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AbstractMacroseismic intensity classifies the ground shaking at a locality by comparing the observed effects on humans and buildings with the scenarios characterising each intensity degree according to a macroseismic scale. This practice may involve uncertainty in assessing intensity degree due to several factors. These uncertainties propagate to subsequent elaborations, such as the parameters of pre-instrumental earthquakes determined from macroseismic data. In Italy, more than 60 per cent of the earthquakes in CPTI15, the Italian Parametric Earthquake Catalogue covering the period 1000–2020, rely on intensity data collected in DBMI15, the Italian Macroseismic Database. Their parameters are estimated with the ‘Boxer’ software, which determines the location and magnitude starting from their macroseismic intensity distributions. In this work, we explore the potential impact of possible inaccurate intensity assessments at a single site on macroseismic parameters (i.e. locations and magnitudes) of Italian earthquakes. We select 1108 earthquakes with at least 10 intensity data points from CPTI15 that occurred in the period 1279–2020. For each event, we simulate more than 100 sets of intensity distributions, for a total of 138.327 simulations, by varying the intensities at the sites of ± 1 with a half-degree step starting from the intensity of DBMI15. Each simulated distribution is then parameterised using the same approach adopted by CPTI15 (i.e. Boxer), and the results are compared with the macroseismic epicentre and magnitude of CPTI15. The resulting parameters from all the simulated distributions are coherent with those provided by CPTI15. Locations estimates are within 5 km from CPTI15’s for 55 per cent of the cases, and within 10 km for 83 per cent. The magnitudes of 68 per cent of simulations are within ± 0.2 units of difference from the CPTI15 magnitudes and 87 per cent within ± 0.3 units, similar to the statistical error of instrumental magnitude estimation. Moreover, we treat uncertain intensity values (i.e. 6–7) as equally representative of either the lowest intensity level (i.e. 6–7 as 6) and the highest intensity level (i.e. 6–7 as 7), and we analyse their impact on the parameters. The differences with the CPTI15 magnitude are not significant for either analysis, with more than 97.7 per cent of the earthquakes falling within ± 0.3 units of difference.

The central estimate of the remaining carbon budget for 1.5°C is 130 billion tons of carbon dioxide (CO2) (from the beginning of 2025). This would be exhausted in a little more than three years at current levels of CO2 emissions, according to the latest Indicators of Global Climate Change study published in the journal Earth System Science Data, and the budget for 1.6°C or 1.7°C could be exceeded within nine years.

An international team of geoscientists, chemists and climate scientists, has found evidence of a possible ghost plume beneath the territory of Oman. In their paper published in the journal Earth and Planetary Science Letters, the group describes the different types of evidence for the plume they found and what it could mean for the study of plate tectonics.

Submarine canyons around Antarctica tend to have less sea ice, higher sea surface temperatures, and more biomass such as phytoplankton blooms than the shelves they cut into. Phytoplankton blooms feed Antarctic krill, making these canyons an attractive feeding ground for larger predators such as penguins, who make permanent homes for foraging and breeding on the shores surrounding submarine canyons.

During the last ice age, storms soaked the now-arid Southwestern U.S., while today's rainy Pacific Northwest remained relatively dry. As global temperatures rose and ice sheets retreated, those storms shifted north—reshaping the climate patterns that define both regions today.

Boreal peatlands in Canada provide crucial ecosystem services, from flood mitigation and water purification to storing colossal amounts of carbon and providing a habitat for species such as caribou.

Over the past several decades, more than 36,000 hectares of well pads have been constructed to house oil and gas drilling platforms in these landscapes, destroying the underlying vegetation and disrupting the flow of water through the ground.

“We want to get as close to the original state as is possible and realistic.”

Once drilling operations are finished, operators are required to return pads to a state similar to that before construction. Though restoration efforts have historically focused on tree planting, reintroducing the right mosses is crucial for restoring functional peatlands. A study in Ecological Engineering outlines a new approach to reintroduce these keystone plant species, tested for the first time at the scale of a full well pad in Alberta, Canada.

“We want to get as close to the original state as is possible and realistic, given the very long time scales that peatlands develop over,” said Murdoch McKinnon, a graduate student at the University of Waterloo and lead author of the study.

