A highly explosive volcanic eruption with dense clouds of gas and tephra propelled upwards for many kilometres. Fissure eruptions are common, as are the destruction of the crater walls, and the fragmentation of solidified lavas. ‘The magma mass discharge rate governs the eruption magnitude of plinian eruptions, and depends strongly on conduit geometry’ (Varekamp (1993) J. Volc. & Geothermal Res. 54, 3–4). Arce et al. (2003) Geol. Soc. Amer. Bull. 115, 2, 230 describe the Plinian eruption of Nevado de Toluca volcano, Mexico.