Dacitic Ash from the Andesitic Sheveluch Volcano, Kamchatka

Abstract

Sheveluch Volcano is one of the most productive volcanoes in Kamchatka, characterized during the Holocene by alternating periods of predominantly extrusive and explosive activity. New data on the volumetric parameters of fine ash emissions have been obtained, indicating that the mass of erupted material of dacitic composition during a single moderate-strength eruption can exceed 2 million tons. In those years when gas and ash cloud eruptions were particularly frequent (sometimes more than twenty per month), the total mass of fine dacitic ash can be comparable to the annual discharge of andesitic material (extrusive lavas and tephra), providing a new perspective on the genesis of andesites.