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Earth, Planets and Space
Fig. 12 | Earth, Planets and Space

Fig. 12

From: Variation of volcanic gas composition during the eruptive period in 2014–2015 at Nakadake crater, Aso volcano, Japan

Fig. 12

Schematic diagrams showing the mechanism of the composition variation observed during the eruptive period. a On 12 January 2015, gases discharge during intensive ash eruptions are derived from a wide range of pressure from 20 to 0.2 MPa, causing a rapid and large variation in gas composition, in particular of CO2/SO2 and SO2/H2S ratios. The fumarolic gases likely be derived from gases separated at a high pressure. b On 17 March, the rapid and large variation of gas composition indicates bubble ascent from a wide range of pressure. But decrease in the composition range suggests decrease in the maximum degassing pressure and decrease in contribution of bubbles formed at a high pressure. c On May 2015, the stable gas composition implies degassing of a well-mixed magma under a stable condition

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