On the dynamical behaviour of low-frequency earthquake swarms prior to a dome collapse of Soufriere Hill volcano, Montserrat

A series of low-frequency earthquake swarms prior to a dome collapse on Soufriere Hills volcano, Montserrat, are investigated with the emphasis on event rate and amplitude behaviour. In a single swarm, the amplitudes of consecutive events tend to increase with time, while the rate of event occurrence accelerates initially and then decelerates toward the end of the swarm. However, when consecutive swarms are considered, the average event rates seem to follow the material failure law, and the time of the dome collapse can be successfully estimated using the inverse event rate. These patterns in amplitude and event rate are interpreted as fluctuations in magma ascent velocity, which result in both the generation of low-frequency events as well as cyclic ground deformation accompanying the swarm activity. Citation: Hammer, C., and J. W. Neuberg (2009), On the dynamical behaviour of low-frequency earthquake swarms prior to a dome collapse of Soufriere Hill volcano, Montserrat, Geophys. Res. Lett., 36, L06305, doi: 10.1029/2008GL036837.