed, thereby allowing a younger crack to propagate across it largely unimpeded. “It’s behaving as if that old crack isn’t there,” Jerolmack said.

Water ice is one such material that heals itself, and Europa is known to be covered in a shell of the stuff. Spotting X junctions implies the presence of frozen water, the researchers concluded.

Making Movies

“We don’t have these kinds of movies, not even on Earth.”

Domokos, Jerolmack, and their students next constructed a geometrical model of fracturing. The goal was to develop mathematical expressions encoding the physical processes involved in forming T, Y, and X junctions and then, on the basis of a single image of a planetary surface, model how an ensemble of fractures would evolve over time.

Playing such a movie back might reveal something about the geological processes underlying crack formation, Domokos said. That’s powerful for understanding not only our own planet but other worlds as well. “We don’t have these kinds of movies, not even on Earth.”

The researchers showed that their model could accurately reproduce the entire range of fracture mosaics they observed. That’s critical to verifying the utility of this model, Jerolmack said. “We built a toy model of the universe of fracturing. The actual universe of crack patterns seems happy to comply.”

Testing this model will require more experimental data showing how real fractures evolve, however, Goehring said. Collecting such data isn’t technically challenging, but it can be laborious: Goehring and his team spent several months observing how clay fractured in response to 25 cycles of drying and wetting. “It’s quite a tedious experiment to do,” he said.

But such a model could shed important light on the solar system’s past, said Nina Lanza, a planetary scientist at Los Alamos National Laboratory in New Mexico who was not involved in the research. For instance, getting a handle on whether water persisted somewhere for a long time says something about the geological environment, she said. “Now we’re getting a more complex picture of a planet over time.”

Domokos, Jerolmack, and their students analyzed all of their fracture mosaics manually. However, future investigations could rely on artificial intelligence and machine learning, which would make it possible to probe not just a handful of fracture mosaics but, instead, thousands.

—Katherine Kornei (@KatherineKornei), Science Writer

Citation: Kornei, K. (2025), Cracks on planetary surfaces hint at water, Eos, 106, https://doi.org/10.1029/2025EO250146. Published on 17 April 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Tectonics

Identifying long-term seismic activity patterns is crucial for understanding how fault systems evolve, as well as for estimating the probability of future earthquakes. But seismic records date back only hundreds of years—1,000 years at the most—not long enough to fully understand any given fault’s history. Furthermore, because faults can experience times of high activity alternating with quiet periods lasting millennia, seismic forecasts extrapolating from short time spans may greatly over- or underestimate a fault’s rate of activity.

One approach for studying longer-term seismic activity on a fault, chlorine-36 (36Cl) cosmogenic dating, is used to recover histories that can span more than 10,000 years. As slip along a fault progressively exposes rocks, cosmic radiation interacts with carbonate rocks on the fault surface to form atoms of 36Cl, an isotope of chlorine. Concentrations of the isotope reveal approximately how long different rocks have been exposed, a proxy for when earthquakes happened.

Sgambato et al. used 36Cl cosmogenic dating to assess seismic activity over millennia on three faults in Italy’s southern Apennines, where some of the country’s strongest earthquakes have occurred. They then compared the data with other paleoseismic estimates derived from excavating trenches along a fault and tracing markers to measure its displacement. The researchers also calculated slip rates and related annual earthquake probabilities.

The authors found that all three faults experienced periods of both high seismic activity and dormancy in the past 30,000 years and that estimates of earthquake activity from trenching generally agreed with those derived from 36Cl dating. They noted that their results may help show whether these faults are connected to others in the region.

Their research further indicates that slip on a single fault can account for all the regional extension in a given year. This may indicate that strain can be localized to individual faults at certain times. Because their work uncovered a longer record of the clustering of earthquake activity along these faults, it also has implications for seismic hazard forecasting. (Tectonics, https://doi.org/10.1029/2024TC008529, 2025)

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2025), Isotopes unearth history of earthquakes in the Apennines, Eos, 106, https://doi.org/10.1029/2025EO250147. Published on 17 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

SummaryGeomagnetic observations at Eskdalemuir observatory in Southern Scotland reveal reduced amplitudes in the vertical component variations compared with the horizontal components for periods of less than an hour. A subsurface high conductivity feature has previously been suggested to account for this anomaly. However, past studies have overlooked the effect of seasonal source changes and impact of solar activity on external geomagnetic field variations. The vertical magnetic transfer function - referred to as the tipper - relates temporal variation in the vertical magnetic field to those in the horizontal magnetic field and is sensitive to lateral electrical conductivity contrasts in the subsurface. Quantifying the seasonal variations in the tipper helps to identify times when external field variations minimally bias tipper estimates, thereby providing a more accurate representation of subsurface conductivity. Ionospheric current systems, particularly during geomagnetic storms, may violate the plane wave assumption underlying tipper estimation at mid-latitudes. This may allude to a more complex source geometry responsible for magnetic field variations. Our study quantifies and proposes a correction for space weather-driven external field contributions to observations for periods shorter than one hour. Using high-quality digital magnetic field data with a one-minute sampling rate from 2001 to 2019, we estimate the tipper at Eskdalemuir, revealing seasonal differences that increase with periods between 1000 s and 10000 s. After finding that tipper estimates during the 2016 time series are least affected by seasonal effects, we used one-second time series and a simple empirical model to quantify the daily variability of the tipper. The model consists of annual and semi-annual terms plus a term proportional to either the F10.7 cm solar flux or geomagnetic Ap index. Neither model fits the data to within the expected error, but the model that uses Ap has better fit. Tipper estimates from temporary site deployments are affected by these seasonal external variations, and we correct those obtained at sites near Eskdalemuir during a recent field experiment using this model.

