Volcanic ash fall hazard and risk

Title

Abstract

All explosive volcanic eruptions generate volcanic ash, fragments of rock that are produced when magma or vent material is explosively disintegrated. Volcanic ash is then convected upwards within the eruption column and carried downwind, falling out of suspension and potentially affecting communities across hundreds, or even thousands, of square kilometres. Ash is the most frequent, and often widespread, volcanic hazard and is produced by all explosive volcanic eruptions. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to potentially substantial societal impacts and costs, even at thicknesses of only a few millimetres. In this technical background paper, we discuss volcanic ash fall hazard modelling that has been implemented at the global and local (Neapolitan area, Italy) scales (Section 3). These models are probabilistic, i.e. they account for uncertainty in the input parameters to produce a large number of possible outcomes. Outputs are in the form of hazard maps and curves that show the probabilities associated with exceeding key hazard thresholds at given locations. As with any natural hazard, these results are subject to uncertainty and the local case study describes how ongoing research is working to better quantify this uncertainty through Bayesian methods and models. Further to the ash fall hazard assessments, we discuss the key components required to carry these hazard estimates forward to risk: namely identification of likely impacts and the response (vulnerability) of key sectors of society to ash fall impact.

Publication Date

Dec. 1, 2014, 12:58 p.m.

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Volcanic ash fall hazard and risk

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