“If we don’t understand the underlying tectonic processes, it’s hard to predict the seismic hazard,” said coauthor Amanda Thomas, professor of earth and planetary sciences at UC Davis.

A Seismic Crossroads Beneath the Coast

The Mendocino Triple Junction lies offshore from Humboldt County, where three major tectonic plates converge. South of this junction, the Pacific plate moves roughly northwest alongside the North American plate, creating the San Andreas fault. To the north, the Gorda (or Juan de Fuca) plate moves northeast and sinks beneath the North American plate, descending into the Earth’s mantle in a process known as subduction.

Although this arrangement may appear simple on a map, scientists say the real structure below the surface is far more complicated. One striking example came from a large (magnitude 7.2) earthquake in 1992 that struck at a much shallower depth than expected.

Looking Below the Surface

First author David Shelly of the USGS Geologic Hazards Center in Golden, Colo., said the challenge is similar to studying an iceberg.

“You can see a bit at the surface, but you have to figure out what is the configuration underneath,” Shelly said.

To uncover that hidden structure, Shelly and his colleagues used a dense network of seismometers across the Pacific Northwest. The instruments recorded extremely small “low-frequency” earthquakes that occur where tectonic plates slowly slide against or over one another. These tiny events are thousands of times weaker than earthquakes people can feel at the surface.

The team tested their underground model by examining how these small earthquakes respond to tidal forces. Just as the gravitational pull of the Sun and Moon affects ocean tides, it also places subtle stress on tectonic plates. When those forces line up with the natural direction of plate movement, the number of small earthquakes increases, Thomas said.

Five Moving Pieces Beneath Northern California

The researchers found that the region involves five moving pieces rather than just three major plates, with two of them hidden deep below the surface.

At the southern end of the Cascadia subduction zone, the team discovered that a portion of the North American plate has broken away and is being dragged downward along with the Gorda plate as it sinks beneath North America.

South of the triple junction, the Pacific plate is pulling a mass of rock known as the Pioneer fragment beneath the North American plate as it moves northwards. The fault separating the Pioneer fragment from the North American plate lies nearly flat and cannot be seen at the surface.

The Pioneer fragment was once part of the Farallon plate, an ancient tectonic plate that once extended along the California coastline and has since mostly disappeared.

Explaining a Puzzling Earthquake

This updated model helps explain why the 1992 earthquake occurred at such a shallow depth. According to Materna, the surface being pushed beneath North America is not as deep as scientists previously believed.

“It had been assumed that faults follow the leading edge of the subducting slab, but this example deviates from that,” Materna said. “The plate boundary seems not to be where we thought it was.”

The work was supported by a grant from the National Science Foundation.

The returning crew included NASA astronauts Zena Cardman and Mike Fincke, JAXA (Japan Aerospace Exploration Agency) astronaut Kimiya Yui, and Roscosmos cosmonaut Oleg Platonov. Their SpaceX Dragon capsule touched down at 12:41 a.m. PST, after which recovery teams aboard SpaceX vessels quickly secured the spacecraft and assisted the astronauts.

Science Success and International Collaboration

“I couldn’t be prouder of our astronauts and the teams on the ground at NASA, SpaceX, and across our international partnerships,” said NASA Administrator Jared Isaacman. “Their professionalism and focus kept the mission on track, even with an adjusted timeline. Crew-11 completed more than 140 science experiments that advance human exploration. Missions like Crew-11 demonstrate the capability inherent in America’s space program — our ability to bring astronauts home as needed, launch new crews quickly, and continue pushing forward on human spaceflight as we prepare for our historic Artemis II mission, from low Earth orbit to the Moon and ultimately Mars.”

Over the course of the mission, the crew devoted hundreds of hours to scientific research, station maintenance, and testing new technologies. They also marked a historic milestone on Nov. 2, 2025, celebrating 25 years of uninterrupted human presence aboard the orbiting laboratory. Research conducted on the space station continues to expand scientific understanding while supporting future missions beyond Earth orbit.

Early Return Due to Medical Concern

Crew-11 returned to Earth about one month earlier than planned after teams identified a medical concern involving one crew member. NASA confirmed the individual remains stable but did not release further details to protect medical privacy.

Ahead of the return, NASA arranged for all four astronauts to be transported to a local hospital following splashdown. This allowed the crew to receive additional medical evaluation using Earth-based resources. After a planned overnight stay, the astronauts will travel to NASA’s Johnson Space Center in Houston, where they will begin standard postflight evaluations and physical reconditioning.

