资源环境科技发展态势分析平台

Dome collapse is a dramatic volcanic process, yet the dynamics and evolution of dome collapse still present open questions. Observational data are rare, and this limits our ability to interpret the evolution of this phenomenon in terms of risk assessment. We show how the partial dome collapse of Soufriere Hills Volcano on 2010 evolved in less than 45min and was characterized by five main different episode of dome failure process. Time and amplitude of seismic and infrasonic records associated with successive pyroclastic density currents show a nearly quadratic temporal trend suggesting a self-accelerating process increasing in intensity up to the failure limit. Each episode generated gravity waves in the atmosphere, representing the first evidence of internal waves formed due to propagation of density currents in stratified fluids. Finally, we use gravity waves to estimate the total erupted mass and the plume height of the Vulcanian explosions triggered by the decompression induced by the collapse.

Plain Language Summary Dome collapse is a dramatic and highly dangerous volcanic process involving the destabilization of large volume of hot material rushing as turbulent and destructive flows for kilometers down the flanks of the volcano. Dome collapse may trigger also large volcanic explosions that injecting a large amount of ash into the atmosphere constitute a serious risk for the air traffic. Dynamics of the dome instability still present open questions limiting our ability to assess the related hazard. Recent dome collapse reveals a strong interaction with the atmosphere. We show that collapse dynamics is able to induce buoyancy oscillations of the whole atmosphere generating gravity waves. These waves as linked to density currents were only theoretical predicted, and this is the first evidence in natural environment. We show that the collapse evolved in five main steps lasting only 45min and that forecast methods based on seismoacoustic wavefield can be used to predict the end of the collapse. Finally, we used the oscillation of the atmosphere to estimate the mass of ash injected and the plume height of the Vulcanian eruption triggered by the collapse.