Eruption history of Akanfuji in the Me-akan volcano, eastern Hokkaido, has been examined by comparing multiple natural outcrops. In a previous study, at least 17 layers of scoria fall deposits were recognized. To obtain more detailed geological information and reexamine the eruptive activity of Akanfuji, we conducted trench surveys. At each survey site, the scoria fall deposits from Akanfuji are layered with a total thickness of several tens of centimeters to 1 m. A light brown volcanic ash layer is deposited just under the lowest layer of Akanfuji, and the fresh glass in the light brown volcanic ash shows the glass composition of the volcanic ash that erupted at Tarumai volcano 2500 BP. In addition, volcanic ash ejected from Ponmachineshiri of the Me-akan volcano is deposited on top of the newest deposits in the Akanfuji series with a thin soil layer in between. The volcanic ash ejected from Ponmachineshiri contains patches of volcanic ash from the Mashu volcano that erupted 1000 years ago. Therefore, Akanfuji was active from about 2500 to 1000 years ago. Akanfuji ejected scoria fall deposits at least 17 times (Akf-1 to Akf-17), and assuming that it erupted an average number of times during the activity period, it would be once every 90 years. The eruption rate was estimated to be 0.12 km³ DRE/ka.

1. [1] G. Wadge, “Steady state volcanism: Evidence from eruption histories of polygenetic volcanoes,” J. Geophys. Res. Solid Earth, Vol.87, No.B5, pp. 4035-4049, 1982.
2. [2] L. Civetta, Y. Cornette, P. Y. Gillot, and G. Orsi, “The eruptive history of Pantelleria (Sicily channel) in the last 50 ka,” Bull. Volcanol., Vol.50, No.1, pp. 47-57, 1988.
3. [3] K. Fontijn, F. Costa, I. Sutawidjaja, C. G. Newhall, and J. S. Herrin, “A 5000-year record of multiple highly explosive mafic eruptions from Gunung Agung (Bali, Indonesia): Implications for eruption frequency and volcanic hazards,” Bull. Volcanol., Vol.77, No.7, Article No.59, doi: 10.1007/s00445-015-0943-x, 2015.
4. [4] D. Miura, R. Furukawa, and K. Arai, “Late Pleistocene-Holocene volcaniclastic ejecta along the southern apron of the Esan volcanic complex, Japan,” J. Disaster Res., Vol.14, No.5, pp. 755-765, 2019.
5. [5] M. Yasui, M. Takahashi, T. Kanamaru, and M. Nagai, “High-resolution reconstruction of the history of large-scale eruptions of Asama-Maekake volcano based on the stratigraphy of pyroclastic fall deposits,” Bull. Volcanol. Soc. Japan, Vol.66, No.4, pp. 293-325, 2021 (in Japanese with English Abstract).
6. [6] K. Wada, “Mixing and evolution of magmas at Me-Akan volcano, eastern Hokkaido, Japan,” Bull. Volcanol. Soc. Japan, Vol.36, No.1, pp. 61-78, 1991 (in Japanese with English Abstract).
7. [7] Y. Katsui, “Geology of the Akan-Kutcharo volcanoes in Hokkaido,” Earth Science (Chikyu Kagaku), Vol.1958, No.39, pp. 19-29, 1958 (in Japanese).
8. [8] I. Yokoyama, Y. Katsui, S. Ehara, and K. Koide, “Meakandake, its volcanic geology, history of eruption, present state of activity and prevention of disasters,” Committee for Prevention of Disasters of Hokkaido, Vol.5, pp. 1-138, 1976 (in Japanese).
9. [9] K. Wada, E. Sato, and Y. Ishizuka, “Report for the drilling core sample from Me-akan volcano,” Progress reports on the description of the drilling cores sampled from JAM’s borehole type volcanic monitoring stations, pp. 12-16, 2017.
10. [10] Y. Minami, M. Nakagawa, E. Sato, K. Wada, and Y. Ishizuka, “Eruptive history during the last 1,000 years at Ponmachineshiri in Meakandake volcano, eastern Hokkaido, Japan,” Bull. Volcanol. Soc. Japan, Vol.66, No.3, pp. 211-227, doi: 10.18940/kazan.66.3_211, 2021 (in Japanese with English abstract).
11. [11] K. Wada, “Mixing mechanism of heterogeneous magmas at the somma-building stage of Meakan volcano, eastern Hokkaido, Japan,” Bull. Volcanol. Soc. Japan, Vol.34, No.2, pp. 89-104, 1989 (in Japanese with English Abstract).
12. [12] K. Wada, “Fractal structure of heterogeneous ejecta from the Me-akan volcano, eastern Hokkaido, Japan: Implications for mixing mechanism in a volcanic conduit,” J. Volcanol. Geotherm. Res., Vol.66, Nos.1-4, pp. 69-79, 1995.