Mission Timeline and Time in Orbit

The Crew-11 mission began on Aug.1, 2025, with a launch at 11:43 a.m. EDT from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Approximately 15 hours later, the SpaceX Dragon spacecraft docked with the International Space Station at 1:27 a.m. CDT on Aug. 2.

During their 167 days in space, the crew completed more than 2,670 orbits of Earth and traveled nearly 71 million miles. The mission marked the fourth spaceflight for Mike Fincke and the second for Kimiya Yui, while Zena Cardman and Oleg Platonov flew their first missions. Fincke has now accumulated 549 total days in space, placing him fourth among NASA astronauts for cumulative time spent in orbit.

Commercial Crew Program and Future Missions

NASA’s Commercial Crew Program continues to provide consistent access to space by partnering with private U.S. companies, including SpaceX. These collaborations allow astronauts to travel to and from the International Space Station while maximizing the station’s role as a hub for research and technology development.

The successful return of Crew-11 highlights the program’s ability to support complex missions, respond to unexpected challenges, and keep human spaceflight moving forward as NASA prepares for future exploration of the Moon and Mars.

Scientists led by the University of Leeds launched the largest and longest experiment ever designed to examine how nutrients shape forest regrowth. The work focused on tropical areas previously cleared for activities such as logging and agriculture.

Tracking Forest Regrowth Over Decades

The researchers selected 76 forest plots across Central America and monitored them for as long as 20 years. Each site differed in age and size, allowing the team to follow how trees grew and died as forests recovered over time.

To test the role of nutrients, the plots received different treatments. Some were given nitrogen fertilizer, others phosphorus fertilizer, some received both nutrients, and some were left untreated. This approach allowed the scientists to directly compare how forests responded under different soil conditions.

Nitrogen Emerges as a Key Driver

The results showed that soil nutrients strongly influence how quickly tropical forests regrow. During the first 10 years of recovery, forests with adequate nitrogen rebounded at about twice the rate of those lacking it. Phosphorus alone did not produce the same effect.

The study included researchers from the University of Glasgow, the Smithsonian Tropical Research Institute, Yale University, Princeton University, Cornell University, the National University of Singapore, and the Cary Institute of Ecosystem Studies. The findings were published on January 13 in the journal Nature Communications.

Implications for Climate and Reforestation

Lead author Wenguang Tang, who carried out the research while completing his PHD at the University of Leeds, said: “Our study is exciting because it suggests there are ways we can boost the capture and storage of greenhouse gases through reforestation by managing the nutrients available to trees.”

Although nitrogen fertilizer was used in the experiment, the researchers do not recommend fertilizing forests. Widespread fertilizer use could lead to harmful side effects, including emissions of nitrous oxide, a powerful greenhouse gas.

Instead, the team suggests practical alternatives. Forest managers could plant trees from the legume (bean) family, which naturally add nitrogen to the soil. Another option is restoring forests in areas that already have sufficient nitrogen due to the effects of air pollution.

Why Faster Regrowth Matters for the Climate

Tropical forests are among the world’s most important carbon sinks. They help slow climate change by removing carbon from the atmosphere and storing it in trees, a process known as carbon sequestration.

The researchers estimate that if nitrogen shortages affect young tropical forests worldwide, about 0.69 billion tonnes of carbon dioxide may be failing to be stored each year. That amount is roughly equal to two years of carbon dioxide and other greenhouse gas emissions in the U.K.

Policy Relevance After COP 30

The study is released just weeks after the close of COP 30 in Brazil, where the Tropical Forest Forever Facility (TFFF) fund was announced. The initiative aims to help tropical forest countries protect existing forests and restore those that have been damaged.

Principal investigator Dr. Sarah Batterman, an Associate Professor in Leeds’ School of Geography, said: “Our experimental findings have implications for how we understand and manage tropical forests for natural climate solutions.

“Avoiding deforestation of mature tropical forests should always be prioritized, but our findings about nutrient impacts on carbon sequestration is important as policymakers evaluate where and how to restore forests to maximize carbon sequestration.”

The research, recently published in Nature, introduces a redesigned OLED that combines a flexible phosphorescent polymer layer with transparent electrodes made from MXene nanomaterial. This approach allows the display to stretch up to 1.6 times its original length while retaining most of its brightness.

