Self-sustained vibrations in volcanic areas extracted by Independent Component Analysis: a review and new results

• Published in: Nonlinear Processes in Geophysics
• Main Authors: DE LAURO E, DE MARTINO S, FALANGA M, PALO M
• Other Authors: DE LAURO, E, DE MARTINO, S, Falanga, M, Palo, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2011
• Subjects: earthquake; volcano; Independent Component Analysis; Neural Network; Unsupervised machine learning; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/11588/874194; https://doi.org/10.5194/npg-18-925-2011

We investigate the physical processes associated with volcanic tremor and explosions. A volcano is a complex system where a fluid source interacts with the solid edifice so generating seismic waves in a regime of low turbulence. Although the complex behavior escapes a simple universal description, the phases of activity generate stable (self-sustained) oscillations that can be described as a non-linear dynamical system of low dimensionality. So, the system requires to be investigated with non-linear methods able to individuate, decompose, and extract the main characteristics of the phenomenon. Independent Component Analysis (ICA), an entropy-based technique is a good candidate for this purpose. Here, we review the results of ICA applied to seismic signals acquired in some volcanic areas. We emphasize analogies and differences among the self-oscillations individuated in three cases: Stromboli (Italy), Erebus (Antarctica) and Volcán de Colima (Mexico). The waveforms of the extracted independent components are specific for each volcano, whereas the similarity can be ascribed to a very general common source mechanism involving the interaction between gas/magma flow and solid structures (the volcanic edifice). Indeed, chocking phenomena or inhomogeneities in the volcanic cavity can play the same role in generating self-oscillations as the languid and the reed do in musical instruments. The understanding of these background oscillations is relevant not only for explaining the volcanic source process and to make a forecast into the future, but sheds light on the physics of complex systems developing low turbulence.