The challenge is providing the right hydrological conditions for mosses to thrive.

Removing Fill

Well pads are constructed by heaping crushed mineral fill onto a section of peat to create a harder level surface.

Traditionally, researchers in the region have reintroduced moss by first completely removing the fill, which lowers the surface so that it is closer to the water table. In some cases, they would bury some of the fill under the newly exposed peat, a technique referred to as inversion.

This process has been successful in establishing the Sphagnum mosses typical of bogs, which have acidic soil that is low in nutrients. It’s been less successful in reintroducing the Bryopsida mosses characteristic of fens, the nutrient-rich wetlands that make up almost two thirds of peatlands in Canada’s Western Boreal Plain.

“I think it’s a good approach, but maybe the surface of the pad was not low enough to have flowing water, which you need in a fen.”

To reestablish a moss community that could eventually turn into a fen, the team left some of the fill on the surface, which provided the minerals that Bryopsida mosses rely on for growth. The team then roughed up the surface with an excavator to create different microsites, which promotes species diversity.

After introducing mosses from a nearby donor fen and closely monitoring the site for two growing seasons, researchers found that conditions for the reestablishment of Bryopsida mosses were best when the water table was within 6 centimeters (2 inches) of the surface. That was often the case along the edges of the pad that received water from the adjacent peatland, whereas the mosses in the interior of the pad struggled with drier conditions.

“I think it’s a good approach, but maybe the surface of the pad was not low enough to have flowing water, which you need in a fen,” said Line Rochefort, an expert in peatland restoration at Université Laval in Quebec who was not involved in the study.

“Without addressing that, it’s hard to introduce and establish peatland vegetation on mineral substrate,” said Bin Xu, a peatland ecologist at the Northern Alberta Institute of Technology (NAIT) who worked on the project. “On the flip side, when you do have good hydrobiological conditions, it’s really easy to support peat-forming vegetation, which is encouraging.”

A well pad located near the town of Slave Lake, Alberta, was still brown immediately after researchers introduced the moss, before it started to become established. Credit: University of Waterloo

An important takeaway from the study is the importance of decompacting the surface by roughing it up to allow for not only hydrological flow across the pad but also the natural vertical fluctuation of the water table, Xu said.

He and colleagues at NAIT have now applied these lessons to three additional well pads in Alberta, and industry experts have used a similar approach on around a dozen more, Xu said. “Through informing policy and sharing the learnings with industry, we can together address the need to reclaim well pads built in peatland across the province.”

—Kaja Šeruga, Science Writer

Citation: Šeruga, K. (2025), Surface conditions affect how mosses take to former well pads in Canada’s boreal fens, Eos, 106, https://doi.org/10.1029/2025EO250227. Published on 18 June 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: Journal of Geophysical Research: Oceans

Submarine canyons around Antarctica tend to have less sea ice, higher sea surface temperatures, and more biomass such as phytoplankton blooms than the shelves they cut into. Phytoplankton blooms feed Antarctic krill, making these canyons an attractive feeding ground for larger predators such as penguins, who make permanent homes for foraging and breeding on the shores surrounding submarine canyons.

Previous studies suggested that, as on a farm, the phytoplankton blooms that attract predators were locally grown, supported by the upwelling of nutrient-rich water. But newer research shows that water moves through the canyon more quickly than phytoplankton can accumulate, so it is likely that currents transport most of the surface biomass into the canyon from other parts of the ocean. Canyons therefore act more like biomass supermarkets, to which food is delivered, than like farms.

McKee et al. examined to what degree phytoplankton grow locally in Palmer Deep canyon on the western Antarctic Peninsula versus being transported in by ocean currents. To do so, they used high-frequency radar to measure ocean currents and satellite imagery taken hours to days apart to measure levels of surface chlorophyll, a proxy for phytoplankton.

The results showed that both processes were occurring. Ocean currents appeared to bring in much of the phytoplankton that flowed on the western side of the canyon, making it more like a supermarket, the researchers write. In contrast, more phytoplankton seem to be growing in place on the eastern flank, making it more like a farm.

