Decade-long study of degassing at Kudriavy volcano, Iturup, Kurile Islands (1990–1999): Gas temperature and composition variations, and occurrence of 1999 phreatic eruption

• Published in: Earth, planets, and space planets, and space, 2002-01, Vol.54 (3), p.337-347
• Main Authors: Korzhinsky, Mikhail A., Botcharnikov, Roman E., Tkachenko, Sergey I., Steinberg, Genrikh S.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Degassing; Depletion; Deuterium; Fumaroles; Gas composition; Gas temperature; Gases; High temperature; Isotope composition; Magma; Meteoric water; Temperature; Volcanic eruptions; Volcanoes
• ISSN: 1880-5981; 1880-5981
• DOI: 10.1186/BF03353032

A high-temperature (up to 940°C) fumarolic activity at Kudriavy volcano had been studied during 1990–1999. The maximum gas temperatures of the fumaroles were measured in 1992 as 940°C, then gradually decreased with time and reached to 907°C in 1999. Gas composition of the high-temperature fumarole became enriched in H2O and depleted in other gas components, in particular in CO2. Hydrogen isotopic compositions of the high-temperature fumarolic gases were gradually depleted in deuterium. The gradual and continuous decrease in temperature and changes in gas composition observed during the last 10-year suggest that a magmatic melt have been degassing in a relatively steady-state manner from a single magma chamber. The detail investigations in 1998 and 1999 revealed short-term changes in gas composition characterized by sporadic increases in H2, CO2, and Stotal after intense precipitations. Small-scale eruptions occurred on October 7, 1999 at the summit. The ratios of major gas components (C/S, C/Cl, S/Cl, C/F, S/F, and Cl/F) significantly increased just prior to the eruption. The eruption at the Kudriavy volcano in 1999 was likely a phreatic eruption as a result of the intense precipitations after unusually long dry period. Meteoric water penetrated into the hot zone of volcano edifice and rapidly boiled causing the eruption.