San Pedro
"The composite volcano of San Pedro in the arid Atacama desert of northern Chile is one of the world's highest historically active volcanoes. The 6145-m-high basaltic andesite-to-dacitic San Pedro is located to the west of its older twin volcano, 6092-m-high San Pablo. The youngest cone of San Pedro was constructed within a large horseshoe-shaped escarpment left by the collapse of an older edifice, which produced a large debris avalanche to the west, perhaps accompanied by a major pumice eruption. Thick dacitic lava flows with steep-sided fronts mantle the upper portion of the younger cone. The youthful-looking La Poruña scoria cone on the western flank produced an 8-km-long lava flow, but Worner et al. (2000) obtained a surprisingly old Helium surface-exposure age of 103,000 years from a juvenile block of the lava flow. Reports of variable reliability mention historical eruptions of San Pedro in the 19th and 20th centuries."  -Smithsonian Volcano Archive
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