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Temporal variations of helium isotopes in volcanic gases quantify pre-eruptive refill and pressurization in magma reservoirs; the Mount Etna case

Antonio Paonita, Antonio Caracausi, Mauro Martelli and Andrea L. Rizzo
Temporal variations of helium isotopes in volcanic gases quantify pre-eruptive refill and pressurization in magma reservoirs; the Mount Etna case
Geology (Boulder) (July 2016) 44 (7): 499-502

Abstract

Two approaches to the challenging aim of forecasting impending eruptions are searching for empirical precursors and developing suitable interpretative models. Here we present high-resolution time series of (super 3) He/ (super 4) He ratios measured in gases emitted from peripheral vents around Mount Etna volcano (Italy), which revealed variations with strong correlations over both time and a broad spatial scale. The main eruptive episodes are preceded by increases in (super 3) He/ (super 4) He, making this ratio a unique tracer for monitoring volcanic activity. These features strongly reflect pressurization beneath the volcano due to deep magma influx. We propose a pioneering model that relates the changes in (super 3) He/ (super 4) He to the time-dependent outflow of volatiles from a magmatic chamber subjected to evolution of its internal pressure due to magma injection. At Mount Etna, the model makes it possible to estimate in near real time key parameters such as the rate of magma input and volume change in deep chamber preceding eruptions, and to compare them with geodetic estimations. This represents an unprecedented use of (super 3) He/ (super 4) He to obtain quantitative information on the physics of magmatic systems. Volcanoes showing changes of (super 3) He/ (super 4) He ratio in discharged gases due to unrest episodes are widespread in the world, and therefore we envisage extensive future applications of this approach.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 44
Serial Issue: 7
Title: Temporal variations of helium isotopes in volcanic gases quantify pre-eruptive refill and pressurization in magma reservoirs; the Mount Etna case
Affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Palermo, Italy
Pages: 499-502
Published: 201607
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 22
Accession Number: 2016-070832
Categories: Quaternary geologyEnvironmental geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016166; includes appendices
Illustration Description: illus. incl. 1 table
N37°45'00" - N37°45'00", E15°01'00" - E15°01'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201634
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