explosive volcanism volcanic eruption 12 Volcanoes 8 Argentina 6 Chile 6 Deposits 6 Hudson volcano 6 Southern Volcanic Zone 6 basalt 6 tephra 6 Aisen 4 Basalt 4 Mendoza 4 Mount Hudson 4 South America 4 Volcanic zone 4 chemical composition 4 island arc 4 phreatomagmatism 4 pumice 4 pyroclastic deposit 4 pyroclastic flow 4 volcanology 4 Aerial distribution 2 Alajuela 2 Alternating layers 2 Amphibole crystallization 2 Andean margin 2 Andean volcanism 2 Andes 2