The authors also examined how the movement of water correlated to plankton growth, by tracking chlorophyll levels in moving parcels of water. In general, they found that water parcels that saw an increase in phytoplankton levels as they moved through the canyon tended to exhibit more clockwise motion, whereas parcels that saw decreasing phytoplankton levels showed more counterclockwise rotation. (Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2024JC022101, 2025)

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Where do Antarctic submarine canyons get their marine life?, Eos, 106, https://doi.org/10.1029/2025EO250224. Published on 18 June 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.

A new tool that assesses the level of danger posed by tsunamis in real-time has been made operational on a global scale.

New research reveals the importance of winter sea ice in the year-to-year variability of the amount of atmospheric CO2 absorbed by a region of the Southern Ocean.

In a study published in Weather, researchers estimated the current chances and characteristics of extreme hot episodes in the UK, and how they have changed over the last six decades.

Derek Cronmiller of the Yukon Geological Survey has provided a stunning set of the images of the fascinating recent failure that partially blocked the Yukon River.

Following my post yesterday about the May 2025 landslide on the Yukon River, Derek Cronmiller, who is head of Surficial Geology at the Yukon Geological Survey kindly made contact to provide further information about this most interesting failure. He has also provided an amazing set of images of the landslide.

Derek noted the following about the landslide:-

“The slide is a 9 km above Lake Laberge and happed sometime between May 14th and 18th as constrained by Sentinel imagery and river user reports.“

“The slide is 950 m wide and up to 250m long from crown to toe. It blocked ~ 45% of the active channel which is no small feat on the Yukon River! The material is finely bedded glaciolacustrine silt and clay at river level (and below) grading up to massive medium to coarse sand at the top of the main scarp with variable thickness of aeolian dune cover at the surface.  Perhaps the most interesting part of the slide is that the rupture surface daylighted somewhere in the river and thrust river bottom sediments (and vegetation) several metres above the river level. There are some great spreading structures on the slide reminiscent of sensitive clay slides in Quebec. We observed seeps daylighting at the bottom of the adjacent slopes just above river level at the transition from sands to silt and clay. Slides have occurred here in the past but an order of magnitude smaller.”

And so to the images. This image shows the landslide from a drone, looking from the crown towards the river:-

The May 2025 Yukon River landslide, viewed from a drone. Image copyright the Yukon Geological Survey, used with permission.

The very beautiful morphology of this landslide is visible with rows of back-tilted trees, with upright trees in between. Note also the uplifted toe of the landslide, including river gravels.

Let’s take a look at the toe – here is the uplifted portion, located almost half way across the former channel. The scale of the uplift here is really impressive:-

The uplifted toe of the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

For those who are unfamilar with rational landslides, and who may be wondering how this is possible, I provided a sketch of this mechanism back in 2013 at the time of the Hatfield Stainforth landslide:-

Sketch of the rotational landslide mechanism of the 2013 Hatfield Stainforth landslide. The Yukon River landslide had a similar mechanism.

This rotational generates some complex structures in the landslide, including horst and graben phenomenon:-

Horst and graben structures in the toe of the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

And this image shows the uplifted river gravels in more detail:-

Uplifted river gravels in the toe of the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

Moving up into the main body of the landslide, there are some extremely impressive back-tilted blocks:-

Back-tilted blocks in the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

And also some horst and graben structures:-

Back-tilted trees in the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

Finally, there are areas of seepage as Derek noted above, which probably gives an indication of one of the drivers of this landslide:-

Seepage in the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

This is a really interesting landslide – in many ways, a textbook example of a complex rotational failure. If I was still teaching, I would use this landslide to illustrate the mechanisms of rotational landslides.

Many thanks to Derek Cronmiller and his colleagues at the Yukon Geological Survey for providing these amazing images and the detailed commentary. I hope that they will write the landslide up for publication in due course.

Return to The Landslide Blog homepage Text © 2023. 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.

