Cerro Azul

The Cerro Azul stratovolcano is at the southern end of the Descabezado Grande-Cerro Azul eruptive system. It is a steep-sided edifice with a 500-m-wide summit crater open to the north. The three basaltic andesite "La Resoloma Craters" scoria vents are located below the W flank and the two "Los Hornitos" scoria cones on the lower SW flank. Quizapu, a major vent on the northern flank of Cerro Azul, formed in 1846 during the first historical eruption, accompanied by the emission of voluminous dacitic lava flows that traveled both east into the Estero Barroso valley and west into the Río Blanquillo valley. Quizapu was later the source of one of the world's largest explosive eruptions of the 20th century in 1932, which created a 600-700 m wide, 150-m-deep crater and ejected 9.5 km3 of dacitic tephra.