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Paroxysmal volcanic eruptions predicted by temporal variations in helium isotopes

Primordial helium-3 (3He) enrichment is regularly detected in volcanic fluids, but its temporal variability and link with volcanic activity are still poorly constrained.

Paroxysmal volcanic eruptions predicted by temporal variations in helium isotopes

Publication date: 03/07/2020

Press, Research

Related teams :
Volcanic Systems

Related themes : Natural Hazards

A study carried out in collaboration between the Piton de la Fournaise Volcanological Observatory (OVPF-IPGP) and the National Institute of Geophysics and Volcanology (INGV – Palermo and Naples Sections) has made it possible for the first time to correlate the chemistry of the noble gases in the Piton de la Fournaise on Réunion with the evolution of volcanic activity and the composition of magmas over the millennia, over centuries and even during the recent long-lasting eruptions (2015).

As Piton de la Fournaise is one of the most active and closely monitored volcanoes in the world, its eruptive products are sampled and analysed at each eruption. The chemical and isotopic composition of gaseous emissions (thermal springs rich inCO2) located near deep seismogenic zones is also regularly characterised.

The data obtained show a significant enrichment in 3He within the volcanic gases and fluid inclusions in the magmas that led to the most voluminous eruptions and caldera collapses. Modelling of these data suggests a correspondence with the deep signature of a primordial pole of the mantle source. A significant change in fluid composition is also detected during long-lasting eruptions whose magmatic products are chemically zoned and whose intensity of activity increases with the depth of the magmas emitted.

The results of this study highlight the effectiveness of using helium isotopes to detect early the increase in deep magma input to the surface magma system. This process can modulate the rate of magmatic extrusion and thus determine major events such as the caldera collapses observed at Piton de la Fournaise in 2007 and Kilauea in 2018.

Conceptual model of the magma supply system at Piton de la Fournaise. Model 1 represents the supply of gas-rich deep magmas that produce paroxysmal eruptions and were emitted during the caldera collapses of 1931 and 2007 (R/Rac > 13.5 in fluid inclusions and thermal spring gases). Model 2 represents the stationary equilibrium situation that produces the volcano's most frequent eruptions (as in 2005). In this case, magmatic fluids are linked to a degassed component of the Réunion mantle plume (R/Rac <12.8). Photo source: IMAZPRESS

Ref : Boudoire, G., Rizzo, A.L., Arienzo, I. Di Muro, A. Paroxysmal eruptions tracked by variations of helium isotopes: inferences from Piton de la Fournaise (La Réunion island). Sci Rep 10, 9809 (2020). DOI: 10.1038/s41598-020-66260-x

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