Hazard zoning for volcanic ballistic impacts at El Chichón Volcano (Mexico)

The 1982 eruption of El Chichón Volcano in southeastern Mexico had a strong social, economic, and environmental impact. The eruption gave rise to the most disastrous volcanic events in Mexico, killing around 2000 inhabitants, displacing thousands, and resulting in severe economic losses. Despite some villages were relocated after this eruption, many people still live and work in the vicinities of the volcano and might be affected in the case of a new eruption. For this reason, it is important to identify the exposed zones. The published hazard map of El Chichón Volcano covers pyroclastic flows and surges, lahars, and ashfall, but not ballistic projectiles, which would represent an important threat in the case of an eruption. In fact, the fatalities reported in the first stage of the 1982 eruption were caused by ballistic projectiles and ashfall that induced roof collapse. In this study, the hazard zones for volcanic ballistic projectiles at El Chichón Volcano are delimited through a general methodology that has been applied to other volcanoes such as Popocatépetl (Alatorre-Ibarguengoitia et al. in Bull Volcanol 74:2155–2169, 2012. doi:10.1007/s00445-012-0657-2) and Colima (Alatorre-Ibarguengoitia et al. in Geol Soc Am Spec Paper 402:26–39, 2006). The maximum launching kinetic energy of projectiles identified in the field corresponding to past eruptions is reconstructed by using a ballistic model. These energies are then used to parameterize different explosion scenarios that can occur in the future. The maximum ranges expected for the projectiles in the different explosive scenarios defined for El Chichón Volcano are presented in a ballistic hazard map which complements the published hazard map. The responsible authorities may use this map to be able to mark off the restricted zones during volcanic crises.