1993 年 47 巻 5 号 p. 377-390
K-Ar ages of 21 Quaternary basaltic rocks from the Kannabe Volcano Group and adjacent monogenetic volcanoes in the east San-in district were determined. In the Kannabe Volcano Group, the oldest ages, 0.7Ma, were gotten from the Nishiki Volcano. There was a long rest (about 0.5 Ma) of the volcanic activity after the eruption of the Nishiki Volcano. After that, from 0.22 Ma to recent, 6 volcanoes, if including adjacent volcanoes, 9 volcanoes, erupted intermittently. The east San-in district is the most active district of the basaltic volcanism in the San-in and Chugoku area, southwest Japan, in the present day.