昭和新山噴気孔ガス凝縮水中の化学成分の連続観測

概要

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The aim of this research is focused on the following two points: 1) To examine whether the constancy of the chemical composition of fumarolic gas is established or not in a short period (10-20 hrs.). 2) To examine the feasibility of chemical forecast of volcanic eruption by knowing the chemical behavior of fumarolic gases in calm periods of a volcano. Sampling of condensed water and measurement of temperature and relative flow rate were made 24 times at the intervals of 1 hr. at a fumarole of Volcano Showa-shinzan on 17th. August, 1958. Chemical components analysed are pH, Cl^-, F^-, NO_3^-, SO_4^-, B, Na^+, K^+, Mg^<++>, and Ca^<++>. The results obtained are: 1) Little time variation of the temperature of fumarolic gas is observed (653±2℃). 2) About ±5% fluctuations are found for the concentration of Cl^-, F^-, and B in the "normal" samples. The Cl:F:B ratio is almost constant in these samples, viz., Cl:F:B = 37:9.3:1 (wt. ratio). 3) "Abnormal" samples are classified into the following three types, (1) KCl contamination (2) KNO_3 contamination (3) dilution with water vapor. (1) and (2) are due to the abrupt feeds of KCl and KNO_3 to the fumarolic gas separatedly. Almost all of the abnormal samples are followed by the increase of SO_4^<--> and the decrease of F^-. We cannot explain the ultimate cause of the occurrence of abnormal samples.
特定非営利活動法人日本火山学会の論文
1959-02-20