Destruction of a lava dome observed with photogrammetry, acoustic and seismic sensors at Volcán de Colima, Mexico

During the period December 2016 to March 2017 the lava dome emplaced in September–November 2016 at Volcán de Colima was partially destroyed by Vulcanian explosions. In particular, 10 moderate-large explosions were observed with heights of 2–6.8 km from the crater and with the generation of pyroclastic density currents (PDCs), shock waves and ballistics. The acoustic and seismic energies were calculated for each event. The values found are similar to other moderate-large Vulcanian explosions observed at other volcanoes, the maximum value of seismic energy was of 1.6 × 109 J and for acoustic energy 7.5 × 108 J. These values were compared with the height of the eruptive column, which resulted in a poor correlation. For the acoustic signals, the reduced pressure was greater than that commonly reported for Vulcanian explosions elsewhere. Using the time or arrival of the acoustic and seismic signals, the depth of the acoustic-seismic source was estimated at <310 m for nine explosions. With photogrammetry (SfM method), the volume lost during the excavation of a crater between 5 December and 12 March was estimated, the volume being 9.8 × 105 m3. The total seismic energy released during these dates was 5.7 × 109 J. With these data, a relation between the lost volume and the total seismic energy of 1.6 × 10−4 m3/J was obtained. With this relation, the volume destroyed due to future explosions could be estimated, if the seismic energy release is known.