A "giant caldera eruption" is an eruption that ejects a large amount of magma (40 cubic kilometers or more) at once to form a large-scale caldera.It has occurred 12 times in the past 10 years in the Japanese archipelago.The probability of occurrence in the next 100 years is about 1%.Huge caldera volcanoes are concentrated in Kyushu and Hokkaido, and if they erupt, great damage is expected.There is an urgent need to elucidate the mechanism of occurrence and predict eruptions.

　The Kobe University Marine Bottom Exploration Center (KOBEC) has conducted three exploration voyages at the "Kikai Undersea Caldera" in the south of Kyushu by the "Fukae Maru" training ship attached to the Graduate School of Maritime Sciences, Kobe University.Precise seafloor topography surveys, reflection seismological surveys, observations by underwater robots, rock sample collection and analysis, and observations using seafloor seismometers and potentiometers were conducted.

　As a result, it was confirmed that the largest lava dome on the earth (more than 7300 cubic kilometers) was formed in a short time after the eruption of the giant caldera 32 years ago.This lava, unlike the magma that caused the giant caldera eruption, exhibits the same chemical properties as the post-caldera volcanoes such as the current Satsuma Iojima.As a result, it is possible that a large magma chamber still exists in the Kikai Caldera.

　The research results were published in the online scientific journal "Scientific Reports" in February 2018. In May 2, it was ranked 2019th in the "Journal Top 5" published by the magazine.

reference:[Scientific Reports] Journal Top 100