“This study addresses a longstanding challenge in flexible OLED technology, namely, the durability of its luminescence after repeated mechanical flexion,” said Yury Gogotsi, PhD, Distinguished University and Bach professor in Drexel’s College of Engineering. “While the advances creating flexible light-emitting diodes have been substantial, progress has leveled off in the last decade due to limitations introduced by the transparent conductor layer, limiting their stretchability.”

Why OLEDs Lose Performance When Bent

OLEDs generate light through a process known as electroluminescence. When electricity flows through the device, positive and negative charges move between electrodes and pass through an organic polymer layer. When these charges meet, they release light and form a particle called an exciton before settling into a stable electrical state. Adjusting the chemical composition of the organic layer determines the color of the emitted light.

Flexible OLEDs are made by depositing these layers onto bendable plastic substrates, allowing them to function while folded, bent, or rolled. The technology was first developed in the 1990s and became widely visible in the 2010s when Samsung incorporated flexible displays into shatter-resistant devices and curved-edge phones. Over time, however, it became clear that repeated bending caused OLED brightness and flexibility to decline due to gradual damage in the electrodes and organic materials.

“Imparting conducting materials with flexibility usually involves incorporating an insulating but stretchable polymer that hinders charge transport and, as a result, reduces light emission,” said Danzhen Zhang, PhD, a co-author and postdoctoral researcher at Northeastern University, who conducted early work on transparent conductive MXene films as a PhD student in Gogotsi’s lab at Drexel. “In addition, the material most commonly used in electrodes can become brittle and more likely to break the longer the OLED is flexed and stretched. This issue was addressed by using MXene-contact stretchable electrodes, which feature high mechanical robustness and tunable work function, ensuring efficient hole or electron injection.”

A New Light-Emitting Layer

To overcome these challenges, the researchers redesigned the light-emitting portion of the OLED. Their solution uses a specialized organic layer that increases how often electrical charges combine to form excitons, leading to stronger light output.

This material, called an exciplex-assisted phosphorescent (ExciPh) layer, is naturally stretchable and engineered to adjust the energy levels of moving charges. By making it easier for charges to meet and form excitons, the layer boosts light production, similar to slowing a spinning ride so more people can step on safely.

More than 57% of excitons created in the ExciPh layer are converted into light. In comparison, the polymer-based emissive layers commonly used in today’s OLEDs achieve only a 12-22% conversation efficiency rate.

To further improve flexibility, the team incorporated a thermoplastic polyurethane elastomer matrix into the ExciPh layer. They also focused on improving how electrical charges move through the device by redesigning the electrodes.

MXene Electrodes Boost Durability and Brightness

The new electrodes combine MXene, a highly conductive two-dimensional nanomaterial developed by Drexel researchers in 2011, with silver nanowires. Together, these materials form a conductive network that helps electrical charges reach the light-emitting polymer layer more efficiently before forming excitons.

This structure improves charge injection and allows the OLED to maintain its brightness even while being bent and stretched.

“Owing to their exceptional conductivity and layered form, MXenes provide an exceptional electrode material for flexible OLEDs,” Gogotsi said. “We have demonstrated the performance of flexible, transparent MXene electrodes in multiple applications; thus, including them in efforts to improve OLED technology is a natural step for our research.”

Testing OLEDs Under Repeated Strain

Using these combined improvements, the researchers produced flexible green OLED displays, including one shaped like a heart and another showing numerical digits. They measured the charge-to-exciton conversion rate — a measure of the OLEDs’ ability to efficiently produce light — along with performance during repeated stretching.

To demonstrate broader potential, researchers at Seoul National University also built a full-color, fully stretchable OLED display using four dopant materials within the ExciPh layer. In addition, they created fully stretchable passive-matrix OLEDs that showcase a simple, low-power design suitable for wearable electronics.

Compared with previous designs, the new OLEDs showed higher brightness and better energy efficiency. When stretched to 60% of their maximum strain, performance dropped by only 10.6%. After 100 cycles of repeated stretching at 2% strain, the displays retained 83% of their light output, indicating significantly improved durability.

Toward Wearable and Deformable Displays

“We anticipate the success of this approach to designing flexible, high-efficiency optoelectronic devices will enable the next generation of wearable and deformable displays,” said Teng Zhang, PhD, a co-author and former post-doctoral researcher in Gogotsi’s lab. “This technology will play an important role in real-time health care monitoring and wearable communications technology.

Future work may involve testing alternative flexible substrates, fine-tuning organic layers to produce different colors and brightness levels, and simplifying the manufacturing process to support large-scale production of stretchable OLED devices.