The use of solar power is growing rapidly, especially in developing regions in the tropics, as countries work toward meeting carbon neutrality goals. But according to new research, solar power use is also accompanied by solar power shortages (droughts) when demand exceeds supply for at least three days. Such shortages can leave millions without access to cooling or cooking abilities.

Thunderstorms are rare in the cold, dry Arctic, but a surprising event in August 2019 has scientists rethinking how these storms form in polar regions. A team of researchers from the University of Science and Technology of China has uncovered new insights into this phenomenon.

Extreme weather and climate events—such as heat waves and heavy rainfall—have significant effects on ecosystems, infrastructure, and society. To monitor these extremes, scientists usually compare current conditions to a historical "climate baseline," typically a 30-year period, such as 1981 to 2010.

Researchers are combining data on earthquake shaking intensity, crowdsourced traffic data from the Waze navigation app and police crash reports to find out if car crashes are more likely during seismic events.

Beneath Yellowstone lies a magma reservoir, pulsing with molten and superheated rock and exsolved gases. Scientists have long known about the chamber's existence, but have yet to precisely locate its uppermost boundary and characterize the contents of the chamber closest to the surface—information crucial for understanding the potential perils this volcanic feature poses.

In 2021, while revelers across America celebrated the fourth of July, three researchers waded through a shallow river delta in the New Mexican desert. Abby Eckland, Irina Overeem and Brandee Carlson stood in what remained of the Rio Grande—years of drought had shrunk the river to a few small channels. Just downstream, the channels entered the Elephant Butte Reservoir—New Mexico's largest.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

Most evidence for plate motions in the geological past comes from remnant magnetization of crustal rocks. These indicate progressive changes in latitude with respect to the magnetic dipole. While such paths are often only apparent since relative motions can be explained by continental drift, there is a component of true polar wander. Since spin organizes the convecting core’s geodynamo, polar wander implies motions of the whole Earth with respect to the planet’s rotation axis.

Vaes and van Hinsbergen [2025] provide a reanalysis of paleomagnetic data and find wander rates of approximately 3 centimeters per year, consistent with a smooth response of the moments of inertia to density anomalies shifting within mantle convection. The data cannot rule out faster motions on timescales shorter than approximately 10 million years ago, and there are uncertainties such as due to the non-unique absolute motions of the entire lithosphere with respect to the deep mantle. However, the polar motion paths appear controlled by the connected system of subduction and lowermost mantle anomalies, substantiating earlier suggestions. This system also controls core heat flow, and with it perhaps the nature of the dynamo.

Moreover, some of the deep anomalies have distinct geochemical signatures as seen from plume-sourced hotspots. The geographic links of such reservoirs with the Wilson cycle arise from polar wander as well as absolute and relative plate motions, and the associated interactions remain to be fully integrated in planetary evolution models. Such work is crucial for better estimates of paleoclimate as well as an integrative view of continental geology within the core and mantle components of the Earth system.

Citation: Vaes, B., & van Hinsbergen, D. J. J. (2025). Slow true polar wander around varying equatorial axes since 320 Ma. AGU Advances, 6, e2024AV001515. https://doi.org/10.1029/2024AV001515

—Thorsten Becker, Editor, AGU Advances

Text © 2024. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Geophysical Research Letters

The use of solar power is growing rapidly, especially in developing regions in the tropics, as countries work toward meeting carbon neutrality goals. But according to new research, solar power use is also accompanied by solar power shortages, or “droughts,” when demand exceeds supply for at least 3 days. Such shortages can leave millions without access to cooling or cooking abilities.

Lei et al. analyzed global supply and demand for solar power from 1984 to 2014, looking for instances of these 3-day shortages and the conditions under which they occur. Over that time, the western United States, eastern Brazil, southeastern Asia, and much of Africa each experienced at least five solar power droughts per year, and solar power droughts increased at a rate of 0.76 additional shortage per decade. This increase in rate is responsible for 29% of the weather-driven solar droughts that occurred during the 30-year period.

Solar power droughts are driven by a combination of soaring temperatures that increase demand for cooling and inclement weather or light-blocking pollution that suppresses power generation, the researchers found. Low solar power generation typically becomes a problem during periods of high cooling demand—precisely when power is most needed to keep people comfortable and safe.

The researchers also modeled how the frequency and severity of solar power droughts could change under different emissions scenarios, assuming modern infrastructure. Under Shared Socioeconomic Pathway 2-4.5, a theoretical medium-emissions pathway used in projections by the Intergovernmental Panel on Climate Change, the researchers projected that by the 2090s, solar droughts will become 7 times more frequent and 1.3 times more severe than those in the historical period. In lower-emissions scenarios, solar power droughts peak in the 2060s and then decrease because lower emissions mean fewer heat waves.

The findings illustrate the importance of adopting mitigation measures and clean energy sources to lower emissions, the authors say. Doing so, they add, could result in a “cooler and cleaner future.” (Geophysical Research Letters, https://doi.org/10.1029/2024GL112162, 2024)

—Rebecca Dzombak, Science Writer

Citation: Dzombak, R. (2025), Solar power shortages are on the rise, Eos, 106, https://doi.org/10.1029/2025EO250145. Published on 16 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.