マグマの情報をもたらすSO₂ 放出量—火山ガス測定技術の現在とその課題—

抄録

Volcanic gases are high temperature gases degassed from a magma at depths, emitting to the surface. The volcanic gases give us important clues for understanding of eruptive phenomena as their emissions are closely related to the amount of degassed magma within the volcano. The quantification of the volcanic gases is also important for environmental problems and disaster preventions because they contain toxic species. The main components of the volcanic gases are water, carbon dioxide, and sulfur dioxide (SO₂). The SO₂ gas has been used as an index of volcanic gas flux because SO₂ is readily quantified using remote-sensing techniques based on ultraviolet (UV) spectroscopy and the atmospheric air is SO₂ free. In this article, the importance of the SO₂ flux and overview of current and future remote-sensing approaches from ground are discoursed. Benefits for practical operations given from the recent developments are highlighted, stressing how these brand-new techniques could be applied to help monitoring of volcanoes.