Satellite analysis and PUFF simulation of the eruptive cloud generated by the Mount Etna paroxysm of 22 July 1998

We applied the PUFF algorithm [Searcy et al., 1998] to simulate the space-time evolution of the eruptive cloud generated by one of the main paroxysms to have occurred this past century at Etna volcano, namely the 22 July 1998 explosive event at the Voragine summit crater. The comparison of PUFF simulations to satellite images of the ash cloud at different times allowed us to estimate several parameters of the eruptive event, such as onset time, duration, ash cloud height and shape, and pyroclast size. Based on this analysis, we concluded that the paroxysm started around 1645 GMT, lasted between 20 and 40 min, and generated a Poissonian-shaped ash column nearly 13 km high and composed of particles with a mean diameter (MD) of 10(-3) m and size logarithmic standard deviation (LSD) equal to 1.5. The PUFF simulations using horizontal and vertical diffusivity values of 5000 and 10 m(2) s(-1), respectively, provided the best agreement to the eruption clouds observed on satellite images. The results were compared to the information available in the literature concerning the eruption, e. g., volcanological, video camera, and volcanic tremor data. The analysis showed that the method of simulating the eruptive clouds and comparing simulations to satellite images can give a contribution to the study of paroxysmal events generated by the Etna volcano. Also, the degree of accuracy of the cloud simulation leads us to be optimistic about the potential of using this method as a tool for hazard mitigation in the Etna region, with particular applications to air traffic.