AbstractHigh-precision geoid models have traditionally been static, neglecting temporal variations. However, achieving geoid accuracy within 1-2 cm and maintaining dynamic height reference frames necessitates consideration of geoid spatiotemporal variations. GRACE/GRACE-FO and surface mass loading models provide means to estimate geoid changes, but their accuracy and reliability require further validation. This study proposes a method for dynamically maintaining regional height reference frames by integrating GNSS reference stations as core nodes and incorporating time-varying geoid data. This method dynamically corrects station heights by computing normal height variations using GNSS observations and geoid changes. Experiments conducted in Beijing and Shandong derived geoid changes using GRACE/GRACE-FO and surface mass loading, validated against long-term GNSS observations and leveling surveys. Results show a strong correlation (R ≈ 0.9; NSE > 0.4) between geoid changes derived from GRACE and surface mass loading, although amplitude discrepancies of up to 4 mm existed. In 41 experimental cases, accuracy improvement was observed in over 90 per cent of instances following geoid change corrections. In Beijing, 18 out of 26 results achieved accuracy improvements exceeding 20 per cent, five of which surpassed 90 per cent. In Shandong, 11 out of 15 results improved by over 10 per cent, including five exceeding 40 per cent. These findings confirm the feasibility and effectiveness of using GRACE/GRACE-FO and surface mass loading to estimate geoid changes. The proposed method significantly improves the accuracy of dynamic height reference frame maintenance, providing valuable insights for further refinement of geoid models.

SummaryThe Cameroon Volcanic Line (CVL) and other tectonic features in Cameroon remain enigmatic, prompting ongoing debates about their detailed crustal structure, composition, and geodynamic evolution. To shed light on the structural complexities and the underlying crustal processes, we leverage the two-step ambient noise tomography (ANT) method to obtain the 3D shear wave velocity (Vs) and the P-to-S wave speed ratio (Vp/Vs) structure of the crust beneath Cameroon. We start by cross-correlating data recorded at 32 broadband stations from February 2006 to February 2007 to extract Rayleigh wave group dispersion curves on inter-station paths. First, we invert these dispersion curves to obtain group velocity maps across different periods (5-30 s) on a regular grid (0.5o x 0.5o). We then invert the group velocities on each grid node to derive Vs and Vp/Vs as a function of depth. Specifically, we leverage a new evolutionary algorithm called Competitive Particle Swarm Optimization (CPSO) to tightly constrain Vs and Vp/Vs ratios beneath the CVL and surrounding regions. Our inversion results show an anomalously low Vs of ~3.6 km/s in the uppermost crust beneath active volcanic provinces. This low Vs and a high Vp/Vs ratio suggest a mafic composition, possibly due to mafic volcano-plutonic melts driving Cenozoic to modern magmatic activity. Our findings reveal a prominent high-Vs structure at 25-35 km depth, in alignment with the CVL. Characteristic properties, such as the maximum Vs of ~3.9 km/s and Vp/Vs in the range of 1.85-1.88, suggest the presence of cooled mafic materials that have intruded the crust. Our depth cross-sections along the CVL indicate that these mafic intrusions are ubiquitous along the entire CVL. They are spatially separated from the volcano-plutonic structures by a thin middle crust with a Vs of ~3.7–3.8 km/s and a Vp/Vs of 1.70. These properties are indicative of a felsic to intermediate crust, which may be linked to the Neoproterozoic Pan-African Orogeny. We posit that this thinned low Vp/Vs structure may have facilitated the ascent of mafic material, contributing to recent volcanic activity in the region. Conversely, beneath the Oubanguides belt and the Congo craton, these low Vp/Vs structures appear thicker, with mafic intrusions at greater depths. This structural feature suggests a dynamic process involving the pushing and exhumation of lower crustal material by the mafic material. Our images further suggest that an intriguing interaction of crust with deeper structures may be responsible for the intrusions and volcanism observed along the CVL. The findings advance our understanding of the geological and geodynamic complexities associated with the CVL and its origin.

AbstractThe seismic behavior of the near-trench plate interface of the Guerrero seismic gap and other segments of the Mexican subduction zone is likely to play a critical role in the seismic and tsunami hazard of the region. In this context, a detailed study of the near-trench 18 April 2002 Mw 6.7 earthquake that occurred about 55 km off the coast of Guerrero and generated a small tsunami attains particular importance. From an analysis of the teleseismic P waves and S waves, local recordings, and aftershock distribution, we find that the rupture most likely began at a subducted seamount, propagated unilaterally towards NW, parallel to the trench for ~ 54-58 km and a duration of ~ 68-70 s. The moment rate function is highly rugged, with two dominant pulses separated by about 50 s. Although relatively small in magnitude, the earthquake has all the characteristics of a tsunami earthquake: the slip occurs very close to the trench, the rupture speed is slow (~ 1 km/s), the high-frequency radiation is deficient, and, in common with tsunami earthquakes, the moment-scaled radiated energy is low (ER/M0 = 1.45 × 10−6). We confirm that the duration of the event (~ 70 s) is extraordinarily long compared to that expected from scaling relations (~ 12.8 s), consistent with it being the most anomalous of all the events studied in the last 40 years (Duputel et al., 2013). Our results support a conditionally stable upper 15 km of the plate interface in the region reported from recent offshore seismic observations.

