Dynamics of giant pumice dispersal in deep sea eruptions

Abstract:

It is estimated that more than half of silicic volcanism on Earth occurs underwater, making it important to understand how water affects the explosivity of eruptions and the transport of eruptive products. One large (>1 km³) and comparatively well-studied submarine eruption, the 2012 eruption of Havre Volcano, Kermadec Arc has raised questions about the mechanisms that disperse giant (> 1 m) pumice clasts and that allow some erupted clasts to float while others sink. Here we explore results from a series of laboratory experiments that shed light on the production and fate of pumice clasts from submarine eruptions. By measuring the internal temperature and liquid water saturation rate in over thirty experiments, we develop a model for the coupled cooling and water ingestion of pumice. Our model suggests that individual giant pumice clasts can reach the ocean surface from 900 m depth in ~5 minutes, but may sink back to the seafloor within 20 minutes. Assuming dispersal by ocean currents, we test our model against the distribution of giant pumice measured within 6 km of the vent at Havre submarine volcano. We observe that the density of giant pumice increases with distance from the vent and conclude that our model does not fully capture the dynamics of giant pumice dispersal and deposition.