Report on Kasuga 1 (United States) — January 1977
Natural Science Event Bulletin, vol. 2, no. 1 (January 1977)
Managing Editor: David Squires.
Kasuga 1 (United States) Possible submarine eruption in November 1975
Please cite this report as:
Global Volcanism Program, 1977. Report on Kasuga 1 (United States) (Squires, D., ed.). Natural Science Event Bulletin, 2:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197701-284134.
21.765°N, 143.71°E; summit elev. -598 m
All times are local (unless otherwise noted)
[A table of possible submarine eruptions based on aerial observations of water discoloration by the Japanese Maritime Safety Agency included an entry for 21.78°N, 143.71°E, in November 1975. This location is very close to Kasuga.]
Geologic Background. The Kasuga 1 seamount is a conical volcano that rises to within 598 m of the sea surface SE of Fukujin submarine volcano. It was listed as an active volcano by the Japan Meteorological Agency, and floating pumice attributed to a submarine eruption was seen south of the volcano in the summer of 1959. Water discoloration from a possible submarine eruption was reported near the seamount in November 1975. Kasuga, the northernmost of three seamounts in the the Kasuga seamount chain, rises from a depth of 3000 m. A series of flank vents are located low on the southern side of the edifice. The summit does not have a caldera or display hydrothermal activity, and the volcano is largely mantled by volcaniclastics. Altered basaltic and andesitic rocks dredged from the summit suggest that it is the oldest of the three seamounts, although delicately preserved lava flow lobes and toes from a flank eruption suggest a very youthful age.
Information Contacts: AFP; U.S. Defense Mapping Agency.