Risk Assessment and Mitigation at Copahue Volcano

"Risk assessment" is a relatively new concept in Argentina, since the very first hazard map was only recently constructed on the basis of the 1992 eruption of Copahue volcano (Patagonia). Copahue is considered a very active volcanic system since 13 eruptive events have been recognized over the last 260 years. Most the events are phreatic and phreato-magmatic with VEI <= 2; nevertheless such eruptions represent a threat for the communities living in the surrounding areas of the emission centre, not only because of pyroclastic flows and tephra fall (the nearby villages, Caviahue and Copahue, have so far only experienced ash fallout), but also due to the possible formation of mud flows and flank collapse triggered by the volcanic activity. Owing to the frequent eruptions of Copahue, the most recent ones (2000, 2012) showed an increasing explosive character, hazard survey actions, such as thematic maps and contingency plans are constantly, though slowly, modified. The risk assessment described in this chapter calls for the implementation of the monitoring network in the Argentina side of the volcano, since the only currently active seismic stations (OVDAS) are located in the Chilean side of the volcanic edifice, Copahue volcano lying at the border between the two countries. Moreover, the Chilean observatory adopts criteria of alert levels, whichare distinctly different with respect to those of Argentina Civil Defense, producing misleading information to the population. The villages of Copahue and Caviahue are regarded as extremely vulnerable to possible future eruptions if larger magnitude events should occur. A review of the presently available potential hazard map, an improvement of people's education about the volcanic risks and a more interactive cooperation between the Chilean and Argentina scientific and administrative institutions are some of the immediate countermeasures to be taken into account before a new explosive phase at Copahue.