Phys.org November 21, 2022
Researchers in Japan repeatedly measured isotopic compositions of noble gases and CO2 in volcanic gases sampled at six fumaroles around the Kusatsu-Shirane volcano (Japan) between 2014 and 2021 to detect variations reflecting recent volcanic activity. The synchronous increases in 3He/4He at some fumaroles suggested an increase in magmatic gas supply since 2018. The increase in magmatic gas supply was also supported by the temporal variations in 3He/CO2 ratios and carbon isotopic ratios of CO2. The 3He/40Ar* ratios showed significant increases in the period of high 3He/4He ratios. The temporal variation in 3He/40Ar* ratios may reflect changes in magma vesicularity. Therefore, the 3He/40Ar* ratio of fumarolic gases was a useful parameter to monitor the current state of degassing magma, which was essential for understanding the deep process of volcanic unrest and may have contributed to identifying precursors of a future eruption. According to the researchers their results provide additional validation for the use of noble gas and carbon isotopic compositions of fumarolic gases for monitoring magmatic–hydrothermal systems…read more. Open Access TECHNICAL ARTICLEÂ
Ar three-isotope diagrams for the fumarolic gas samples… Credit: Scientific Reports volume 12, Article number: 17967 (2022)Â