Simultaneous creation of a large vapor plume and pumice raft by a
shallow submarine eruption
Abstract
The August 12, 2021 eruption of Fukutoku-Okanoba, a shallow submarine
volcano in the Izu-Bonin arc of Japan, is one of few documented
submarine eruptions to make a large aerial plume and floating pumice
raft. Relative to past eruptions, this event was well-covered by
multiple high resolution satellite remote sensors. Here we use satellite
remote sensing to assess the eruption style, rates, and products. We
find that the 16 km plume was water-rich. Furthermore, we conclude that
the 0.1 km^3 raft and 16 km plume were co-genetic and suggest that
pumice clasts were delivered to the raft by tephra jets rather than
plume fallout. Finally, this eruption highlights a discrepancy between
small erupted volumes and high plume heights that may be common for
shallow explosive subaqueous eruptions.