When reports of volcanic eruptions spewing lava and ash emerge, concerns for nearby populations naturally arise. Astonishingly, almost one in ten people worldwide reside within 100 kilometers of an active volcano. Understanding the drivers behind these eruptions is crucial for those living, farming, or visiting areas in close proximity to these geological wonders.

A groundbreaking research study, published today in Science Advances, introduces the application of laser technology to analyze the chemical composition of erupted magma over time. As magma’s chemistry directly impacts its fluidity, explosivity, and hazardous potential, this innovative work can significantly contribute to future monitoring and forecasting of volcanic eruption evolution.

Magma, the molten rock, consists of liquid (“melt”), gases, and crystals that form as the magma cools during its ascent to the Earth’s surface. Once the magma erupts and becomes lava, it releases gases such as water vapor, carbon dioxide, and sulfur dioxide, transforming into volcanic rock. This rock, characterized by crystals formed slowly within the volcano and a finer matrix rapidly cooled at the surface, often bears a resemblance to “rocky road” chocolate.

To gain insights into the run-up to an eruption, researchers focused on the melt that transports the crystals to the surface. They employed an ultraviolet laser, akin to those used in eye surgery, to target the rock matrix between larger crystals. Subsequently, mass spectrometry was used to analyze the laser-generated particles and determine the chemical composition of the volcanic matrix. This method allows for swift chemical analysis, providing a more detailed understanding of melt chemistry evolution over time compared to traditional rock analysis or laborious separation of matrix and crystal fragments from crushed rock samples.

The study centered on the 2021 eruption at La Palma, the most destructive volcanic event recorded historically in the Canary Islands. Throughout September to December 2021, over 160 million cubic meters of lava engulfed more than 12 square kilometers of land. The eruption resulted in the destruction of 1,600 homes, forced the evacuation of more than 7,000 people, and incurred losses exceeding €860 million (AU$1.4 billion). Lava samples collected systematically by collaborators in Spain during the three months of the eruption proved invaluable for the research, as the precise eruption day was known, and many sampling sites are now covered by later lavas from the event.

Utilizing the laser-powered technique, the researchers discerned variations in lava chemistry associated with seismic changes, sulfur dioxide emissions, eruption styles, and resulting hazards. These observations included a transition from thick lavas with bulldozer-like qualities at the eruption’s onset to more fluid lavas that created rapid lava rivers and tunnels as the event progressed. Furthermore, a crucial shift in lava chemistry approximately two weeks before the eruption’s conclusion suggested magma cooling due to a reduction in magma supply, providing potential insights for monitoring future eruptions.

While we cannot prevent volcanoes from erupting, advancements in volcano monitoring have significantly improved over recent decades, allowing scientists to indirectly glean valuable information about these enigmatic phenomena. The current study aims to provide a laboratory tool for examining volcanic samples collected during future eruptions, with the ultimate goal of unraveling the intricacies of eruption evolution to understand their initiation and cessation.

With approximately 50 volcanoes erupting worldwide at any given time, these findings underscore the importance of volcano science in enhancing our understanding of how these geological wonders operate and what triggers their eruptions. By fortifying our knowledge, we can better protect the communities residing near these volcanic hotspots.

By Impact Lab