A new study reveals that magma composition could drive volcanic tremors, potentially transforming how eruptions are monitored and forecasted. Researchers collected and analyzed ash samples from the Cumbre Vieja volcano, finding significant insights that could aid in future hazard assessments.
New research led by scientists from the American Museum of Natural History and the City University of New York (CUNY) has revealed a significant link between magma composition and volcanic tremors. Based on detailed sampling and analysis of ash from the 2021 eruption of the Cumbre Vieja volcano, the research offers new possibilities for monitoring and forecasting volcanic activity.
The eruption of Cumbre Vieja on La Palma, in Spain’s Canary Islands, in September 2021 came after 50 years of dormancy. This volcanic event devastated the island, prompting the evacuation of thousands of residents and destroying over 3,000 buildings and extensive farmland over 85 days.
Amid this chaos, a team led by Samantha Tramontano, a Kathryn W. Davis Postdoctoral Fellow at the Museum, and her then-advisor Marc-Antoine Longpré, an associate professor of volcanology and igneous petrology at CUNY’s Queens College, launched an ambitious project to collect near-daily ash samples.
“The volcano research community has gotten much better in recent years at forecasting the start of a volcanic eruption, but it’s still hard to predict eruption style and duration,” Tramontano said in a news release. “If our findings hold true for other volcanoes, we might be able to monitor interior magma properties from the surface of an eruption, and that could be very important for hazard assessment.”
This impressive effort, in collaboration with the Instituto Volcanológico de Canarias and the Instituto Geográfico Nacional, allowed the team to capture 94% of the eruption timeline. Back at the Museum, these samples underwent chemical analysis using an electron microprobe, leading to a daily time series of the liquid magma composition — an unprecedented dataset.
Among the key findings was a variation in silica content within the magma. Since higher silica concentrations make magma more viscous, such magma is typically linked to more explosive eruptions. Observations showed an increase in silica content during the eruption’s initial week, a gradual decline and a sudden increase two weeks before the eruption concluded, indicating a possible end to the mantle magma supply.
A correlation emerged between the silica levels and the strength of volcanic tremors — seismic activity caused by fluid movements beneath the volcano’s surface. The researchers suggest that high-silica magma amplifies volcanic tremors, though further studies are needed to fully understand this mechanism.
“A big challenge for petrological monitoring is the coordination of fieldwork and sample transfer during eruption crises to enable fast analysis,” added Longpré. “Careful pre-planning and technological developments should make efficient, near-site sample analysis possible in the future, better supporting timely interpretation of geophysical data.”
The study, published in Nature Geoscience, underscores the potential of integrating petrological data, such as ashfall composition, with geophysical analyses to enhance eruption forecasting and hazard assessment. This integrative approach could significantly improve decision-making during volcanic crises.