The previous eruption history of Fuji volcano has been re-examined by new 100 radiometric carbon ages. The major unconformity between Ko-Fuji and Shin-Fuji volcanoes of Tsuya (1968, 1971) was caused by the edifice collapse resulting in the Tanukiko debris avalanche at about Cal BC 18,000. Voluminous effusion of basalt lava flows in the older ejecta of Shin-Fuji volcano (Tsuya, 1968, 1971) had started at about Cal BC 15,000 and continued until about Cal BC 6,000. Deposition of black soil layer between the Older and Younger Fuji tephra layers of Machida (1964, 1977) started at Cal BC 8,000. After several thousands years quiescent time, basaltic eruptions in the middle ejecta of Shin-Fuji volcano (Tsuya, 1968, 1971) had restarted at about Cal BC 3,600 and thin lava flows had piled up as the central volcanic cone, until about Cal BC 1,700. The eruption style of the volcano changed into explosive basaltic eruptions from the summit and the flank at about Cal BC 1,500; the S-10 to S-22 scoria fall deposits were generated in this first half period of the younger ejecta of Shin-Fuji volcano (Tsuya, 1968, 1971). Also, basaltic pyroclastic flows cascaded down the western flank at about Cal BC 1,500, Cal BC 1,300, Cal BC 1,000 and Cal BC 770. The last summit explosive eruption (S-22) occurred at about Cal BC 300. Immediately after the S-22 eruption, basaltic fissure eruptions had repeated at the flanks until the 1707 Hoei eruption. New data suggest that the Fudosawa, Nissawa and Suyama-tainai lava flows in the southern flank are historical products at about Cal AD 1,000.
- Key words:
- Fuji volcano, radiometric carbon age, eruption history