Long-term eruptive trends from space-based thermal and SO2 emissions: a comparative analysis of Stromboli, Batu Tara and Tinakula volcanoes

摘要

Batu Tara (Indonesia) and Tinakula (Solomon Island) are two poorly known volcanoes with morphologies and short-term eruptive activity similar to Stromboli (Italy). However, quantitative information about their long-term eruptive behaviour is limited, making the comparisons with Stromboli descriptive and based on short periods of observations. Here, we use over a decade of satellite data to measure and compare the radiant flux (2000-2017) and the SO2 mass (2004-2017) of all three volcanoes. The combined analysis of volcanic radiant power (from MODIS data) and SO2 flux (from OMI data) reveals different long-term eruptive trends and contrasting ratios of SO2/VRP. These data indicate that the eruptive mechanisms operating at each volcano are quite different. The persistent open-vent activity of Stromboli volcano is episodically interrupted by flank eruptions that drain degassed magma stored in the very shallow portion of the central conduit. In contrast, a long-lasting exponential decay of both VRP and SO2 flux observed at Batu Tara is consistent with the eruption of undegassed magma from a deep, closed magma chamber, whilst Tinakula displays multiple year-long eruptive phases, characterised by evolving gas/thermal ratios and an eruptive intensity increasing with time. Magma budget calculations for the latter volcano are consistent with eruption from a volatile-zoned magma chamber, coupled with periods of gas/magma accumulations at depth. Our results suggest that the combined analysis of satellite thermal/gas data provides a valuable tool for decrypting the long-term volcanic dynamics that could remain hidden over shorter timescales.