Thermal-image-derived dynamics of vertical ash plumes at Santiaguito volcano,Guatemala

Vertical ash plumes were imaged at Santiaguito (Guatemala) using a thermal camera to capture plume ascent dynamics. The plumes comprised a convecting plume front fed by a steady feeder plume. Of the 25 plumes imaged, 24 had a gas thrust region within which ascent velocities were 15–50 m s⁻¹. A transition to buoyant ascent occurred 20 to 50 m above the vent, where ascent velocities declined to 4–15 m s⁻¹. Plumes that attained greater heights had higher heat contents, wider feeder plumes and higher buoyant ascent velocities.