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Exploring Textural Signatures of Submarine Volcanism in Rafted Pumice from the 2019 Eruption of Volcano F, Tonga

Sarah Ward1, Kristen Fauria2, Martin Jutzeler3, Jhardel Dascent4, Vashan Wright4, Nadia McGlynn1

  • Affiliations: 1Vanderbilt University, 2National Energy and Technology Laboratory, 3University of Tasmania, 4University of San Diego Scripps Institute of Oceanography

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 219

  • Programme No: 3.6.23

  • Theme 3 > Session 6

Abstract

Submarine eruptions can produce swaths of floating pumice (pumice rafts). These rafts, measuring tens to thousands square kilometers, can be a hazard for marine and coastal infrastructure. They can also preserve volcanic deposits which might otherwise be difficult to access on the seafloor. As such, rafts provide an opportunity to quantify the bubble textures of submarine pumice, which can elucidate bubble nucleation and growth dynamics at submarine eruptions. In August 2019, "Volcano F," a submarine volcano located along Tonga-Kermadec Arc, produced a 195 km2 pumice raft that was sampled at sea near the vent (50-200 km) and distally (900 km). We quantify the connectivity (c) and total porosity (φ) of 45 pumice lapilli by helium pycnometry. Results reveal abundant isolated porosity in high total porosity pumice (φ > 65%, c < 0.6 ). Based on a literature review of 2300 pairs of total porosity-connectivity measurements in volcanic pumice, we deem this texture rare at sub-aerial eruptions but common at submarine eruptions. To explore the texture further, we analyze X-Ray Computed Tomography images of 7 breadcrusted pumice, with abundant isolated pores, from rim to core. We find that clast total porosity increases from rim to core and that isolated pores are more abundant in clast rims, which is consistent with rapid quenching of an outer rim due to interaction with external water. Abundant isolated pores are also present in clasts without breadcrust textures. Thus, more work is needed to understand limits on bubble nucleation, growth, and coalescence in submarine settings.