Volatile Messengers: Unraveling the Secrets of Magma Chambers through Volcanic Gas Analysis

Yves Moussallam (intro: Marielle Collombet) - Columbia University

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Volcanic eruptions pose significant threats to communities and infrastructure worldwide. To effectively mitigate these risks, it is crucial to identify early warning signs and anticipate volcanic activity. One promising approach involves monitoring the chemistry of volcanic gases, which can provide valuable insights into the hidden processes within magma chambers. However, deciphering the complex language of gas geochemistry has been a formidable challenge.

In this seminar, I will provide an introduction to the fascinating field of volcanic gas geochemistry. I will review the various techniques used to measure gas emissions at active volcanoes and address some of the controversies surrounding their interpretations.

Following this overview, I will present an innovative method for interpreting volcanic gas compositions, enabling us to track variations in the temperature and oxidation state of the source magma over time. To demonstrate the accuracy and potential of this approach, I will compare these findings with independent estimates obtained from the study of melt inclusions.

Applying this method to a comprehensive global database of high-temperature volcanic gases, I will re-analyze extended gas geochemical time series from Unzen, Aso, and Asama volcanoes. The new approach reveals previously undetected but significant changes in magma properties that preceded or coincided with shifts in volcanic activity. I will argue that critical processes such as magma chamber recharge events or second boiling can be deciphered from gas geochemistry, which, when analyzed in detail, could thus be used for improving our ability to forecast eruptions.