The past 3000 years' eruptive history of the Yakedake volcano, located in the southern part of the Northern Japan Alps, central Japan, has been revealed by tephrostratigraphy as well as radiocarbon dating. We identified eleven tephra layers from the Yakedake volcano. These are named Yakedake-Tougezawa tephra group (Ykd-T) and are stratigraphically divided into two sub-groups ; the lower (Ykd-Tl) and the upper (Ykd-Tu) subgroups. The tephra layers are very poorly sorted and mainly composed of altered fine-grained ash including lithic fragments. Only one tephra bed, Ykd-TNkb, is a fine-grained vitric ash. Based on stratigraphy, the Ykd-TNkb could have been supplied by the eruption of the Nakao pyroclastic flows and the Yakedake lava dome (ca. 2300 cal BP). Judging from observations on the AD 1962 historical eruptive products, there is little chance to detect a phreatic eruption smaller than 1×10
6 m
3 eruption volume in geologic records. Frequency of phreatic eruptions greater than 1×10
6 m
3 during the past 3000 years is estimated to be 2-8 times/ky. On the other hand, magmatic eruptions occurred only once during a few thousand years. This revealed that Yakedake volcano was the most active volcano in the Norikura volcanic zone during the past 10, 000 years. On the basis of calibrated radiocarbon data, stratigraphic relation and historical records, it is probable that Ykd-Tu2 tephra erupted in AD685, Ykd-Tu7 tephra in AD1746 and Ykd-Tu8 tephra in AD 1907-1939.
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