Explosive volcanic eruptions triggered by cosmic rays; Volcano as a bubble chamber

Ebisuzaki, Toshikazu*; Miyahara, Hiroko*; Kataoka, Ryuho*; Sato, Tatsuhiko   ; Ishimine, Yasuhiro*

We examined the timing of 11 eruptive events that produced silica-rich magma from four volcanoes in Japan (Mt. Fuji, Mt. Usu, Myojin-sho, and Satsuma-Iwo-jima) over the past 306 years (from AD 1700 to AD 2005). Nine of the 11 events occurred during inactive phases of solar magnetic activity (solar minimum), which is well indexed by the group sunspot number. This strong association between eruption timing and the solar minimum is statistically significant to a confidence level of 96.7%. This relationship is not observed for eruptions from volcanoes with relatively silica-poor magma, such as Izu-Ohshima.