Reexamination of the eruptive history of scoria cones on the northwestern foot of Fuji Volcano, Japan.

Abstract

Stratigraphic relations for seven scoria cones on the northwestern foot of Fuji Volcano were re-examined based trenching surveys and outcrop observations. The Yumiizuka scoria cone was formed after the Kikai-Akahoya tephra at 5,300 BC. The Tsugaoyama scoria cone’s eruption age could not be determined due to the accumulated thickness of the Omuro scoria at 1,300 BC. The Shikanokashira and Hokusei-yumiizuka scoria cones were erupted just before the Omuro scoria. Based on the thickness, degree of vesicle, and color of the essential deposits at the Katabutayama scoria cone, Omuro scoria could be derived from not only the Omuroyama but also Katabutayama scoria cones. The detected horizon of the Kozushima-Tenjosan tephra at A.D. 838 and ¹⁴C ages suggest that the Tenjin’yama-Igatonoyama and Koriike-Hakudairyuo scoria cones were constructed during A.D. 838-864, and A.D. 410-770, respectively.