Using an existing technique for mapping the hazard zones of volcano-induced lahars (mudfl ows), volcanologists from Penn State University analysed data from a number of recent explosive eruptions, including Indonesia’s Mount Merapi, the Soufrière Hills volcano on the British territory of Montserrat, Mount Unzen in Japan, and Colima in Mexico.

By studying the behaviour of pyroclastic fl ows in these instances – taking into account the cross-sectional areas of the flows, the area covered and the amount of material in the flow – they were able to develop a predictive equation. This was then combined with GIS maps to show the predicted path and risk zones of a pyroclastic flow on a given volcano.

‘The approach worked for water-saturated mud flows – we thought that maybe it would work for pyroclastic fl ows,’ said Barry Voight, professor emeritus of geosciences at Penn State University. ‘Such maps, along with other pertinent information, such as risk information, event probabilities and so on, can then be considered by hazard and risk specialists or other decision-makers, who can render judgments on whether zoning and/or evacuation is necessary for the public welfare. These maps can be created quickly, in a few days, and emailed anywhere in the world. We can now avoid doing “too little, too late” in our mitigation response.’

April 2009