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Instituto de Investigação
em Vulcanologia e Avaliação de Riscos
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Painéis ► em encontros internacionais


Referência Bibliográfica

ALATORRE-IBARGUENGOITIA, M.A., KUEPPERS, U., DELGADO-GRANADOS, H., DINGWELL, D.B. (2006) - Volcanic hazard assessment through analysis of physical characteristics and distribution of volcanic projectiles. AGU Fall Metting, San Francisco, USA, 11 - 15 de Dezembro (Poster).


Dealing with hazards at active volcanoes requires detailed knowledge of eruptive history and a good understanding of pre- and syn-eruptive processes. Despite improvement in monitoring systems, such an understanding cannot be based on direct field observations alone. Experimental and theoretical modelling are two essential components of modern volcanic hazard analysis. Volcanic ballistic projectiles (VBP) are a major hazard related to volcanic explosions. They may affect people, ecology, infrastructure and aircraft. In order to determine the potential areas for VBP fall, it is needed to estimate maximum ranges under different explosive scenarios. Each scenario is defined by the kinetic energy calculated from the impact location and its dimension and the physical characteristics of the projectiles (e.g. density, drag coefficient). The kinetic energy derives from the excess pressure in the expanding volatile phase driving the explosion. The design and development of "fragmentation bomb" technology has provided volcanology with the capability of controlled and systematic analysis of the fragmentation behavior of magma upon rapid decompression. Study of samples from several volcanoes has demonstrated a close relationship between open porosity and overpressure required for complete fragmentation of samples (fragmentation threshold). Analysis of the experimentally generated pyroclasts by fractal analysis shows that grain-size distribution is linearly dependent on open porosity and PEF (potential energy for fragmentation). Combination of these two approaches (kinetic energy from the distribution of VBP and potential energy (PEF) from scaled experiments and investigation of experimental and natural pyroclasts), taken together with seismic monitoring provides the potential for a significantly more refined hazard assessment of active, explosive volcanoes.