Modelling the macroscopic behavior of Strombolian explosions at Erebus volcano

E. de Lauro , S. de Martino , M. Falanga , M. Palo

We analyze seismic signals associated with the Strombolian explosion quakes at Erebus volcano (Antarctica), examining the high-frequency (>0.5) portion of the spectrum. We consider recordings relative to two time periods during the years 2005 and 2006. Cross-correlation analysis allows us to distinguish three classes of events. Spectral properties and polarization analysis provide evidence of a very complex volcanic structure. We conduct analyses to elucidate the macroscopic dynamic system associated with the explosions. The distribution of the times between successive explosion-quakes is exponential, implying a Poissonian process as observed at Stromboli volcano but on a different time scale. The sequence of the occurrence of the explosions can be described by classical intermittency. A coalescence Chandrasekar-Landau mean-field model reproduces gas bubble sizes comparable with those observed at the lava lake surface. Finally, the classical equation for the ascent of gas bubbles is generalized by adding a diffusive process. This model provides ascent velocities depending on the bubble radius: for gas bubbles greater than a few centimeters, variation in ascent velocity due to diffusion becomes negligible and the ascent velocity appears to be governed primarily by buoyancy.

Mots clés: Strombolian explosions; Erebus volcano; Diffusion

E. de Lauro, S. de Martino, M. Falanga, M. Palo. Modelling the macroscopic behavior of Strombolian explosions at Erebus volcano. Physics of the Earth and Planetary Interiors, 2009, 176 (3-4), pp.174. ⟨10.1016/j.pepi.2009.05.003⟩. ⟨hal-00573463⟩