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Fig. 3 | Earth, Planets and Space

Fig. 3

From: Source constraints for the 2015 phreatic eruption of Hakone volcano, Japan, based on geological analysis and resistivity structure

Fig. 3

Variation in rock chemistry of SPW52. To depict the modification of the chemical composition due to the hydrothermal alteration, all oxide contents are standardized using that of Al2O3, which is considered the most immobile element during hydrothermal alteration. The samples from deep depths (≤ 858 m asl) form a cluster, whereas those from shallower depths scatter, which indicates higher alteration at shallower depths. The deeper and shallower depths indicate no significant difference for the Fe and Ti content (a); however, lower Na, Si (b), Ca, Mg (c), and K (d) indicate leaching of those elements at shallow depths. The higher sulfur content in the shallow depths indicates that sulfuric acid is a leaching agent (d)

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