Types and mechanisms of strombolian explosions: characterization of a gas-dominated explosion at Stromboli

摘要: Textural and chemical analyses of bombs quenched directly from a normal explosion at Stromboli volcano (Italy) were integrated with coincident seismic, acoustic, thermal data. The data set defines new gas-dominated type “strombolian” eruption, named 0. These events are characterized by high-velocity emission (150–250 m s−1) few relatively small, juvenile particles, entrained non-juvenile clasts that previously fell back into the vent to be re-erupted. For studied event, depth was more than 250 deep, particles showed little residence time in shallow system. Slug ascent velocities over final 20–35 magma-filled conduit, low viscosity resident magma, all consistent simple bubble burst “clean” conduit. This conduit eruption style likely fit popular slug models used explain eruptions. In contrast, ballistic-dominated explosions (type 1) associated larger proportions stagnant material system magma mix. We argue additional volume this pushes free surface upward. Because available for entrainment 1 burst, which has fragment through thick cap degassed material, tend rich particles. less spectacular, gas-rich 0) have entrain, thus being poor lapilli bombs.