The cloud fraction diurnal variation (CDV) regulates the Earth system's radiative budget and balance, influencing atmospheric variables such as temperature and humidity, as well as physical processes like precipitation and tropical cyclones. However, significant simulation biases of CDV exist in climate models. To date, most model evaluations have focused on the daily mean cloud fraction (CFR), while the CDV has received less attention.

Between 50 and 1,000 kilometers above our heads is the ionosphere, a layer of Earth's upper atmosphere consisting of charged particles: ions (atoms that have gained or lost a negatively charged electron) and loose electrons. The ionosphere alters the path of electromagnetic waves that reach it, including radio and GPS signals, so studying it is helpful for understanding communication and navigation systems.

A study has found New Zealand's native forests are absorbing more carbon dioxide (CO2) than previously thought. Study leader, NIWA atmospheric scientist Dr. Beata Bukosa says the findings could have implications for New Zealand's greenhouse gas reporting, carbon credit costs, and climate and land-use policies. The research was published in Atmospheric Chemistry and Physics.

Wildfires pollute waterways and could affect their ability to sequester carbon, recent University of British Columbia research shows.

A small, multi-institutional team of climate scientists has found evidence that human-caused impacts on the stratosphere began earlier than previously thought. In their study, published in the Proceedings of the National Academy of Sciences, the group used observational data, environmental theory and computer modeling to create simulations depicting the state of the stratosphere to a time just after the dawn of the industrial age.

Source: Radio Science

Between 50 and 1,000 kilometers above our heads is the ionosphere, a layer of Earth’s upper atmosphere consisting of charged particles: ions (atoms that have gained or lost a negatively charged electron) and loose electrons. The ionosphere alters the path of electromagnetic waves that reach it, including radio and GPS signals, so studying it is helpful for understanding communication and navigation systems.

One way to study the ionosphere is to “nudge” it with powerful radio waves sent from the ground to see how it reacts. Where the waves hit the ionosphere, they temporarily heat it, changing the density of charged particles into irregular patterns that can be detected from the way they scatter radio signals. By studying these irregularities, known as artificial periodic inhomogeneities (APIs), scientists can learn more about the ionosphere’s composition and behavior.

However, factors such as space weather and solar activity can inhibit both the formation and detection of APIs. La Rosa and Hysell sought to enhance the reliability and utility of the API research technique by examining API formation in all three main regions of the ionosphere, the D, E, and F regions. Past techniques focused only on API formation in the E region.

To do so, the researchers revisited data from research conducted in April 2014 at the High-frequency Active Auroral Research Program (HAARP) facility in Alaska. HAARP’s radio transmitters created small perturbations in the ionosphere, and the facility’s receivers captured the resulting scattered radio signals.

Initial analysis of the 2014 data revealed some APIs in the E region, but this team of researchers reprocessed the data at higher resolution. This reanalysis allowed them to document, for the first time, simultaneous APIs across all three regions, all triggered by a single radio nudge.

API formation in each of the three regions is dictated by a different set of mechanisms, including chemical interactions, heating effects, and forces that change the density of charged particles; this variability has made it difficult to develop a stand-alone model of API formation across the ionosphere.

To address that challenge, the researchers extended a model previously created to capture API formation in the E region by incorporating the relevant mechanisms for the D and F regions. In simulation tests, the model successfully reproduced the behavior observed in all three regions. This model could help deepen understanding of the physics at play in the ionosphere. (Radio Science, https://doi.org/10.1029/2025RS008226, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Nudging Earth’s ionosphere helps us learn more about it, Eos, 106, https://doi.org/10.1029/2025EO250222. Published on 17 June 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.