Volcanologists discover how bubbles accumulate in magma

Eth Zurich

Tambora on the Indonesian island of Sumbawa: the explosive eruption of this volcano 200 years ago cooled the climate and lead to a year without a summer. Together with other scientists from ETH Zurich and Georgia Institute of Technology (Georgia Tech), the researchers studied the behaviour of bubbles with a computer model. In many volcanic systems, the magma reservoir consists mainly of two zones: an upper layer consisting of viscous melt with almost no crystals, and a lower layer rich in crystals, but still containing pore space. Parmigiani explains this as follows: when the proportion of bubbles in the pore space of the crystal-rich layers increases, small individual bubbles coalesce into finger-like channels, displacing the existing highly viscous melt. Through this mechanism, a large number of gas bubbles can accumulate in the crystal-poor melt under the roof of the magma reservoir.

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