Deep-sea evidence for distribution of tephra from the mixed magma eruption of the Soufrière on St. Vincent, 1902: Ash turbidites and air fall

The 7 May 1902 eruption of the Soufrière on St. Vincent in the Lesser Antilles island arc was a mixed magma eruption that produced both andesitic (65%) and dacitic magma (35%) of narrow compositional range. Evidence from land and deep-sea coring indicates that the eruption produced three types of mixed deposits that have been correlated by means of electron microprobe analyses of glass shards: air-fall ash in the Tobago Trough east of St. Vincent, pyroclastic flow deposits on flanks of the volcano, and an ash turbidite in the Grenada Trough west of St. Vincent, which formed during pyroclastic flow discharge into the sea off the west coast of the volcano and subsequent slumping of the coastline. The main dispersal axis and fallout pattern of ash as deduced from contemporary ships' logs and coring data, indicate that air-fall distribution was controlled by antitrade winds, with transport velocities of approximately 60 km/hr.