Reconstruction of the 29th December 2013 eruption of San Miguel volcano, El Salvador, using video, photographs, and pyroclastic deposits

Abstract

San Miguel (or Chaparrastique) volcano, El Salvador, erupted on the 29th December 2013, after almost 40 years of quiescence. Initial vent-clearing explosions ejected ballistic blocks and produced a pyroclastic density current (PDC) that flowed down the upper flanks. Plume ascent speeds peaked at 50–70 m s−1 and declined over time. The main phase of the volcanic explosivity index (VEI) 2 eruption produced a sub-Plinian plume that dispersed 106 m3 ash >20,000 km2 across El Salvador in to Honduras. Plume structure was complex due to strong wind shear and to contributions from co-PDC ash. Tephra fall deposits dispersed westwards include a basal white ash layer of ash-coated clasts and ash aggregates, a grey fine ash co-PDC layer, and a layer of coarse ash to fine lapilli-grade scoria. The eruption provides a useful case study to understand the range of volcanic activity at the volcano.