Geology · 1987 · 274 citations · 0 references
Natural SciencesEarth SciencesGeophysicsMineralogyPetrologyVolcanologyMagma GenesisVolcanic AshVolcanic DepositsVolcanic EruptionsVolcanic PetrologyVolcanic RocksAsh Fall DepositsAsh Particle Size DistributionAsh Plume DispersionBubble-wall InteractionsDeposit Dispersal PatternsVolcanic Ash DispersalVolcanic Ash FallVolcanic Eruption Dynamics
One of Earth's largest known eruptions, the Toba eruption of 75 ka, erupted a minimum of 2800 km 3 of magma, of which at least 800 km 3 was deposited as ash fall. This ash may be entirely of coignimbrite origin and dispersed widely because of high drag coefficients on the predominantly bubble-wall shards. Shards of this shape are broken from the walls of spherical vesicles, which formed in high abundance in isotropic strain shadows near phenocrysts in this crystal-rich magma. © 1987 Geological Society of America.