Explosive Submarine Eruptions: The Role of Condensable Gas Jets in Underwater Eruptions

Abstract

AbstractIn explosive submarine eruptions, volcanic jets transport fragmented tephra and exsolved gases from the conduit into the water column. Upon eruption the volcanic jet mixes with seawater and rapidly cools. This mixing and associated heat transfer ultimately determines whether steam present in the jet will completely condense or rise to breach the sea surface and become a subaerial hazard. We develop a multiphase model with subgrid calculations for in situ steam condensation to explore the relationship between eruption conditions (e.g., water depth, mass eruption rate, and eruption temperature) and the produced steam jet height and breach potential. We find that mass eruption rate is the predominant control of jet height, more so than vent width. We present a series of parameter maps predicting the limits of eruption breach for water depths of 200, 500, and 1,000 m. We demonstrate the relationship between subsurface jets and sea surface temperature anomalies, and sea surface displacement. Lastly, we evaluate the role of dispersed ash on volcanic jet development by comparing jets with particles of different size and density, as well as differing eruption conditions with particles.