Geologic Background:
Located 90 km SE of Minami-Iwo-Jima,
Minami-Hiyoshi lies near the SE end of a coalescing chain
of youthful seamounts, and is the only historically
active vent. The morphologically youthful seamounts
Kita-Hiyoshi and Naka-Hiyoshi lie to the NW, and
Ko-Hiyoshi to the SE.
Historic Activity:
- Periodic water discoloration and water-spouting has
been reported over this submarine volcano since 1975,
when detonations and an explosion were also
reported.
Recent Activity:
- Overflights reported discolored water several times
during February and March 1992, for the first time since
the late 1970's.
- On Jan. 12, 1996, discolored seawater was observed
over a 500 m wide and 6 km long area, flowing from
Minami-Hiyoshi seamount to the south.
Data Sources:
- Global Volcanism Network (V. 17, No. 2 and V. 21, No.
1).
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