Field and seismic evaluation of the block-and-ash flows emplaced from eruption columns of the 2005 Vulcanian explosions at Volcan de Colima, Mexico

摘要

The May-September 2005 Vulcanian explosion sequence was the most intense of all the activity during the recent 1998-2015 unrest at Volcan de Colima, Mexico. This study presents field measurements of volume and runout distances of block-and-ash flows emplaced from eruption columns that punctuated the six largest explosions of this sequence. The energy of these explosions and the emplacement duration of the pyroclastic flows were obtained from broad-band seismic signals associated with these events. The field and seismic characteristics of the 2005 explosions at Volcan de Colima and associated block-and-ash flows showed that six explosions with energy ranging between 3.0 x 10(11) and 1.5 x 10(13) J emplaced the block-and-ash flows with volumes ranging between 1.8 x 10(5) and 3.1 x 10(5) m(3) DRE (dense rock equivalent). Analysis of durations of seismic signals associated with the movement of the 2005 block-and-ash flows emplaced from the eruption columns allowed us to quantify them as M3-magnitude events using the techniques proposed by Zobin et al. (Bull Volcanol 67: 679-688, 2005) to quantify the block-and-ash flows emplaced from the partial collapse of the lava dome at Volcan de Colima.