 Incapillo is the source of the Incapillo ignimbrite , a medium @-@ sized deposit comparable to the Katmai ignimbrite . With a volume of about 20 @.@ 4 cubic kilometres ( 4 @.@ 9 cu mi ) , the Incapillo ignimbrite was erupted 0 @.@ 52 ± 0 @.@ 03 and 0 @.@ 51 ± 0 @.@ 04 million years ago . A caldera with dimensions of 5 by 6 kilometres ( 3 @.@ 1 mi × 3 @.@ 7 mi ) was formed during the eruption . Later volcanism generated more lava domes within the caldera and a debris flow in the Sierra de Veladero . The lake within the caldera may overlie an area of ongoing hydrothermal activity . 
