Explosive volcanic history and hazard zonation maps of Boqueron Volcano (San Salvador volcanic complex, El Salvador)
Explosive volcanic history and hazard zonation maps of Boqueron Volcano (San Salvador volcanic complex, El Salvador) (in Understanding open vent volcanism and related hazards, William I. Rose (editor), Jose Luis Palma (editor), Hugo Delgado Granados (editor) and Nick Varley (editor))
Special Paper - Geological Society of America (November 2013) 498: 201-230
Boqueron Volcano, formed on the old San Salvador Volcano, is the youngest and active central edifice of the San Salvador volcanic complex, which also includes 25 secondary vents. The San Salvador volcanic complex is located in the vicinity of the San Salvador metropolitan area and is considered one of the most hazardous volcanic centers in El Salvador and Central America. Boqueron Volcano has a long record of effusive and explosive eruptions spanning 36,000 yr; the most recent eruption was in 1917. We reviewed and updated its eruptive history through detailed fieldwork, allowing the recognition of up to 25 different eruptions. Lava flows, ash-fall, and ballistic projectile deposits produced by Strombolian or violent-Strombolian eruptions are the most recurrent events preserved in the stratigraphic record of Boqueron Volcano. Pyroclastic-flow, and especially pyroclastic-surge, deposits are also present, indicative of explosive subplinian and Plinian eruptions, some of which had significant phreatomagmatic components. We define three hazard scenarios regarding ash fall, ballistic projectiles, and pyroclastic density currents for Boqueron Volcano and constrain them using its documented explosive eruptive history, fieldwork, and computer simulations. Each scenario is characterized by a likelihood of occurrence (high, medium, low), assigned to eruptive events of small, intermediate, or large magnitude, which are mainly characterized for the areal distribution of the related volcanic products. Resulting hazard maps show areas likely to be affected by future eruptions, enabling decision makers and the general public to consider volcanic hazards in land development and risk mitigation planning.