Eruptive flux drives atmospheric lightning rates and submarine hydroacoustic signals during the 2021 Fukutoku-Oka-no-Ba eruption

Abstract

The August 2021 eruption of Fukutoku-Oka-no-Ba (FOB) volcano in Japan was a remarkable VEI 4 shallow submarine eruption, partly because it generated a 16-km water-rich atmospheric plume, new islands, and a large pumice raft. Recent studies provide complementary summaries of the atmospheric and oceanic surface expressions of the 2021 FOB eruption, including analyses of regional infrasound and Himawari-8 geostationary satellite data. The hydroacoustic record has also been published. Following these studies, we examine how the processes occurring beneath the sea surface correlate with the intensity of the atmospheric portion of the 2021 FOB eruption. We compare multiple data sets, specifically International Monitoring System hydroacoustic and infrasonic array data in the context of ground-based lightning observations, and plume height and width data (Himawari-8). We estimate a time-varying volumetric flow rate from plume observations and compare the resulting time series with acoustic and lightning characteristics. The infrasound data do not correlate with the other data streams due to signal loss from diurnal winds. The lightning, hydroacoustic, and volume-flux data are highly correlated, and we suggest this is because all three depend on eruption flux and intensity at the vent.