Preservation of Isolated Vesicles in Submarine Pumice and Implications for Submarine Slope Stability

Pumice clasts from submarine eruptions contain abundant isolated vesicles that are completely encased in glass. As erupted clasts cool, gas inside isolated vesicles contracts, leading to low pressures inside those vesicles. Despite low pressures, isolated vesicles can be preserved in submarine pumice deposits to water depths of approximately 1–2 km because the compressive strength of glass exceeds the stresses created by the pressure difference between the inside of gas‐filled vesicles and the ambient pressure. If pumice rafts require abundant isolated vesicles, vents at greater depths are unlikely to form pumice rafts. Fracturing the glass enclosing isolated vesicles during shearing or slope failure would release low pressure vapor, lowering pore pressure and increasing effective stress in the sediment. Pumice‐rich deposits may thus strengthen during shear, making them more gravitationally and seismically stable than other submarine sediments.