Growth of the lava dome and extrusion rates at Soufriere Hills Volcano, Montserrat, West Indies: 2005-2008

The third episode of lava dome growth at Soufriere Hills Volcano began 1 August 2005 and ended 20 April 2007. Volumes of the dome and talus produced were measured using a photo-based method with a calibrated camera for increased accuracy. The total dense rock equivalent (DRE) volume of extruded andesite magma (306 +/- 51 Mm(3)) was similar within error to that produced in the earlier episodes but the average extrusion rate was 5.6 +/- 0.9 m(3)s(-1) (DRE), higher than the previous episodes. Extrusion rates varied in a pulsatory manner from < 0.5 m3s-1 to similar to 20 m(3)s(-1). On 18 May 2006, the lava dome had reached a volume of 85 Mm3 DRE and it was removed in its entirety during a massive dome collapse on 20 May 2006. Extrusion began again almost immediately and built a dome of 170 Mm(3) DRE with a summit height 1047 m above sea level by 4 April 2007. There were few moderate-sized dome collapses (1-10 Mm(3)) during this extrusive episode in contrast to the first episode of dome growth in 1995-8 when they were numerous. The first and third episodes of dome growth showed a similar pattern of low (< 0.5 m(3)s(-1)) but increasing magma flux during the early stages, with steady high flux after extrusion of similar to 25 Mm(3). Citation: Ryan, G. A., S. C. Loughlin, M. R. James, L. D. Jones, E. S. Calder, T. Christopher, M. H. Strutt, and G. Wadge (2010), Growth of the lava dome and extrusion rates at Soufriere Hills Volcano, Montserrat, West Indies: 2005-2008, Geophys. Res. Lett., 37, L00E08, doi: 10.1029/2009GL041477.