13. [13] K. Wada, H. Ikegami, and T. Inaba, “Chemical compositions of the rocks from Me-akan volcano, eastern Hokkaido, Japan: Compositional variety of eruptive magmas,” Rep. Taisetsuzan Inst. Sci., No.32, pp. 43-60, 1998 (in Japanese with English abstract).
14. [14] K. Wada, “Petrology of Akanfuji basalts from Me-akan volcano, eastern Hokkaido: Two-stage mixing of tholeiitic magmas,” Rep. Taisetsuzan Inst. Sci., No.24, pp. 15-30, 1989 (in Japanese with English abstract).
15. [15] E. Sato and K. Wada, “Eruption history of Akanfuji in the Me-akan volcano, eastern Hokkaido, Japan,” Chikyu Monthly/Special, Vol.68, pp. 10-18, 2017 (in Japanese).
16. [16] T. Kuritani, E. Sato, K. Wada, A. Matsumoto, M. Nakagawa, D. Zhao, K. Shimizu, and T. Ushikubo, “Conditions of magma generation at the Me-akan volcano, northern Japan,” J. Volcanol. Geothrm. Res., Vol.417, Article No.107323, doi: 10.1016/j.jvolgeores.2021.107323, 2021.
17. [17] H. Aoyama and H. Oshima, “Tilt change recorded by broadband seismometer prior to small phreatic explosion of Meakan-dake volcano, Hokkaido, Japan,” Geophys. Res. Lett., Vol.35, No.6, Article No.L06307, doi: 10.1029/2007GL032988, 2008.
18. [18] E. Sato, K. Wada, Y. Minami, Y. Ishizuka, and M. Nakagawa, “Reinvestigation of the eruptive history of Me-akan volcano, eastern Hokkaido, during the last 14000 years using trench survey,” Programme and Abstracts the Volcanology Society of Japan, 2020, O2-D2, p. 26, 2020 (in Japanese).
19. [19] P. J. Reimer, W. E. N. Austin, E. Bard, A. Bayliss, P. G. Blackwell, C. B. Ramsey, M. Butzin, H. Cheng, R. L. Edwards, M. Friedrich, P. M. Grootes, T. P. Guilderson, I. Hajdas, T. J. Heaton, A. G. Hogg, K. A. Hughen, B. Kromer, S. W. Manning, R. Muscheler, J. G. Palmer, C. Pearson, J. van der Plicht, R. W. Reimer, D. A. Richards, E. M. Scott, J. R. Southon, C. S. M. Turney, L. Wacker, F. Adolphi, U. Büntgen, M. Capano, S. M. Fahrni, U. Büntgen, M. Capano, S. M. Fahrni, A. Fogtmann-Schulz, R. Friedrich, P. Köhler, S. Kudsk, F. Miyake, J. Olsen, F. Reining, M. Sakamoto, A. Sookdeo, and S. Talamo, “The IntCal20 Northern Hemisphere radiocarbon age calibration curve (0–55 cal kBP),” Radiocarbon, Vol.62, No.4, pp. 725-757, doi: 10.1017/RDC.2020.41, 2020.
20. [20] C. B. Ramsey, “Bayesian analysis of radiocarbon dates,” Radiocarbon, Vol.51, No.1, pp. 337-360, 2009.
21. [21] K. Wada, M. Nakamura, and M. Okuno, “Identification of source volcano from the chemical compositions of glasses from the widespread ashes in the surface layers of Asahidake volcano, central Hokkaido, Japan,” Rep. Taisetsuzan Inst. Sci. No.35, pp. 9-18, 2001 (in Japanese with English abstract).
22. [22] T. Hasegawa, M. Nakagawa, and I. Miyagi, “Re-evaluation of the history of phreatic eruptions from Atosanupuri volcano, eastern Hokkaido, Japan: Inferred from ¹⁴C ages and borehole cores of Japan Meteorological Agency,” J. Geol. Soc. Japan, Vol.123, No.5, pp. 269-281, 2017 (in Japanese).
23. [23] R. Furukawa, M. Nakagawa, C. Furukata, and M. Yoshimoto, “Pre-historic activities of Tarumai volcano, Hokkaido, north Japan,” Chikyu Monthly, Vol.28, No.5, pp. 302-307, 2006 (in Japanese).
24. [24] Y. Hayakawa, “Pyroclastic geology of Towada Volcano,” Bull. Earthq. Res. Inst., Univ. Tokyo, Vol.60, pp. 507-592, 1985.
25. [25] Y. Ishizuka, M. Nakagawa, and S. Fujiwara, “Geological map of Tokachidake volcano,” Geological Map of Volcanoes 16, Geological Survey of Japan, AIST, 2010.