Volcanic Ash Analyses Could Improve Eruption Forecasting

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A plume of smoke emerges from a volcano in the distance past hills covered in volcanic ash and trees. A field of volcanic ash during the eruption of the Cumbre Vieja volcano in the Canary Islands, located off Africa’s northwest coast. 
© Samantha Tramontano

A new study on the eruption of the Cumbre Vieja volcano in Spain’s Canary Islands suggests that on-the-ground volcanic ash studies could be used as a near-real-time monitoring and forecasting tool. 

The research, led by scientists from the Museum and the City University of New York (CUNY), offers exciting new insights into how magma composition affects volcanic activity.

Cumbre Vieja, located on the island of La Palma off Africa’s northwest coast, had been dormant for 50 years when it started erupting in the fall of 2021, causing the evacuation of thousands of people and widespread destruction. Samantha Tramontano, a Kathryn W. Davis Postdoctoral Fellow at the Museum and a faculty member in the Master of Arts in Teaching program, was a student at CUNY at the time and had the rare chance to implement a system to collect the volcanic ash produced by the eruption along with her advisor, CUNY’s Marc-Antoine Longpré. 

For three months in 2021, a team from the Museum, CUNY, and Spanish geologic agencies collected falling ash in buckets and carefully labeled the daily samples for future chemical analysis. The samples were sent back to the Museum for study with an electron microprobe, which measured the makeup of the molten material upon eruption.

Samantha Tramontano, wearing a helmet and a mask, kneels beside a hole and measures accumulated volcanic ash with a tape measure.
Study co-author Samantha Tramontano measures the accumulation of ash at the Cumbre Vieja volcano three weeks after the eruption began in 2021. 
© Samantha Tramontano

The research team, which published their work in the journal Nature Geoscience last week, is the first to capture daily changes in melt chemistry at an active volcano. One key finding: the melt chemistry changes over the course of an eruption, with a sharp change in silica content two weeks before the end of the eruption. Magma with higher levels of silica is often more viscous—thicker—and is typically associated with more explosive eruptions. 

This change in composition positively correlates with the amplitude of volcanic tremor, the seismic “rattling” that often occurs during eruptions—suggesting that magma with higher silica content could cause stronger seismic activity. 

The research highlights the value of combining chemical data from ash samples with geophysical measurements, like volcanic tremor, to improve eruption monitoring and decision-making during crises.

“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,” Tramontano said.