GEOLOGIC HISTORY
Akan is a 13x24 km elongated caldera that formed more
than 31,500 years ago. Its caldera lake is restricted by
four post-caldera stratovolcanoes. Of the four post-caldera
Holocene stratovolcanoes, only the Me-Akan group have been
historically active. Located near the SW end of the Kurile
arc, Akan is the southernmost of three adjacent calderas in
the NE part of Hokkaido.
Historic Activity: Eruptions in 1927, 1951, 1952,
1954 to 1960, 1962, and from 1964 to 1966.
Recent Activity:
- Minor eruptive activity occurred at Meakandake Cone,
within the caldera, on January 5, 1988. Associated
volcanic earthquakes and weak volcanic tremor also
occurred. Additional eruptions occurred on the nights of
Feb. 7-8 and 18-19. Continuous steam emission since
February eruptions.
- Sharp increase in volcanic seismicity in September
& October 1989 and January & February 1990.
Another increase in June through October 1990.
- Increased seismicity from late September thru
November 1992, but declined in December. Another increase
in seismicity occurred during April 1993. Continued
seismicity in May. Another increase in seismicity in
August 1995. Also seismicity in Oct. and Nov.
- Increase in seismicity in August 1996 beneath
Me-Akan. Seismicity remained high from Aug. to Nov. Small
phreatic explosion occurred on Nov. 21, no juvenile
material. Seismicity in December but no volcanic
tremor.
Data Sources
- Smithsonian's SEAN Bulletin (V. 7, No. 3 to V. 13,
No. 10)
- Global Volcanism Network (V. 15, No. 5 to V. 23, No.
10).
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