Largest explosive eruption in historical times in the Andes at Huaynaputina volcano, A.D. 1600, southern Peru

The largest explosive eruption (volcanic explosivity index of 6) in histori cal times in the Andes took place in A.D. 1600 at Huaynaputina volcano in s outhern Peru, According to chronicles, the eruption began on February 19 wi th a Plinian phase and lasted until March 6, Repeated tephra falls, pyrocla stic flows, and surges devastated an area 70 x 40 km(2) west of the vent an d affected all of southern Peru, and earthquakes shook the city of Arequipa 75 km away. Eight deposits, totaling 10.2-13.1 km(3) in bulk volume, are a ttributed to this eruption: (1) a widespread, similar to 8.1 km(3) pumice-f all deposit; (2) channeled ignimbrites (1.6-2 km(3)) with (3) ground-surge and ash-cloud-surge deposits; (4) widespread co-ignimbrite ash layers; (5) base-surge deposits; (6) unconfined ash-flow deposits; (7) crystal-rich dep osits; and (8) late ash-fall and surge deposits. Disruption of a hydrotherm al system and hydromagmatic interactions are thought to have fueled the lar ge-volume explosive eruption. Although the event triggered no caldera colla pse, ring fractures that cut the vent area point to the onset of a funnel-t ype caldera collapse.