Scientists from UC San Diego’s Scripps Institution of Oceanography have detected geochemical signatures of magma pooling and melting beneath the subsurface during the “Fagradalsfjall Fires,” that began on Iceland’s Reykjanes peninsula in 2021.

Continuous sampling of the erupted lavas from the Fagradalsfjall volcano enabled a detailed time-series analysis of geochemical signals. These show that the start of the eruption began with massive pooling of magma, contrasting the initial hypothesis for magma ascent straight from the mantle.

Scripps Oceanography geologist James Day and his colleagues report on the analyses July 31 in the journal Nature.

“By collecting lavas at regular intervals, and then measuring their compositions in the laboratory, we can tell what’s feeding the volcano at depth,” said study lead Day. “It’s a bit like taking regular measurements of someone’s blood. In this case, the volcano’s ‘blood’ is the molten lavas that emanate so spectacularly from it.”

Day, students at Scripps Oceanography, and international colleagues have been studying basaltic lavas from other recent volcanic eruptions in addition to Iceland. These include the 2021 eruption of the Tajogaite volcano on the island of La Palma in the Canary Islands and the 2022 eruption of Mauna Loa in Hawai’i. They have found evidence for similar magma pooling beneath La Palma.

“What makes the Iceland eruption so remarkable is the huge signal of crust within the earliest lavas,” said Day. “Along with our studies from La Palma, it suggests crustal magma storage may be a common process involved in the run up to larger basaltic eruptions like those in Iceland or the Canary Islands. This information will be important for understanding volcanic hazard in the future,” he added, “as it may help to forecast volcanic activity.”

Previous studies had suggested that the Fagradalsfjall Fires erupted from the surface without interaction with the crust. Day’s team, including UC San Diego undergraduate student Savannah Kelly, used the isotopic composition of the element osmium to understand what was happening beneath the volcano.

“What’s useful about using osmium,” said Day, “is that one of its isotopes is produced by the radiogenic decay of another metal, rhenium. Because the elements behave differently during melting, one of the elements, rhenium, is enriched in Earth’s crust.” Day and colleagues took advantage of the distinct behaviors of rhenium and osmium to show that the early lavas from the Fagradalsfjall Fires were contaminated by crust.

Earth can be broken up into a series of layers. The deepest portion is the metallic core. The shallowest layers are the atmosphere, ocean, and the rocky crust. All human beings live on the crust, which is dominated by rock types such as granite or basalt like that found in Iceland’s lavas. In between the core and crust is the vast mantle of the Earth. This mantle layer is where melting occurs to produce the magmas feeding volcanoes like those in Iceland.

Previous work published on the recent volcanic eruptions on the Reykjanes Ridge had used other geochemical fingerprints to study the lavas. These fingerprints suggested only mantle contributions to the lavas. Osmium isotopes are highly sensitive to the crust and enabled the unambiguous identification of its addition into the early lavas.

“The work began as undergraduate research experience for Savannah (Kelly) and we fully expected to see mantle signatures in the lavas throughout the eruption,” said Day. “You can imagine our astonishment when we were sitting in front of the mass spectrometer measuring the early samples and saw obvious signals of crust within them.”

The team analyzed lavas erupting from the Fagradalsfjall volcano in 2021 and in 2022. The 2021 lavas were contaminated by crust, the 2022 lavas were not. They conclude that the earliest lavas pooled in the crust and interaction with the crust may have helped trigger the eruption.

“After that, it appears that the magma of later eruptions used pre-existing pathways to get to the surface,” Day said.

Day and colleagues plan to continue their work on Iceland and other basaltic eruptions into the future. Previous eruptions on the Reykjanes peninsula have lasted for centuries.

“It seems that the volcanic ‘fires’ in Iceland will outlast me,” Day said. “The eruptions that are likely to continue there will provide a treasure trove of important scientific information on how volcanoes work and their associated hazards. Our study shows that the beginning of the eruption was not just visually spectacular, but was also geochemically so.”

Besides Day and Kelly, Geoffrey Cook of Scripps Oceanography, William Moreland and Thor Thordarsson from the University of Iceland, and Valentin Troll from Uppsala University in Sweden were involved in the research.

A new paper from Carnegie Mellon University indicates that giving students more autonomy leads to better attendance and improved performance. The research was published in the journal Science Advances.

In one experiment, students were given the choice to make their own attendance mandatory. Contradicting common faculty beliefs, 90% of students in the initial study chose to do so, committing themselves to attending class reliably or to having their final grades docked. Under this “optional-mandatory attendance” policy, students came to class more reliably than students whose attendance had been mandated.

Student choice in learning

The pattern has held true. In additional studies across five classes that included 60–200 students, 73%–95% opted for mandatory attendance, and at most 10% regretted their decision by the semester’s end.

“Like Ulysses, students know they will face significant temptations. By making their attendance mandatory, they exercise self-control over their future behavior,” said first author Simon Cullen, assistant professor in the Department of Philosophy and Dietrich College AI and Education Fellow.

“We are born curious, and we naturally enjoy mastering many challenging learning tasks, but controlling course policies like mandatory attendance can undermine that motivation.”

The role of autonomy in academic success

According to Cullen, the findings challenge widely held beliefs about student behavior. He continues that many educators worry that given the choice, students would opt for the easiest path possible. However, this study paints a starkly different picture.

“Anytime in a class that you give freedom to choose, you give students the feeling of control over their education,” said Danny Oppenheimer, professor in the Social and Decision Sciences and Psychology departments at CMU and co-author of the article. “It puts the learning in the students’ hands and increases their motivation.”

Preparing students for real-world challenges

A second experiment indicated that when given the option to switch to an easier homework stream at any time before midterms, 85%–90% of students chose to tackle the more challenging work. The “optional-mandatory homework” policy led students to spend more time on their assignments and to learn more over the semester compared to students who were compelled to complete the same work. Cullen gauged the improved understanding of the material by examining how well students did on the problem sets throughout the semester.

These findings suggest that the common practice of imposing strict rules on college students may be counterproductive. Cullen and Oppenheimer found that allowing students more autonomy could lead to better academic outcomes and prepare them more effectively for the real world.

“The thought was that giving them greater control over their own learning would prepare them for the real world,” Cullen said. “Students can be driven to excel in our classes by the same sources of motivation that drive them to pursue countless projects and passions that require no external incentives. But only if we let them choose to learn.”

Enhancing Engagement and Retention in Higher Education

The researchers note their findings also highlight a significant gap in current educational practices. Despite decades of research demonstrating the importance of autonomy to motivation, autonomy-promoting policies remain rare in higher education.

“It’s as if we’ve been ignoring one of the most powerful tools in our educational toolkit,” said Oppenheimer. “By harnessing students’ intrinsic motivation to learn through increased autonomy, we achieve better results than through external pressure.”

The researchers caution that their findings, while promising, have limitations. The study was conducted at a single university with a limited number of students, and more research is needed to determine if the results will replicate across different types of institutions and student populations. The authors are collaborating with a diverse set of institutions to test its broader applicability.

“We’re super excited about these results, but we’re also eager to see how our interventions work across a range of settings,” Cullen said. “We’re particularly interested in exploring how autonomy might benefit students from disadvantaged backgrounds and those with disabilities.”

The study opens up new avenues for research and practical applications in higher education. The authors suggest that similar choice architectures could be applied to other aspects of college courses, such as deadlines, course materials and even exam formats.

“As colleges and universities grapple with issues of student engagement, retention and academic success, this research offers a fresh perspective,” said Cullen. “By trusting students with more control over their education, institutions might not only improve academic outcomes but also foster a more positive and empowering learning environment.”