Modelling the macroscopic behavior of Strombolian explosions at Erebus volcano

• Published in: Physics of the Earth and Planetary Interiors
• Main Authors: De Lauro, E., De Martino, S., Falanga, M., Palo, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: Strombolian explosions; Erebus volcano; Diffusion; Lava Lake; Antarc*; Antarctica
• Online Access: https://hal.archives-ouvertes.fr/hal-00573463; https://hal.archives-ouvertes.fr/hal-00573463/document; https://hal.archives-ouvertes.fr/hal-00573463/file/PEER_stage2_10.1016%252Fj.pepi.2009.05.003.pdf; https://doi.org/10.1016/j.pepi.2009.05.003

International audience 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.