Volcano hazards and risks in Chile

Abstract Active volcanoes in Chile occur along the Andean cordillera with interruption defined by the Pampean flat subduction segment and the shorter Patagonian gap. They belong to the Central, Southern, and Austral volcanic provinces of the Andes. A total of c.90 active volcanoes are officially considered by the government agencies, although only 23 satisfy a stricter criterion of at least one eruption since AD 1900 and 15 would be semiactive (with historical post-AD 1500 eruptions with or without unrest recorded since AD 1900); the others being semidormant or fully-dormant. There are striking geochemical and eruptive differences from the three volcanic provinces. Compositions of the erupted magmas are more evolved in CVZ and basalts dominates in SVZ, where also the highest VEI eruptions occurred and the most voluminous stratovolcanoes are present. Related hazards are also contrasting and different scoring schemes show higher hazard values for the SVZ. Exposure and social vulnerability show in turn a more complex pattern being exposed higher in SVZ (the most populated segment where also critical infrastructure is present). Social vulnerability is higher in some areas of the CVZ and specific cases in SVZ. The latter (Copahue Volcano surroundings) becomes a hotspot for the impact of volcanic eruption because of concurrent high hazard, exposure, and social vulnerability. Monitoring capacity has been evolving positively since the eruption of Chaiten Volcano in 2008, although some improvements are warranted for very high and high threat volcanoes where multiparametric observations with the denser network would help to better forecast impending eruptions.